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Andersen ML, Pires GN, Tufik S. The Impact of Sleep: From Ancient Rituals to Modern Challenges. Sleep Sci 2024; 17:e203-e207. [PMID: 38846589 PMCID: PMC11152632 DOI: 10.1055/s-0043-1777785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 08/14/2023] [Indexed: 06/09/2024] Open
Abstract
Although sleep is crucial for mental and physical health, insufficient sleep is a growing problem in our modern society. In general, adults need approximately eight hours of sleep per night, but this is often unfeasible nowadays. This sleep restriction has been observed, and it has worsened, throughout the past two centuries; therefore, it is more attributed to socioeconomic changes than to biological adaptations. The most important factors to contribute to this sleep restriction were the popularization of artificial light and industrialization. The present manuscript briefly overviews, from a socioanthropological perspective, the reasons why sleep has been impacted, disclosing its effects on individuals and on society.
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Affiliation(s)
- Monica L. Andersen
- Departamento de Psicobiologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
- Sleep Institute, Associação Fundo Incentivo à Pesquisa (AFIP), São Paulo, SP, Brazil
| | - Gabriel Natan Pires
- Departamento de Psicobiologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
- Sleep Institute, Associação Fundo Incentivo à Pesquisa (AFIP), São Paulo, SP, Brazil
| | - Sergio Tufik
- Departamento de Psicobiologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
- Sleep Institute, Associação Fundo Incentivo à Pesquisa (AFIP), São Paulo, SP, Brazil
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2
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Tassino B, Silva A. Environmental, social, and behavioral challenges of the human circadian clock in real-life conditions. Front Physiol 2024; 15:1347377. [PMID: 38516211 PMCID: PMC10954801 DOI: 10.3389/fphys.2024.1347377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/26/2024] [Indexed: 03/23/2024] Open
Abstract
Urban environments, in which ambient light has become a less-reliable entrainer, are challenging for the biological clock to maintain performance. As a consequence, human circadian rhythms are less robust and more variable among individuals. Assessing the individual phase of entrainment, as well as its plastic shifts in response to disturbances of the physical and social environment, is a way to measure circadian disruption. However, this is still difficult to address in real-life scenarios in which several factors modulate the circadian phase not always in a concerted manner. In this perspective, we present the contribution of two real-life situations, in which the circadian system is challenged by important alterations in entraining signals: 1) a trip to the Antarctic summer (socio-environmental challenge), and 2) dancers trained in morning/night shifts (socio-behavioral challenge). Both natural chronobiological experiments are helpful in exploring the functioning and plasticity of the circadian clock and allow for considering individual characteristics and history.
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Affiliation(s)
- Bettina Tassino
- Sección Etología, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
- Grupo de Investigación en Cronobiología, Universidad de la República, Montevideo, Uruguay
| | - Ana Silva
- Grupo de Investigación en Cronobiología, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Neurociencias, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
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3
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Fjell AM, Walhovd KB. Individual sleep need is flexible and dynamically related to cognitive function. Nat Hum Behav 2024; 8:422-430. [PMID: 38379065 DOI: 10.1038/s41562-024-01827-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 01/15/2024] [Indexed: 02/22/2024]
Abstract
Given that sleep deprivation studies consistently show that short sleep causes neurocognitive deficits, the effects of insufficient sleep on brain health and cognition are of great interest and concern. Here we argue that experimentally restricted sleep is not a good model for understanding the normal functions of sleep in naturalistic settings. Cross-disciplinary research suggests that human sleep is remarkably dependent on environmental conditions and social norms, thus escaping universally applicable rules. Sleep need varies over time and differs between individuals, showing a complex relationship with neurocognitive function. This aspect of sleep is rarely addressed in experimental work and is not reflected in expert recommendations about sleep duration. We recommend focusing on the role of individual and environmental factors to improve our understanding of the relationship between human sleep and cognition.
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Affiliation(s)
- Anders M Fjell
- Center for Lifespan Changes in Brain and Cognition, University of Oslo, Oslo, Norway.
- Center for Computational Radiology and Artificial Intelligence, Oslo University Hospital, Oslo, Norway.
| | - Kristine B Walhovd
- Center for Lifespan Changes in Brain and Cognition, University of Oslo, Oslo, Norway
- Center for Computational Radiology and Artificial Intelligence, Oslo University Hospital, Oslo, Norway
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4
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Louzada FM, Cesar-Silva AHA, Moreno CRC, Azevedo CVM, Casiraghi LP, de la Iglesia HO. Late evening electric light exposure is associated with low sleep regularity in adolescents living in rural areas. Sleep Health 2024; 10:S180-S183. [PMID: 37783576 DOI: 10.1016/j.sleh.2023.08.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 08/19/2023] [Accepted: 08/22/2023] [Indexed: 10/04/2023]
Abstract
In this study, we tested the prediction that sleep regularity would be lower in adolescents exposed to late evening electric light (LEEL) than in those without exposure to it. The Sleep Regularity Index was calculated based on actigraph recordings from adolescents living in rural communities in Argentina and Brazil that were either exposed to LEEL or not. The effect of the LEEL on sleep variables was tested using linear models considering sex and age, as well as accounting for the differences between countries. Sleep onset was delayed, sleep duration shortened, and Sleep Regularity Index was 4 [1-8] points lower in the group exposed to LEEL (p = .0176, eta2 =0.13). Our results show that beyond sleep phase and duration, which are known to be affected by LEEL in this age group, sleep irregularity should also be considered as an important outcome variable when assessing the adverse effects of evening light on adolescents.
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Affiliation(s)
| | | | - Claudia R C Moreno
- Department of Health, Life Cycles and Society, School of Public Health, University of São Paulo, São Paulo, Brazil
| | - Carolina V M Azevedo
- Department of Physiology and Behavior, Federal University of Rio Grande do Norte, Natal, Brazil
| | - Leandro P Casiraghi
- Department of Biology, University of Washington, Seattle, Washington, USA; Laboratorio Interdisciplinario del Tiempo (LITERA), Escuela de Educación, Universidad de San Andrés, Victoria, Argentina/CONICET
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5
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Cox RC, Blumenstein AB, Burke TM, Depner CM, Guerin MK, Hay-Arthur E, Higgins J, Knauer OA, Lanza SM, Markwald RR, Melanson EL, McHill AW, Morton SJ, Ritchie HK, Smith MR, Smits AN, Sprecher KE, Stothard ER, Withrow D, Wright KP. Distribution of dim light melatonin offset (DLMOff) and phase relationship to waketime in healthy adults and associations with chronotype. Sleep Health 2024; 10:S76-S83. [PMID: 37777359 DOI: 10.1016/j.sleh.2023.08.017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 10/02/2023]
Abstract
OBJECTIVES Dim light melatonin onset, or the rise in melatonin levels representing the beginning of the biological night, is the gold standard indicator of circadian phase. Considerably less is known about dim light melatonin offset, or the decrease in melatonin to low daytime levels representing the end of the biological night. In the context of insufficient sleep, morning circadian misalignment, or energy intake after waketime but before dim light melatonin offset, is linked to impaired insulin sensitivity, suggesting the need to characterize dim light melatonin offset and identify risk for morning circadian misalignment. METHODS We examined the distributions of dim light melatonin offset clock hour and the phase relationship between dim light melatonin offset and waketime, and associations between dim light melatonin offset, phase relationship, and chronotype in healthy adults (N = 62) who completed baseline protocols measuring components of the circadian melatonin rhythm and chronotype. RESULTS 74.4% demonstrated dim light melatonin offset after waketime, indicating most healthy adults wake up before the end of biological night. Later chronotype (morningness-eveningness, mid-sleep on free days corrected, and average mid-sleep) was associated with later dim light melatonin offset clock hour. Later chronotype was also associated with a larger, positive phase relationship between dim light melatonin offset and waketime, except for morningness-eveningness. CONCLUSIONS These findings suggest morning circadian misalignment risk among healthy adults, which would not be detected if only dim light melatonin onset were assessed. Chronotype measured by sleep timing may better predict this risk in healthy adults keeping a consistent sleep schedule than morningness-eveningness preferences. Additional research is needed to develop circadian biomarkers to predict dim light melatonin offset and evaluate appropriate dim light melatonin offset timing to promote health.
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Affiliation(s)
- Rebecca C Cox
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Alivia B Blumenstein
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Tina M Burke
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Christopher M Depner
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Department of Health and Kinesiology, University of Utah, Salt Lake City, Utah, USA
| | - Molly K Guerin
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Emily Hay-Arthur
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Janine Higgins
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Oliver A Knauer
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Shannon M Lanza
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Rachel R Markwald
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Naval Health Research Center, San Diego, California, USA
| | - Edward L Melanson
- Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA; Division of Geriatric Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Andrew W McHill
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon, USA
| | - Sarah J Morton
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Hannah K Ritchie
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Mark R Smith
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Alexandra N Smits
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Kate E Sprecher
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Ellen R Stothard
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Colorado Sleep Institute, Boulder, Colorado, USA
| | - Dana Withrow
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Kenneth P Wright
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA; Division of Endocrinology, Metabolism, and Diabetes, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
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6
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de Sousa CAR, Nogueira LF, Cipolla-Neto J, Moreno CRDC, Marqueze EC. 12-week melatonin administration had no effect on diabetes risk markers and fat intake in overweight women night workers. Front Nutr 2024; 11:1285398. [PMID: 38318471 PMCID: PMC10839037 DOI: 10.3389/fnut.2024.1285398] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 01/04/2024] [Indexed: 02/07/2024] Open
Abstract
Introduction Interactions between circadian clocks and key mediators of chronic low-grade inflammation associated with fat consumption may be important in maintaining metabolic homeostasis and may pose a risk for the development of obesity-associated comorbidities, especially type 2 diabetes (T2DM). Objective The aims of the present study were to evaluate the effects of melatonin administration on diabetes risk markers according to dietary lipid profile (pro-inflammatory versus anti-inflammatory) in excessive weight night workers, and to determine the effect of administration on fat consumption profile. Methods A randomized, controlled, double-blind, crossover clinical trial involving 27 nursing professionals working permanent night shifts under a 12×36-hour system. The melatonin group (12 weeks) used synthetic melatonin (3 mg) only on days off and between shifts, while the placebo group (12 weeks) was instructed to take a placebo, also on days off and between shifts. For inflammatory characteristics, participants were divided into pro-inflammatory (saturated fats, trans fats and cholesterol) and anti-inflammatory (monounsaturated, polyunsaturated fats and EPA + DHA) groups according to fatty acid determinations. At baseline and at the end of each phase, blood glucose, insulin, glycosylated hemoglobin plasma concentrations were collected, and HOMA-IR was calculated. Conclusion Melatonin administration for 12 weeks had no effect on T2DM risk markers according to dietary lipid profile (pro-inflammatory or anti-inflammatory potential) in excessive weight night workers. Among the limitations of the study include the fact that the low dose may have influenced the results expected in the hypothesis, and individual adaptations to night work were not evaluated. The insights discussed are important for future research investigating the influence of melatonin and fats considered anti- or pro-inflammatory on glucose and insulin homeostasis related to night work.
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Affiliation(s)
- Carlos Alberto Rodrigues de Sousa
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Department of Epidemiology, Postgraduate Program in Public Health, Catholic University of Santos, São Paulo, Brazil
| | - Luciana Fidalgo Nogueira
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - José Cipolla-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Claudia Roberta de Castro Moreno
- Department of Epidemiology, Postgraduate Program in Public Health, Catholic University of Santos, São Paulo, Brazil
- Department of Health, Life Cycles and Society, Faculty of Public Health, University of São Paulo, São Paulo, Brazil
| | - Elaine Cristina Marqueze
- Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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7
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Silva-Caballero A, Ball HL, Kramer KL, Bentley GR. Sleep tight! Adolescent sleep quality across three distinct sleep ecologies. Evol Med Public Health 2023; 11:448-460. [PMID: 38044930 PMCID: PMC10693291 DOI: 10.1093/emph/eoad040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/05/2023] [Indexed: 12/05/2023] Open
Abstract
Background and objectives Good sleep quality, associated with few arousals, no daytime sleepiness and self-satisfaction with one's sleep, is pivotal for adolescent growth, maturation, cognition and overall health. This article aims to identify what ecological factors impact adolescent sleep quality across three distinct sleep ecologies representing a gradient of dense urbanity to small, rural environments with scarce artificial lighting and no Internet. Methodology We analyze variation of sleep efficiency, a quantitative measure of sleep quality-defined as the ratio of total time spent asleep to total time dedicated to sleep-in two agricultural indigenous populations and one post-industrial group in Mexico (Campeche = 44, Puebla = 51, Mexico City = 50, respectively). Data collection included actigraphy, sleep diaries, questionnaires, interviews and ethnographic observations. We fit linear models to examine sleep efficiency variation within and between groups. Results We found that sleep efficiency varied significantly across sites, being highest in Mexico City (88%) and lowest in Campeche (75%). We found that variation in sleep efficiency was significantly associated with nightly exposure to light and social sleep practices. Conclusions and implications Our findings point toward contextual cost-benefits of sleep disruption in adolescence. We highlight the need to prioritize research on adolescent sleep quality across distinct developmental ecologies and its impact on health to improve adolescent wellbeing through evidence-based health practices.
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Affiliation(s)
- Andrea Silva-Caballero
- Institute of Anthropological Research, National Autonomous University of Mexico, Mexico City, 04510, Mexico
- Department of Anthropology, Durham University, Durham, DH1 3LE, UK
| | - Helen L Ball
- Department of Anthropology, Durham University, Durham, DH1 3LE, UK
| | - Karen L Kramer
- Department of Anthropology, Univesity of Utah, Salt Lake City, RM 4625, USA
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Castillo J, Tonon AC, Hidalgo MP, Silva A, Tassino B. Individual light history matters to deal with the Antarctic summer. Sci Rep 2023; 13:12081. [PMID: 37495664 PMCID: PMC10372057 DOI: 10.1038/s41598-023-39315-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Accepted: 07/23/2023] [Indexed: 07/28/2023] Open
Abstract
The effect of light, main zeitgeber of the circadian system, depends on the time of day it is received. A brief trip to the Antarctic summer (ANT) allowed us to explore the impact of a sudden and synchronized increase in light exposure on activity-rest rhythms and sleep patterns of 11 Uruguayan university students, and to assess the significance of light history in determining individual circadian phase shift. Measurements collected in the peri-equinox in Montevideo, Uruguay (baseline situation, MVD) and in ANT, included sleep logs, actigraphy, and salivary melatonin to determine dim-light melatonin onset (DLMO), the most reliable marker of circadian phase. The increase in light exposure in ANT with respect to MVD (affecting both light-sensitive windows with opposite effects on the circadian phase) resulted in no net change in DLMO among participants as some participants advanced their DLMO and some others delayed it. The ultimate cause of each participant's distinctive circadian phase shift relied on the unique change in light exposure each individual was subjected to between their MVD and ANT. This study shows an association between the individual light history and the circadian phase shift.
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Affiliation(s)
- Julieta Castillo
- Grupo Cronobiología, Comisión Sectorial de Investigación Científica, Universidad de la República, Montevideo, Uruguay
| | - André C Tonon
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - María Paz Hidalgo
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Ana Silva
- Grupo Cronobiología, Comisión Sectorial de Investigación Científica, Universidad de la República, Montevideo, Uruguay
- Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Bettina Tassino
- Grupo Cronobiología, Comisión Sectorial de Investigación Científica, Universidad de la República, Montevideo, Uruguay.
- Sección Etología, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400, Montevideo, Uruguay.
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9
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Eto T, Higuchi S. Review on age-related differences in non-visual effects of light: melatonin suppression, circadian phase shift and pupillary light reflex in children to older adults. J Physiol Anthropol 2023; 42:11. [PMID: 37355647 DOI: 10.1186/s40101-023-00328-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 06/15/2023] [Indexed: 06/26/2023] Open
Abstract
Physiological effects of light exposure in humans are diverse. Among them, the circadian rhythm phase shift effect in order to maintain a 24-h cycle of the biological clock is referred to as non-visual effects of light collectively with melatonin suppression and pupillary light reflex. The non-visual effects of light may differ depending on age, and clarifying age-related differences in the non-visual effects of light is important for providing appropriate light environments for people of different ages. Therefore, in various research fields, including physiological anthropology, many studies on the effects of age on non-visual functions have been carried out in older people, children and adolescents by comparing the effects with young adults. However, whether the non-visual effects of light vary depending on age and, if so, what factors contribute to the differences have remained unclear. In this review, results of past and recent studies on age-related differences in the non-visual effects of light are presented and discussed in order to provide clues for answering the question of whether non-visual effects of light actually vary depending on age. Some studies, especially studies focusing on older people, have shown age-related differences in non-visual functions including differences in melatonin suppression, circadian phase shift and pupillary light reflex, while other studies have shown no differences. Studies showing age-related differences in the non-visual effects of light have suspected senile constriction and crystalline lens opacity as factors contributing to the differences, while studies showing no age-related differences have suspected the presence of a compensatory mechanism. Some studies in children and adolescents have shown that children's non-visual functions may be highly sensitive to light, but the studies comparing with other age groups seem to have been limited. In order to study age-related differences in non-visual effects in detail, comparative studies should be conducted using subjects having a wide range of ages and with as much control as possible for intensity, wavelength component, duration, circadian timing, illumination method of light exposure, and other factors (mydriasis or non-mydriasis, cataracts or not in the older adults, etc.).
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Affiliation(s)
- Taisuke Eto
- Research Fellow of the Japan Society for the Promotion of Science, Kodaira, Japan
- Department of Sleep-Wake Disorders, National Center of Neurology and Psychiatry, National Institute of Mental Health, Kodaira, Japan
| | - Shigekazu Higuchi
- Department of Human Life Design and Science, Faculty of Design, Kyushu University, Fukuoka, Japan.
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Costa R, Mangini C, Domenie ED, Zarantonello L, Montagnese S. Circadian rhythms and the liver. Liver Int 2023; 43:534-545. [PMID: 36577705 DOI: 10.1111/liv.15501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/29/2022] [Accepted: 12/15/2022] [Indexed: 12/30/2022]
Abstract
This narrative review briefly describes the mammalian circadian timing system, the specific features of the liver clock, also by comparison with other peripheral clocks, the role of the liver clock in the preparation of food intake, and its relationship with energy metabolism. It then goes on to provide a chronobiological perspective of the pathophysiology and management of several types of liver disease, with a particular focus on metabolic-associated fatty liver disease (MAFLD), decompensated cirrhosis and liver transplantation. Finally, it provides some insight into the potential contribution of circadian principles and circadian hygiene practices in preventing MAFLD, improving the prognosis of advanced liver disease and modulating liver transplantation outcomes.
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Affiliation(s)
- Rodolfo Costa
- Institute of Neuroscience, National Research Council (CNR), Padova, Italy.,Department of Biology, University of Padova, Padova, Italy.,Chronobiology Section, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Chiara Mangini
- Department of Medicine, University of Padova, Padova, Italy
| | | | | | - Sara Montagnese
- Chronobiology Section, Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK.,Department of Medicine, University of Padova, Padova, Italy
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11
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Dunster GP, Hua I, Grahe A, Fleischer JG, Panda S, Wright KP, Vetter C, Doherty JH, de la Iglesia HO. Daytime light exposure is a strong predictor of seasonal variation in sleep and circadian timing of university students. J Pineal Res 2023; 74:e12843. [PMID: 36404490 DOI: 10.1111/jpi.12843] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/11/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022]
Abstract
In the absence of electric light, sleep for humans typically starts soon after dusk and at higher latitudes daily sleep timing changes seasonally as photoperiod changes. However, access to electric light shields humans from natural photoperiod changes, and whether seasonal changes in sleep occur despite this isolation from the natural light-dark cycle remains a matter of controversy. We measured sleep timing in over 500 university students living in the city of Seattle, WA (47.6°N) throughout the four seasons; we show that even when students are following a school schedule, sleep timing is delayed during the fall and winter. For instance, during the winter school days, students fell asleep 35 min later and woke up 27 min later (under daylight-savings time) than students during the summer school days, a change that is an hour larger relative to solar midnight. Furthermore, chronotype defined by mid-sleep on free days corrected for oversleep (MSFc), an indirect estimate of circadian phase, was more than 30 min later in the winter compared with the summer. Analysis of the effect of light exposure showed that the number of hours of light exposure to at least 50 lux during the daytime was a stronger predictor of MSFc than the exposure time to this illuminance after dusk. Specifically, MSFc was advanced by 30 min for each additional hour of light exposure during daytime and delayed by only 15 min for each additional hour of postdusk exposure to light. Additionally, the time of the day of exposure to high light intensities was more predictive of MSFc when daytime exposure was considered than when exposure for the full 24-h day was considered. Our results show that although sleep time is highly synchronized to social time, a delayed timing of sleep is evident during the winter months. They also suggest that daily exposure to daylight is key to prevent this delayed phase of the circadian clock and thus circadian disruption that is typically exacerbated in high-latitude winters.
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Affiliation(s)
- Gideon P Dunster
- Department of Biology, University of Washington, Seattle, Washington, USA
| | - Isabelle Hua
- Department of Biology, University of Washington, Seattle, Washington, USA
| | - Alex Grahe
- Department of Biology, University of Washington, Seattle, Washington, USA
| | - Jason G Fleischer
- Regulatory Biology Laboratory, Salk Institute, La Jolla, California, USA
| | | | - Kenneth P Wright
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Céline Vetter
- Circadian and Sleep Epidemiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Jennifer H Doherty
- Department of Biology, University of Washington, Seattle, Washington, USA
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12
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Sleep deprivation among adolescents in urban and indigenous-rural Mexican communities. Sci Rep 2023; 13:1058. [PMID: 36658329 PMCID: PMC9852252 DOI: 10.1038/s41598-023-28330-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 01/17/2023] [Indexed: 01/20/2023] Open
Abstract
Comparing the nature of adolescent sleep across urban and more isolated, rural settings through an ecological, cross-cultural perspective represents one way to inform sleep nuances and broaden our understanding of human development, wellbeing and evolution. Here we tested the Social Jetlag Hypothesis, according to which contemporary, urban lifestyles and technological advances are associated with sleep insufficiency in adolescents. We documented the adolescent sleep duration (11-16 years old; X̅ = 13.7 ± 1.21; n = 145) in two small agricultural, indigenous and one densely urban context in Mexico to investigate whether adolescents in socio-ecologically distinct locations experience sleep deprivation. Sleep data was assembled with actigraphy, sleep diaries and standardized questionnaires. We employed multilevel models to analyze how distinct biological and socio-cultural factors (i.e., pubertal maturation, chronotype, napping, gender, working/schooling, access to screen-based devices, exposure to light, and social sleep practices) shape adolescent sleep duration. Results suggest that the prevalence of adolescent short sleep quotas is similar in rural, more traditional environments compared to highly urbanized societies, and highlight the influence of social activities on the expression of human sleep. This study challenges current assumptions about natural sleep and how adolescents slept before contemporary technological changes occurred.
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Eto T, Kitamura S, Nishimura K, Takeoka K, Nishimura Y, Lee SI, Ohashi M, Shikano A, Noi S, Higuchi S. Circadian phase advances in children during camping life according to the natural light-dark cycle. J Physiol Anthropol 2022; 41:42. [PMID: 36527162 PMCID: PMC9756595 DOI: 10.1186/s40101-022-00316-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND It is known that the circadian rhythm phase in adults can be advanced in a natural light-dark cycle without electrical lighting. However, the effect of advanced sleep-wake timing according to the natural light-dark cycle on children's circadian phase is unclear. We investigated the effects of approximately 2 weeks of camping life with little access to artificial lighting on children's circadian phases. We also conducted an exploratory examination on the effects of wake time according to natural sunrise time on the manner of the advance of their circadian phases. METHODS Twenty-one healthy children (mean ± SD age, 10.6 ± 1.4 years) participated in a camping program with wake time (4:00) being earlier than sunrise time (EW condition), and 21 healthy children (10.4 ± 1.1 years) participated in a camping program with wake time (5:00) being almost matched to sunrise time (SW condition). Salivary dim light melatonin onset (DLMO) before the camping program and that after approximately 2 weeks of camping were compared. RESULTS DLMO was advanced by approximately 2 h after the camping program compared with the circadian phase in daily life in both conditions. In addition, the advances in DLMO were significantly correlated with mid-sleep points before the camp in both conditions (EW: r = 0.72, p < 0.01, SW: r = 0.70, p < 0.01). These correlations mean that the phase advance was greater for the children with delayed sleep habits in daily life. Furthermore, in the EW condition, mean DLMO after the camp (18:09 ± 0:33 h) was earlier than natural sunset time and there was no significant decrease in interindividual variability in DLMO. On the other hand, in the SW condition, mean DLMO after the camp (18:43 ± 0:20 h) matched natural sunset time and interindividual variability in DLMO was significantly lower than that before the camp. CONCLUSIONS Camping with advanced sleep and wake timing under natural sunlight advances children's circadian phases. However, DLMO earlier than sunset in an early waking condition may lead to large interindividual variability in the circadian rhythm phase.
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Affiliation(s)
- Taisuke Eto
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,Research Fellow of the Japan Society for the Promotion of Science, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.416859.70000 0000 9832 2227Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8553 Japan
| | - Shingo Kitamura
- grid.416859.70000 0000 9832 2227Department of Sleep-Wake Disorders, National Institute of Mental Health, National Center of Neurology and Psychiatry, 4-1-1 Ogawa-Higashi, Kodaira, Tokyo, 187-8553 Japan
| | - Kana Nishimura
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Kota Takeoka
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Yuki Nishimura
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.415747.4Occupational Stress and Health Management Research Group, National Institute of Occupational Safety and Health, 6-21-1 Nagao, Tama-ku, Kawasaki, Kanagawa 214-8585 Japan
| | - Sang-il Lee
- grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,grid.39158.360000 0001 2173 7691Laboratory of Environmental Ergonomics, Faculty of Engineering, Hokkaido University, Kita 13, Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628 Japan
| | - Michihiro Ohashi
- grid.177174.30000 0001 2242 4849Graduate School of Integrated Frontier Sciences, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan ,Research Fellow of the Japan Society for the Promotion of Science, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
| | - Akiko Shikano
- grid.412200.50000 0001 2228 003XFaculty of Sport Science, Nippon Sport Science University, 7-1-1 Fukasawa, Setagaya-ku, Tokyo, 158-8508 Japan
| | - Shingo Noi
- grid.412200.50000 0001 2228 003XFaculty of Sport Science, Nippon Sport Science University, 7-1-1 Fukasawa, Setagaya-ku, Tokyo, 158-8508 Japan
| | - Shigekazu Higuchi
- grid.177174.30000 0001 2242 4849Department of Human Science, Faculty of Design, Kyushu University, 4-9-1 Shiobaru, Minami-ku, Fukuoka, 815-8540 Japan
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McKinnon L, Shattuck EC, Samson DR. Sound reasons for unsound sleep: Comparative support for the sentinel hypothesis in industrial and nonindustrial groups. Evol Med Public Health 2022; 11:53-66. [PMID: 36945298 PMCID: PMC10024786 DOI: 10.1093/emph/eoac039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Indexed: 11/23/2022] Open
Abstract
Background and objectives Sleep is a vulnerable state in which individuals are more susceptible to threat, which may have led to evolved mechanisms for increasing safety. The sentinel hypothesis proposes that brief awakenings during sleep may be a strategy for detecting and responding to environmental threats. Observations of sleep segmentation and group sentinelization in hunter-gatherer and small-scale communities support this hypothesis, but to date it has not been tested in comparisons with industrial populations characterized by more secure sleep environments. Methodology Here, we compare wake after sleep onset (WASO), a quantitative measure of nighttime awakenings, between two nonindustrial and two industrial populations: Hadza hunter-gatherers (n = 33), Malagasy small-scale agriculturalists (n = 38), and Hispanic (n = 1,531) and non-Hispanic White (NHW) (n = 347) Americans. We compared nighttime awakenings between these groups using actigraphically-measured sleep data. We fit linear models to assess whether WASO varies across groups, controlling for sex and age. Results We found that WASO varies significantly by group membership and is highest in Hadza (2.44 h) and Malagasy (1.93 h) and lowest in non-Hispanic Whites (0.69 h). Hispanics demonstrate intermediate WASO (0.86 h), which is significantly more than NHW participants. After performing supplementary analysis within the Hispanic sample, we found that WASO is significantly and positively associated with increased perception of neighborhood violence. Conclusions and implications Consistent with principles central to evolutionary medicine, we propose that evolved mechanisms to increase vigilance during sleep may now be mismatched with relatively safer environments, and in part responsible for driving poor sleep health.
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Affiliation(s)
- Leela McKinnon
- Department of Anthropology, University of Toronto Mississauga, Mississauga, ON, CanadaL5L 1C6
| | - Eric C Shattuck
- Department of Anthropology, University of Toronto Mississauga, Mississauga, ON, CanadaL5L 1C6
- Institute for Health Disparities Research, University of Texas at San Antonio, San Antonio, TX 78249, USA
- Department of Public Health, University of Texas at San Antonio, San Antonio, TX 78249, USA
| | - David R Samson
- Department of Anthropology, University of Toronto Mississauga, Mississauga, ON, CanadaL5L 1C6
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McKinnon L, Samson DR, Nunn CL, Rowlands A, Salvante KG, Nepomnaschy PA. Technological infrastructure, sleep, and rest-activity patterns in a Kaqchikel Maya community. PLoS One 2022; 17:e0277416. [PMID: 36383619 PMCID: PMC9668134 DOI: 10.1371/journal.pone.0277416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 10/26/2022] [Indexed: 11/17/2022] Open
Abstract
Sleep duration, quality, and rest-activity pattern-a measure for inferring circadian rhythm-are influenced by multiple factors including access to electricity. Recent findings suggest that the safety and comfort afforded by technology may improve sleep but negatively impact rest-activity stability. According to the circadian entrainment hypothesis, increased access to electric lighting should lead to weaker and less uniform circadian rhythms, measured by stability of rest-activity patterns. Here, we investigate sleep in a Maya community in Guatemala who are in a transitional stage of industrialization. We predicted that (i) sleep will be shorter and less efficient in this population than in industrial settings, and that (ii) rest-activity patterns will be weaker and less stable than in contexts with greater exposure to the natural environment and stronger and more stable than in settings more buffered by technologic infrastructure. Our results were mixed. Compared to more industrialized settings, in our study population sleep was 4.87% less efficient (78.39% vs 83.26%). We found no significant difference in sleep duration. Rest-activity patterns were more uniform and less variable than in industrial settings (interdaily stability = 0.58 vs 0.43; intradaily variability = 0.53 vs 0.60). Our results suggest that industrialization does not inherently reduce characteristics of sleep quality; instead, the safety and comfort afforded by technological development may improve sleep, and an intermediate degree of environmental exposure and technological buffering may support circadian rhythm strength and stability.
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Affiliation(s)
- Leela McKinnon
- Department of Anthropology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - David R. Samson
- Department of Anthropology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Charles L. Nunn
- Department of Evolutionary Anthropology, Duke University, Durham, NC, United States of America
- Duke Global Health Institute, Duke University, Durham, NC, United States of America
| | - Amanda Rowlands
- Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Katrina G. Salvante
- Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Pablo A. Nepomnaschy
- Maternal and Child Health Laboratory, Faculty of Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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16
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Benedetti M, Maierová L, Cajochen C, Scartezzini JL, Münch M. Optimized office lighting advances melatonin phase and peripheral heat loss prior bedtime. Sci Rep 2022; 12:4267. [PMID: 35277539 PMCID: PMC8917232 DOI: 10.1038/s41598-022-07522-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 02/16/2022] [Indexed: 12/05/2022] Open
Abstract
Improving indoor lighting conditions at the workplace has the potential to support proper circadian entrainment of hormonal rhythms, sleep, and well-being. We tested the effects of optimized dynamic daylight and electric lighting on circadian phase of melatonin, cortisol and skin temperatures in office workers. We equipped one office room with an automated controller for blinds and electric lighting, optimized for dynamic lighting (= Test room), and a second room without any automated control (= Reference room). Young healthy participants (n = 34) spent five consecutive workdays in each room, where individual light exposure data, skin temperatures and saliva samples for melatonin and cortisol assessments were collected. Vertical illuminance in the Test room was 1177 ± 562 photopic lux (mean ± SD) , which was 320 lux higher than in the Reference room (p < 0.01). Melanopic equivalent daylight (D65) illuminance was 931 ± 484 melanopic lux in the Test room and 730 ± 390 melanopic lux in the Reference room (p < 0.01). Individual light exposures resulted in a 50 min earlier time of half-maximum accumulated illuminance in the Test than the Reference room (p < 0.05). The melatonin secretion onset and peripheral heat loss in the evening occurred significantly earlier with respect to habitual sleeptime in the Test compared to the Reference room (p < 0.05). Our findings suggest that optimized dynamic workplace lighting has the potential to promote earlier melatonin onset and peripheral heat loss prior bedtime, which may be beneficial for persons with a delayed circadian timing system.
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Affiliation(s)
- Marta Benedetti
- Solar Energy and Building Physics Laboratory (LESO-PB), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland.
| | - Lenka Maierová
- University Centre for Energy Efficient Buildings (UCEEB), Czech Technical University in Prague, Trinecka 1024, 27343, Bustehrad, Czech Republic
| | - Christian Cajochen
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Wilhelm Klein-Strasse 27, 4002, Basel, Switzerland
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Jean-Louis Scartezzini
- Solar Energy and Building Physics Laboratory (LESO-PB), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015, Lausanne, Switzerland
| | - Mirjam Münch
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, Wilhelm Klein-Strasse 27, 4002, Basel, Switzerland.
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland.
- Research Centre for Hauora and Health, Massey University, Wellington, New Zealand.
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17
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Brown TM, Brainard GC, Cajochen C, Czeisler CA, Hanifin JP, Lockley SW, Lucas RJ, Münch M, O’Hagan JB, Peirson SN, Price LLA, Roenneberg T, Schlangen LJM, Skene DJ, Spitschan M, Vetter C, Zee PC, Wright KP. Recommendations for daytime, evening, and nighttime indoor light exposure to best support physiology, sleep, and wakefulness in healthy adults. PLoS Biol 2022; 20:e3001571. [PMID: 35298459 PMCID: PMC8929548 DOI: 10.1371/journal.pbio.3001571] [Citation(s) in RCA: 94] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice.
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Affiliation(s)
- Timothy M. Brown
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - George C. Brainard
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Christian Cajochen
- Centre for Chronobiology, University Psychiatric Clinics Basel, Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
| | - Charles A. Czeisler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - John P. Hanifin
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Steven W. Lockley
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Robert J. Lucas
- Centre for Biological Timing, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Mirjam Münch
- Centre for Chronobiology, University Psychiatric Clinics Basel, Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Basel, Switzerland
- Research Centre for Hauora and Health, Massey University, Wellington, New Zealand
| | - John B. O’Hagan
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, United Kingdom
| | - Stuart N. Peirson
- Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Luke L. A. Price
- Centre for Radiation, Chemical and Environmental Hazards, Public Health England, Chilton, Didcot, United Kingdom
| | - Till Roenneberg
- Institutes for Medical Psychology and Occupational, Social and Environmental Medicine, Medical Faculty, Ludwig-Maximilians University (LMU), Munich, Germany
| | - Luc J. M. Schlangen
- Human Technology Interaction Group, Department of Industrial Engineering and Innovation Sciences, Eindhoven University of Technology, Eindhoven, the Netherlands
- Intelligent Lighting Institute, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Debra J. Skene
- Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Manuel Spitschan
- Translational Sensory & Circadian Neuroscience, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
- TUM Department of Sport and Health Sciences (TUM SG), Technical University of Munich, Munich, Germany
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Céline Vetter
- Circadian and Sleep Epidemiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Phyllis C. Zee
- Department of Neurology, Northwestern University, Chicago, Illinois, United States of America
- Center for Circadian and Sleep Medicine, Northwestern University, Chicago, Illinois, United States of America
| | - Kenneth P. Wright
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, Boulder, Colorado, United States of America
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Kundel V, Agyapong PD, Parekh A, Kaali S, Prah RKD, Taweesedt P, Tawiah T, Ayappa I, Mujtaba MN, Agyei O, Jack D, Osei M, Kwarteng AA, Lee A, Asante KP. Characterizing sleep-wake patterns in mothers and children in an agrarian community: results from the Ghana Randomized Air Pollution and Health Study. Sleep 2022; 45:6526421. [PMID: 35143676 PMCID: PMC9366631 DOI: 10.1093/sleep/zsac033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 01/13/2022] [Indexed: 11/15/2022] Open
Abstract
STUDY OBJECTIVES Several studies have examined sleep patterns in rural/indigenous communities, however little is known about sleep characteristics in women of reproductive age, and children within these populations. We investigate sleep-wake patterns in mothers and children (ages 3-5 years) leveraging data from the Ghana Randomized Air Pollution and Health Study (GRAPHS). METHODS The GRAPHS cohort comprises of rural/agrarian communities in Ghana and collected multiday actigraphy in a subset of women and children to assess objective sleep-wake patterns. Data were scored using the Cole-Kripke and Sadeh algorithms for mothers/children. We report descriptive, baseline characteristics and objective sleep measures, compared by access to electricity/poverty status. RESULTS We analyzed data for 58 mothers (mean age 33 ± 6.6) and 64 children (mean age 4 ± 0.4). For mothers, mean bedtime was 9:40 pm ± 56 min, risetime 5:46 am ± 40 min, and total sleep time (TST) was 6.3 h ± 46 min. For children, median bedtime was 8:07 pm (interquartile range [IQR]: 7:50,8:43), risetime 6:09 am (IQR: 5:50,6:37), and mean 24-h TST 10.44 h ± 78 min. Children with access to electricity had a reduced TST compared to those without electricity (p = 0.02). Mean bedtime was later for both mothers (p = 0.05) and children (p = 0.08) classified as poor. CONCLUSIONS Mothers in our cohort demonstrated a shorter TST, and earlier bed/risetimes compared to adults in postindustrialized nations. In contrast, children had a higher TST compared to children in postindustrialized nations, also with earlier sleep-onset and offset times. Investigating objective sleep-wake patterns in rural/indigenous communities can highlight important differences in sleep health related to sex, race/ethnicity, and socioeconomic status, and help estimate the impact of industrialization on sleep in developed countries.
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Affiliation(s)
- Vaishnavi Kundel
- Corresponding author. Vaishnavi Kundel, Icahn School of Medicine at Mount Sinai, Division of Pulmonary, Critical Care and Sleep, One Gustave L Levy Place, Box 1232, New York, NY 10029, USA.
| | - Prince Darko Agyapong
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | - Ankit Parekh
- Icahn School of Medicine at Mount Sinai, Division of Pulmonary, Critical Care and Sleep Medicine, New York, NY, USA
| | - Seyram Kaali
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | | | - Pahnwat Taweesedt
- Division of Pulmonary Medicine, Corpus Christi Medical Center, Corpus Christi, TX, USA
| | - Theresa Tawiah
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | - Indu Ayappa
- Icahn School of Medicine at Mount Sinai, Division of Pulmonary, Critical Care and Sleep Medicine, New York, NY, USA
| | - Mohammed Nuhu Mujtaba
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | - Oscar Agyei
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | - Darby Jack
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, USA
| | - Musah Osei
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
| | | | - Alison Lee
- Icahn School of Medicine at Mount Sinai, Division of Pulmonary, Critical Care and Sleep Medicine, New York, NY, USA
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Ghana Health Service, Brong Ahafo Region, Kintampo, Ghana
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Fernandez FX. Current Insights into Optimal Lighting for Promoting Sleep and Circadian Health: Brighter Days and the Importance of Sunlight in the Built Environment. Nat Sci Sleep 2022; 14:25-39. [PMID: 35023979 PMCID: PMC8747801 DOI: 10.2147/nss.s251712] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Accepted: 12/14/2021] [Indexed: 12/14/2022] Open
Abstract
This perspective considers the possibility that daytime's intrusion into night made possible by electric lighting may not be as pernicious to sleep and circadian health as the encroachment of nighttime into day wrought by 20th century architectural practices that have left many people estranged from sunlight.
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20
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Casiraghi L, de la Iglesia HO. Sleep Under Preindustrial Conditions: What We Can Learn from It. Methods Mol Biol 2022; 2482:1-14. [PMID: 35610416 DOI: 10.1007/978-1-0716-2249-0_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Human sleep is regulated by light in two fundamental ways: The light-dark (LD) cycle entrains a circadian clock that in turn regulates sleep timing, and light per se can acutely inhibit sleep. Throughout evolution, these sleep regulatory systems became highly sensitive to the effects of light and they can be affected by the relatively low light intensities that are used indoors. Thus, postindustrial living conditions have created built environments that have isolated humans from the natural LD cycle and exposed them to an artificial one that can affect daily sleep timing. Studying indigenous communities that have differential access to electricity, as well as communities living in highly urbanized areas, we and others have shown that human access to artificial light has delayed the daily onset of sleep but has had a smaller effect on its offset, leading to an overall reduction in sleep duration that is pervasive in modern societies. In this chapter we discuss these studies, highlight their main findings, and point to their limitations.
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21
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Fischer D, Hilditch CJ. Light in ecological settings: Entrainment, circadian disruption, and interventions. PROGRESS IN BRAIN RESEARCH 2022; 273:303-330. [DOI: 10.1016/bs.pbr.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The human sleep pattern is paradoxical. Sleep is vital for optimal physical and cognitive performance, yet humans sleep the least of all primates. In addition, consolidated and continuous monophasic sleep is evidently advantageous, yet emerging comparative data sets from small-scale societies show that the phasing of the human pattern of sleep–wake activity is highly variable and characterized by significant nighttime activity. To reconcile these phenomena, the social sleep hypothesis proposes that extant traits of human sleep emerged because of social and technological niche construction. Specifically, sleep sites function as a type of social shelter by way of an extended structure of social groups that increases fitness. Short, high-quality, and flexibly timed sleep likely originated as a response to predation risks while sleeping terrestrially. This practice may have been a necessary preadaptation for migration out of Africa and for survival in ecological niches that penetrate latitudes with the greatest seasonal variation in light and temperature on the planet.
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Affiliation(s)
- David R. Samson
- Department of Anthropology, University of Toronto, Mississauga, Ontario L5L 1C6, Canada
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23
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Duarte LL, Menna-Barreto L. Chronotypes and circadian rhythms in university students. BIOL RHYTHM RES 2021. [DOI: 10.1080/09291016.2021.1903791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Leandro L. Duarte
- Laboratório De Estudos Em Neurociências, Cronobiologia & Sono. Centro De Ciências Da Saúde, Universidade Federal Do Recôncavo Da Bahia, Santo Antônio De Jesus, BA, Brasil
| | - Luiz Menna-Barreto
- Escola De Artes Ciências E Humanidades, Universidade De São Paulo, São Paulo, SP, Brasil
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Casiraghi L, Spiousas I, Dunster GP, McGlothlen K, Fernández-Duque E, Valeggia C, de la Iglesia HO. Moonstruck sleep: Synchronization of human sleep with the moon cycle under field conditions. SCIENCE ADVANCES 2021; 7:eabe0465. [PMID: 33571126 PMCID: PMC7840136 DOI: 10.1126/sciadv.abe0465] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/17/2020] [Indexed: 05/20/2023]
Abstract
Before the availability of artificial light, moonlight was the only source of light sufficient to stimulate nighttime activity; still, evidence for the modulation of sleep timing by lunar phases is controversial. Here, we use wrist actimetry to show a clear synchronization of nocturnal sleep timing with the lunar cycle in participants living in environments that range from a rural setting with and without access to electricity in indigenous Toba/Qom communities in Argentina to a highly urbanized postindustrial setting in the United States. Our results show that sleep starts later and is shorter on the nights before the full moon when moonlight is available during the hours following dusk. Our data suggest that moonlight likely stimulated nocturnal activity and inhibited sleep in preindustrial communities and that access to artificial light may emulate the ancestral effect of early-night moonlight.
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Affiliation(s)
| | - Ignacio Spiousas
- Sensorimotor Dynamics Lab (LDSM), CONICET, Universidad Nacional de Quilmes, Bernal, Argentina
| | - Gideon P Dunster
- Department of Biology, University of Washington, Seattle, WA, USA
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25
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Samson DR. Taking the sleep lab to the field: Biometric techniques for quantifying sleep and circadian rhythms in humans. Am J Hum Biol 2020; 33:e23541. [PMID: 33252177 DOI: 10.1002/ajhb.23541] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/12/2020] [Accepted: 11/13/2020] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVES Remarkably, the specifics of sleep along the human lineage have been slow to emerge, which is surprising given our distinct mental and behavioral capacity and the importance of sleep for individual health and cognitive performance. Largely due to difficultly of measuring sleep outside a controlled, clinical, and laboratory study in ambulatory individuals, human biologists have yet to undergo a thorough examination of sleep in ecologically diverse settings. Here, I outline the procedures and methods for generating sleep data in a broader ecological context with the goal of facilitating the integration of sleep and circadian analyses into human biology research. METHODS I describe the steps involved in participant recruitment, screening by way of survey instruments, and sample collection. In addition to describing field use of the traditional (but invasive) equipment such as the gold-standard application of electroencephalography (EEG), I demonstrate leading-edge noninvasive techniques for biometric devices (ie, wrist-worn actigraphy, ring worn arterial pulsometry) to generate sleep and circadian rhythms data. RESULTS I outline best approaches to process and analyze data-including variables such as sleep duration, 24-hour sleep time (ie, summation of night and day sleep), sleep efficiency, sleep fragmentation, and nonparametric circadian rhythms analysis to quantify circadian amplitude. Finally, I discuss comparative statistical methods that are optimized for the use of time-series data. CONCLUSIONS This review serves as an introduction to the best practices for studying sleep-wake patterns in humans-with the goal of standardizing tools for launching new human sleep biology research initiatives across the globe.
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Affiliation(s)
- David R Samson
- Department of Anthropology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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26
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Casiraghi LP, Plano SA, Fernández-Duque E, Valeggia C, Golombek DA, de la Iglesia HO. Access to electric light is associated with delays of the dim-light melatonin onset in a traditionally hunter-gatherer Toba/Qom community. J Pineal Res 2020; 69:e12689. [PMID: 32761922 DOI: 10.1111/jpi.12689] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 11/30/2022]
Abstract
Key to the transition of humans from nomadic hunting-gathering groups to industrialized and highly urbanized societies was the creation of protected and artificially lit environments that extended the natural daylight hours and consolidated sleep away from nocturnal threats. These conditions isolated humans from the natural regulators of sleep and exposed them to higher levels of light during the evening, which are associated with a later sleep onset. Here, we investigated the extent to which this delayed timing of sleep is due to a delayed circadian system. We studied two communities of Toba/Qom in the northern region of Argentina, one with and the other without access to electricity. These communities have recently transitioned from a hunting-gathering subsistence to mixed subsistence systems and represent a unique model in which to study the potential effects of the access to artificial light on sleep physiology. We have previously shown that participants in the community with access to electricity had, compared to participants in the community without electricity, later sleep onsets, and shorter sleep bouts. Here, we show they also have a delayed dim-light melatonin onset (DLMO). This difference is present during the winter but not during the spring when the influence of evening artificial light is likely less relevant. Our results support the notion that the human transition into artificially lit environments had a major impact on physiological systems that regulate sleep timing, including the phase of the master circadian clock.
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Affiliation(s)
| | - Santiago A Plano
- Institute for Biomedical Research (BIOMED), Catholic University of Argentina/CONICET, Buenos Aires, Argentina
- Universidad Nacional de Quilmes/CONICET, Buenos Aires, Argentina
| | - Eduardo Fernández-Duque
- Department of Anthropology and School of Forestry and Environmental Studies, Yale University, New Haven, CT, USA
| | | | - Diego A Golombek
- Universidad Nacional de Quilmes/CONICET, Buenos Aires, Argentina
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27
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Ruiz FS, Beijamini F, Beale AD, Gonçalves BDSB, Vartanian D, Taporoski TP, Middleton B, Krieger JE, Vallada H, Arendt J, Pereira AC, Knutson KL, Pedrazzoli M, von Schantz M. Early chronotype with advanced activity rhythms and dim light melatonin onset in a rural population. J Pineal Res 2020; 69:e12675. [PMID: 32598502 PMCID: PMC7508839 DOI: 10.1111/jpi.12675] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/11/2020] [Accepted: 06/18/2020] [Indexed: 11/28/2022]
Abstract
Studying communities at different stages of urbanisation and industrialisation can teach us how timing and intensity of light affect the circadian clock under real-life conditions. We have previously described a strong tendency towards morningness in the Baependi Heart Study, located in a small rural town in Brazil. Here, we tested the hypothesis that this morningness tendency is associated with early circadian phase based on objective measurements (as determined by dim light melatonin onset, DLMO, and activity) and light exposure. We also analysed how well the previously collected chronotype questionnaire data were able to predict these DLMO values. The average DLMO observed in 73 participants (40 female) was 20:03 ± 01:21, SD, with an earlier average onset in men (19:38 ± 01:16) than in women (20:24 ± 01:21; P ≤ .01). However, men presented larger phase angle between DLMO and sleep onset time as measured by actigraphy (4.11 hours vs 3.16 hours; P ≤ .01). Correlational analysis indicated associations between light exposure, activity rhythms and DLMO, such that early DLMO was observed in participants with higher exposure to light, higher activity and earlier light exposure. The strongest significant predictor of DLMO was morningness-eveningness questionnaire (MEQ) (beta=-0.35, P ≤ .05), followed by age (beta = -0.47, P ≤ .01). Sex, light exposure and variables derived from the Munich chronotype questionnaire were not significant predictors. Our observations demonstrate that both early sleep patterns and earlier circadian phase have been retained in this small rural town in spite of availability of electrification, in contrast to metropolitan postindustrial areas.
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Affiliation(s)
- Francieli S. Ruiz
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, SP, Brazil
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | - Felipe Beijamini
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, SP, Brazil
- Federal University of Fronteira Sul, Realeza, PR, Brazil
| | - Andrew D. Beale
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | | | - Daniel Vartanian
- School of Arts, Science, and Humanities, University of São Paulo, São Paulo, Brazil
| | - Tâmara P. Taporoski
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, SP, Brazil
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - José E. Krieger
- Incor, University of São Paulo School of Medicine, São Paulo, SP, Brazil
| | - Homero Vallada
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, SP, Brazil
| | - Josephine Arendt
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
| | | | | | - Mario Pedrazzoli
- School of Arts, Science, and Humanities, University of São Paulo, São Paulo, Brazil
| | - Malcolm von Schantz
- Department of Psychiatry, University of São Paulo School of Medicine, São Paulo, SP, Brazil
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey, UK
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28
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Moreno CRC, Wright K, Skene DJ, Louzada FM. Phenotypic plasticity of circadian entrainment under a range of light conditions. Neurobiol Sleep Circadian Rhythms 2020; 9:100055. [PMID: 32923743 PMCID: PMC7475273 DOI: 10.1016/j.nbscr.2020.100055] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 08/18/2020] [Accepted: 08/19/2020] [Indexed: 11/25/2022] Open
Abstract
The response to a zeitgeber, particularly the light/dark cycle, may vary phenotypically. Phenotypic plasticity can be defined as the ability of one genome to express different phenotypes in response to environmental variation. In this opinion paper, we present some evidence that one of the most prominent effects of the introduction of electric light to the everyday life of humans is a significant increase in phenotypic plasticity and differences in interindividual phases of entrainment. We propose that the healthy limits of phenotypic plasticity have been surpassed in contemporary society. Electric light increased phenotypic plasticity in humans and differences in interindividual phases of entrainment. Healthy limits of phenotypic plasticity have been surpassed in contemporary society. The correlation between biological time (DLMO) and behavioral time (MSFsc) is reduced in the population without access to electrical light.
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Affiliation(s)
- C R C Moreno
- School of Public Health, University of São Paulo, Brazil.,Stress Research Institute, Department of Psychology, Stockholm University, Sweden
| | - K Wright
- Sleep and Chronobiology Laboratory, Department of Integrative Physiology, University of Colorado Boulder, USA
| | - D J Skene
- Chronobiology, Faculty of Health & Medical Sciences, University of Surrey, UK
| | - F M Louzada
- Department of Physiology, Federal University of Paraná, Brazil
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29
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Martins AJ, Isherwood CM, Vasconcelos SP, Lowden A, Skene DJ, Moreno CR. The effect of urbanization on sleep, sleep/wake routine, and metabolic health of residents in the Amazon region of Brazil. Chronobiol Int 2020; 37:1335-1343. [DOI: 10.1080/07420528.2020.1802287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
| | | | | | - Arne Lowden
- Stress Research Institute, Department of Psychology, University of Stockholm, Stockholm, Stockholm, Sweden
| | - Debra J. Skene
- Faculty of Health & Medical Sciences, University of Surrey, UK
| | - Claudia R.C. Moreno
- School of Public Health, University of São Paulo, São Paulo, Brazil
- Stress Research Institute, Department of Psychology, University of Stockholm, Stockholm, Stockholm, Sweden
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30
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Verhoeven G. (Pre)Modern sleep. New evidence from the Antwerp criminal court (1715-1795). J Sleep Res 2020; 30:e13099. [PMID: 32529713 DOI: 10.1111/jsr.13099] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 05/12/2020] [Accepted: 05/13/2020] [Indexed: 11/29/2022]
Abstract
Lately, experts have turned to historical evidence to uncover the default mode of our sleep pattern. Even though there are some notable exceptions, most historians use a qualitative methodology based on scattered evidence in diaries, letters, novels, medical treatise and other literary sources. To provide fresh perspective in the debate, the present article develops a more quantitative approach. Drawing fresh evidence from early modern criminal records - viz the eyewitness reports of the Hoge Vierschaer or the local criminal court in Antwerp - we are able to debunk some classic stereotypes about premodern sleep patterns. Data reveal that most 18th -century Antwerpers slept fewer hours than we would expect, slumbered in a monophasic way and rarely if ever took a nap during the day. Moreover, the start and end of sleep were less attuned to the solar cycle than we would imagine. Last but not least, the pattern also shows some fascinating weekly and seasonal variations.
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Affiliation(s)
- Gerrit Verhoeven
- University of Antwerp - Centre for Urban History, Antwerpen, Belgium
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31
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Münch M, Wirz-Justice A, Brown SA, Kantermann T, Martiny K, Stefani O, Vetter C, Wright KP, Wulff K, Skene DJ. The Role of Daylight for Humans: Gaps in Current Knowledge. Clocks Sleep 2020; 2:61-85. [PMID: 33089192 PMCID: PMC7445840 DOI: 10.3390/clockssleep2010008] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/21/2020] [Indexed: 01/04/2023] Open
Abstract
Daylight stems solely from direct, scattered and reflected sunlight, and undergoes dynamic changes in irradiance and spectral power composition due to latitude, time of day, time of year and the nature of the physical environment (reflections, buildings and vegetation). Humans and their ancestors evolved under these natural day/night cycles over millions of years. Electric light, a relatively recent invention, interacts and competes with the natural light-dark cycle to impact human biology. What are the consequences of living in industrialised urban areas with much less daylight and more use of electric light, throughout the day (and at night), on general health and quality of life? In this workshop report, we have classified key gaps of knowledge in daylight research into three main groups: (I) uncertainty as to daylight quantity and quality needed for "optimal" physiological and psychological functioning, (II) lack of consensus on practical measurement and assessment methods and tools for monitoring real (day) light exposure across multiple time scales, and (III) insufficient integration and exchange of daylight knowledge bases from different disciplines. Crucial short and long-term objectives to fill these gaps are proposed.
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Affiliation(s)
- Mirjam Münch
- Sleep/Wake Research Centre, Massey University Wellington, Wellington 6021, New Zealand
| | - Anna Wirz-Justice
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (A.W.-J.); (O.S.)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, 4002 Basel, Switzerland
| | - Steven A. Brown
- Chronobiology and Sleep Research Group, Institute of Pharmacology and Toxicology, University of Zürich, 8057 Zürich, Switzerland;
| | - Thomas Kantermann
- Faculty for Health and Social Affairs, University of Applied Sciences for Economics and Management (FOM), 45141 Essen, Germany;
- SynOpus, 44789 Bochum, Germany
| | - Klaus Martiny
- Psychiatric Center Copenhagen, University of Copenhagen, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Oliver Stefani
- Centre for Chronobiology, Psychiatric Hospital of the University of Basel, 4002 Basel, Switzerland; (A.W.-J.); (O.S.)
- Transfaculty Research Platform Molecular and Cognitive Neurosciences (MCN), University of Basel, 4002 Basel, Switzerland
| | - Céline Vetter
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (C.V.); (K.P.W.J.)
| | - Kenneth P. Wright
- Department of Integrative Physiology, University of Colorado Boulder, Boulder, CO 80309, USA; (C.V.); (K.P.W.J.)
- Division of Endocrinology, Metabolism and Diabetes, University of Colorado, Aurora, CO 80045, USA
| | - Katharina Wulff
- Departments of Radiation Sciences and Molecular Biology, Umeå University, 901 87 Umeå, Sweden;
- Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, 901 87 Umeå, Sweden
| | - Debra J. Skene
- Chronobiology, Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK;
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32
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Tiuganji NM, Nehme P, Marqueze EC, Isherwood CM, Martins AJ, Vasconcelos S, Cipolla-Neto J, Lowden A, Skene DJ, Moreno CRC. Eating Behavior (Duration, Content, and Timing) Among Workers Living under Different Levels of Urbanization. Nutrients 2020; 12:E375. [PMID: 32023914 PMCID: PMC7071231 DOI: 10.3390/nu12020375] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/20/2020] [Accepted: 01/24/2020] [Indexed: 01/22/2023] Open
Abstract
Urbanization has contributed to extended wakefulness, which may in turn be associated with eating over a longer period. Here, we present a field study conducted in four groups with different work hours and places of living in order to investigate eating behavior (duration, content, and timing). Anthropometric measures were taken from the participants (rural (n = 22); town (n = 19); city-day workers (n = 11); city-night workers (n = 14)). In addition, a sociodemographic questionnaire was self-answered and 24-h food recalls were applied for three days. The 24-h food recalls revealed that fat intake varied according to the groups, with the highest consumption by the city-day workers. By contrast, city-day workers had the lowest intake of carbohydrate, whereas the rural group had the highest. In general, all groups had some degree of inadequacy in food consumption. Eating duration was negatively correlated with total energy intake, fat, and protein consumption in the rural and town groups. There was a positive correlation between body mass index and eating duration in both city groups. The rural group had the earliest start time of eating, and this was associated with a lower body mass index. This study suggested that food content and timing, as well as eating duration, differed according to place of living, which in turn may be linked to lifestyle.
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Affiliation(s)
- Natalia M. Tiuganji
- School of Public Health, University of São Paulo, 715 Av. Dr. Arnaldo, São Paulo SP 01246-904, Brazil; (N.M.T.); (P.N.); (E.C.M.); (A.J.M.)
| | - Patricia Nehme
- School of Public Health, University of São Paulo, 715 Av. Dr. Arnaldo, São Paulo SP 01246-904, Brazil; (N.M.T.); (P.N.); (E.C.M.); (A.J.M.)
| | - Elaine C. Marqueze
- School of Public Health, University of São Paulo, 715 Av. Dr. Arnaldo, São Paulo SP 01246-904, Brazil; (N.M.T.); (P.N.); (E.C.M.); (A.J.M.)
- Epidemiology, Public Health Graduate Program, Catholic University of Santos, 300 Av. Conselheiro Nébias, Santos SP 11045-003, Brazil
| | - Cheryl M. Isherwood
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK (D.J.S.)
| | - Andressa J. Martins
- School of Public Health, University of São Paulo, 715 Av. Dr. Arnaldo, São Paulo SP 01246-904, Brazil; (N.M.T.); (P.N.); (E.C.M.); (A.J.M.)
| | - Suleima Vasconcelos
- Department of Health Science and Sports Center, Federal University of Acre, Rodovia BR 364, Km 04–Rio Branco–AC 69920-900, Brazil;
| | - José Cipolla-Neto
- Institute of Biomedical Sciences, University of São Paulo, 1524 Av. Prof. Lineu Prestes, São Paulo SP 05508-000, Brazil;
| | - Arne Lowden
- Stress Research Institute, Department of Psychology, University of Stockholm, SE-106 91 Stockholm, Sweden;
| | - Debra J. Skene
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK (D.J.S.)
| | - Claudia R. C. Moreno
- School of Public Health, University of São Paulo, 715 Av. Dr. Arnaldo, São Paulo SP 01246-904, Brazil; (N.M.T.); (P.N.); (E.C.M.); (A.J.M.)
- Stress Research Institute, Department of Psychology, University of Stockholm, SE-106 91 Stockholm, Sweden;
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Sleep timing and duration in indigenous villages with and without electric lighting on Tanna Island, Vanuatu. Sci Rep 2019; 9:17278. [PMID: 31754265 PMCID: PMC6872597 DOI: 10.1038/s41598-019-53635-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/31/2019] [Indexed: 11/09/2022] Open
Abstract
It has been hypothesized that sleep in the industrialized world is in chronic deficit, due in part to evening light exposure, which delays sleep onset and truncates sleep depending on morning work or school schedules. If so, societies without electricity may sleep longer. However, recent studies of hunter-gatherers and pastoralists living traditional lifestyles without electricity report short sleep compared to industrialized population norms. To further explore the impact of lifestyles and electrification on sleep, we measured sleep by actigraphy in indigenous Melanesians on Tanna Island, Vanuatu, who live traditional subsistence horticultural lifestyles, in villages either with or without access to electricity. Sleep duration was long and efficiency low in both groups, compared to averages from actigraphy studies of industrialized populations. In villages with electricity, light exposure after sunset was increased, sleep onset was delayed, and nocturnal sleep duration was reduced. These effects were driven primarily by breastfeeding mothers living with electric lighting. Relatively long sleep on Tanna may reflect advantages of an environment in which food access is reliable, climate benign, and predators and significant social conflict absent. Despite exposure to outdoor light throughout the day, an effect of artificial evening light was nonetheless detectable on sleep timing and duration.
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Chronotherapeutics: Recognizing the Importance of Timing Factors in the Treatment of Disease and Sleep Disorders. Clin Neuropharmacol 2019; 42:80-87. [PMID: 31082833 DOI: 10.1097/wnf.0000000000000341] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
This review describes the characteristics of a number of pathologies, which are considered from the point of view of chronobiology, that is, the way in which biological processes are expressed throughout the 24-hour day. This perspective is a relatively new way of thinking about disease and additionally about how to treat diseases. It has called attention to the importance of not only the quantity of a drug that is administered but also when it is administered. In addition, the review presents an overview of the emerging clinical strategies known as chronotherapeutics, that is, the effects of the daily scheduling of drug administration and the consequences of the activity and efficacy of therapies that are applied in this manner. This article also reviews innovative ways in which physicians are applying time-specified drug treatment (chronopharmacology) for sleep disorders. Here, we present a systematic description of chronopharmacology as well as definitions of key terms that, we believe, will be helpful for newcomers to the field. It is hoped that greater awareness of this new perspective on pharmacology will promote its adoption by researchers and clinicians.
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35
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Martín-Olalla JM. Scandinavian bed and rise times in the Age of Enlightenment and in the 21st century show similarity, helped by Daylight Saving Time. J Sleep Res 2019; 29:e12916. [PMID: 31475390 DOI: 10.1111/jsr.12916] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 11/28/2022]
Affiliation(s)
- José María Martín-Olalla
- Facultad de Física, Departamento de Física de la Materia Condensada, Universidad de Sevilla, Sevilla, Spain
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36
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Shochat T, Santhi N, Herer P, Flavell SA, Skeldon AC, Dijk DJ. Sleep Timing in Late Autumn and Late Spring Associates With Light Exposure Rather Than Sun Time in College Students. Front Neurosci 2019; 13:882. [PMID: 31555073 PMCID: PMC6724614 DOI: 10.3389/fnins.2019.00882] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/07/2019] [Indexed: 12/11/2022] Open
Abstract
Timing of the human sleep-wake cycle is determined by social constraints, biological processes (sleep homeostasis and circadian rhythmicity) and environmental factors, particularly natural and electrical light exposure. To what extent seasonal changes in the light-dark cycle affect sleep timing and how this varies between weekdays and weekends has not been firmly established. We examined sleep and activity patterns during weekdays and weekends in late autumn (standard time, ST) and late spring (daylight saving time, DST), and expressed their timing in relation to three environmental reference points: clock-time, solar noon (SN) which occurs one clock hour later during DST than ST, and the midpoint of accumulated light exposure (50% LE). Observed sleep timing data were compared to simulated data from a mathematical model for the effects of light on the circadian and homeostatic regulation of sleep. A total of 715 days of sleep timing and light exposure were recorded in 19 undergraduates in a repeated-measures observational study. During each three-week assessment, light and activity were monitored, and self-reported bed and wake times were collected. Light exposure was higher in spring than in autumn. 50% LE did not vary across season, but occurred later on weekends compared to weekdays. Relative to clock-time, bedtime, wake-time, mid-sleep, and midpoint of activity were later on weekends but did not differ across seasons. Relative to SN, sleep and activity measures were earlier in spring than in autumn. Relative to 50% LE, only wake-time and mid-sleep were later on weekends, with no seasonal differences. Individual differences in mid-sleep did not correlate with SN but correlated with 50% LE. Individuals with different habitual bedtimes responded similarly to seasonal changes. Model simulations showed that light exposure patterns are sufficient to explain sleep timing in spring but less so in autumn. The findings indicate that during autumn and spring, the timing of sleep associates with actual light exposure rather than sun time as indexed by SN.
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Affiliation(s)
- Tamar Shochat
- Cheryl Spencer Department of Nursing, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - Nayantara Santhi
- Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Paula Herer
- Cheryl Spencer Department of Nursing, Faculty of Social Welfare and Health Sciences, University of Haifa, Haifa, Israel
| | - Sapphira A. Flavell
- Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Anne C. Skeldon
- Department of Mathematics, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, United Kingdom
| | - Derk-Jan Dijk
- Surrey Sleep Research Centre, Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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37
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Chronotype-Dependent Changes in Sleep Habits Associated with Dim Light Melatonin Onset in the Antarctic Summer. Clocks Sleep 2019; 1:352-366. [PMID: 33089174 PMCID: PMC7445856 DOI: 10.3390/clockssleep1030029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 08/05/2019] [Indexed: 12/31/2022] Open
Abstract
Dim light melatonin onset (DLMO) is the most reliable measure of human central circadian timing. Its modulation by light exposure and chronotype has been scarcely approached. We evaluated the impact of light changes on the interaction between melatonin, sleep, and chronotype in university students (n = 12) between the Antarctic summer (10 days) and the autumn equinox in Montevideo, Uruguay (10 days). Circadian preferences were tested by validated questionnaires. A Morningness–Eveningness Questionnaire average value (47 ± 8.01) was used to separate late and early participants. Daylight exposure (measured by actimetry) was significantly higher in Antarctica versus Montevideo in both sensitive time windows (the morning phase-advancing and the evening phase-delaying). Melatonin was measured in hourly saliva samples (18–24 h) collected in dim light conditions (<30 lx) during the last night of each study period. Early and late participants were exposed to similar amounts of light in both sites and time windows, but only early participants were significantly more exposed during the late evening in Antarctica. Late participants advanced their DLMO with no changes in sleep onset time in Antarctica, while early participants delayed their DLMO and sleep onset time. This different susceptibility to respond to light may be explained by a subtle difference in evening light exposure between chronotypes.
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38
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Kennaway DJ. A critical review of melatonin assays: Past and present. J Pineal Res 2019; 67:e12572. [PMID: 30919486 DOI: 10.1111/jpi.12572] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/04/2019] [Accepted: 03/12/2019] [Indexed: 12/12/2022]
Abstract
There has been increased interest in the measurement of melatonin in plasma and saliva recently either as a marker of circadian phase or to understand the physiological role of melatonin. For both situations, there is a need for a specific assay for melatonin that is sensitive enough to detect low concentrations (<2 pg/mL). Since the mid-1970s, there have been many assays developed to measure melatonin in blood and saliva. Radioimmunoassays and ELISA have predominated because of their relative simplicity and high throughput. In this review, I show that the early radioimmunoassays while providing valuable information about nocturnal melatonin levels in humans, generally produced inaccurate basal (daytime) levels. Mass spectrometry assays, however, have provided us with the target values that immunoassays need to achieve, that is, daytime plasma melatonin levels <1 pg/mL. There are now many contemporary commercial assays available utilising both RIA and ELISA technologies, but not all achieve the standards set by the mass spectrometry assays. The performance of these assays is reviewed. I conclude with recommendations on issues researchers need to consider when conducting melatonin studies, including the importance of time of day of collection, validation of assays, the potential causes of poor assay specificity at low levels, the advantages/disadvantages of using saliva vs plasma and extraction assays vs direct assays, kit manufacturers responsibilities and the reporting requirements when publishing melatonin studies.
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Affiliation(s)
- David J Kennaway
- Robinson Research Institute and Adelaide School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
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39
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Roenneberg T, Pilz LK, Zerbini G, Winnebeck EC. Chronotype and Social Jetlag: A (Self-) Critical Review. BIOLOGY 2019; 8:E54. [PMID: 31336976 PMCID: PMC6784249 DOI: 10.3390/biology8030054] [Citation(s) in RCA: 296] [Impact Index Per Article: 59.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 07/05/2019] [Accepted: 07/08/2019] [Indexed: 11/17/2022]
Abstract
The Munich ChronoType Questionnaire (MCTQ) has now been available for more than 15 years and its original publication has been cited 1240 times (Google Scholar, May 2019). Additionally, its online version, which was available until July 2017, produced almost 300,000 entries from all over the world (MCTQ database). The MCTQ has gone through several versions, has been translated into 13 languages, and has been validated against other more objective measures of daily timing in several independent studies. Besides being used as a method to correlate circadian features of human biology with other factors-ranging from health issues to geographical factors-the MCTQ gave rise to the quantification of old wisdoms, like "teenagers are late", and has produced new concepts, like social jetlag. Some like the MCTQ's simplicity and some view it critically. Therefore, it is time to present a self-critical view on the MCTQ, to address some misunderstandings, and give some definitions of the MCTQ-derived chronotype and the concept of social jetlag.
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Affiliation(s)
- Till Roenneberg
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany.
| | - Luísa K Pilz
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany
- Programa de Pós-Graduação em Psiquiatria e Ciências do Comportamento, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 90035-003, Brazil
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre 90035-903, Brazil
| | - Giulia Zerbini
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany
| | - Eva C Winnebeck
- Institute of Medical Psychology, LMU Munich, 80336 Munich, Germany
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High sensitivity and interindividual variability in the response of the human circadian system to evening light. Proc Natl Acad Sci U S A 2019; 116:12019-12024. [PMID: 31138694 PMCID: PMC6575863 DOI: 10.1073/pnas.1901824116] [Citation(s) in RCA: 202] [Impact Index Per Article: 40.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Electric lighting has fundamentally altered how the human circadian clock synchronizes to the day/night cycle. Exposure to light after dusk is pervasive in the modern world. We examined group-level sensitivity of the circadian system to evening light and the degree to which sensitivity varies between individuals. We found that, on average, humans are highly sensitive to evening light. Specifically, 50% suppression of melatonin occurred at <30 lux, which is comparable to or lower than typical indoor lighting used at night, as well as light produced by electronic devices. Significantly, there was a >50-fold difference in sensitivity to evening light across individuals. Interindividual differences in light sensitivity may explain differential vulnerability to circadian disruption and subsequent impact on human health. Before the invention of electric lighting, humans were primarily exposed to intense (>300 lux) or dim (<30 lux) environmental light—stimuli at extreme ends of the circadian system’s dose–response curve to light. Today, humans spend hours per day exposed to intermediate light intensities (30–300 lux), particularly in the evening. Interindividual differences in sensitivity to evening light in this intensity range could therefore represent a source of vulnerability to circadian disruption by modern lighting. We characterized individual-level dose–response curves to light-induced melatonin suppression using a within-subjects protocol. Fifty-five participants (aged 18–30) were exposed to a dim control (<1 lux) and a range of experimental light levels (10–2,000 lux for 5 h) in the evening. Melatonin suppression was determined for each light level, and the effective dose for 50% suppression (ED50) was computed at individual and group levels. The group-level fitted ED50 was 24.60 lux, indicating that the circadian system is highly sensitive to evening light at typical indoor levels. Light intensities of 10, 30, and 50 lux resulted in later apparent melatonin onsets by 22, 77, and 109 min, respectively. Individual-level ED50 values ranged by over an order of magnitude (6 lux in the most sensitive individual, 350 lux in the least sensitive individual), with a 26% coefficient of variation. These findings demonstrate that the same evening-light environment is registered by the circadian system very differently between individuals. This interindividual variability may be an important factor for determining the circadian clock’s role in human health and disease.
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Facer-Childs ER, Middleton B, Skene DJ, Bagshaw AP. Resetting the late timing of 'night owls' has a positive impact on mental health and performance. Sleep Med 2019; 60:236-247. [PMID: 31202686 DOI: 10.1016/j.sleep.2019.05.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/01/2019] [Accepted: 05/03/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND There is conflict between living according to our endogenous biological rhythms and our external environment, with disruptions resulting in negative consequences to health and performance. This is often documented in shift work and jet lag, but 'societal norms' (eg, typical working hours) can create profound issues for 'night owls', people whose internal biological timing predisposes them to follow an unusually late sleep-wake cycle. Night owls have also been associated with health issues, mood disturbances, poorer performance and increased mortality rates. METHODS This study used a randomized control trial design aimed to shift the late timing of night owls to an earlier time (phase advance), using non-pharmacological, practical interventions in a real-world setting. These interventions targeted light exposure (through earlier wake up/sleep times), fixed meals times, caffeine intake and exercise. RESULTS Overall, participants demonstrated a significant advance of ∼2 h in sleep/wake timings as measured by actigraphy and circadian phase markers (dim light melatonin onset and peak time of the cortisol awakening response), whilst having no adverse effect on sleep duration. Notably, the phase advance was accompanied by significant improvements to self-reported depression and stress, as well as improved cognitive (reaction time) and physical (grip strength) performance measures during the typical 'suboptimal' morning hours. CONCLUSIONS Our findings propose a novel strategy for shifting clock timing towards a pattern that is more aligned to societal demands that could significantly improve elements of performance, mental health and sleep timing in the real world.
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Affiliation(s)
- Elise R Facer-Childs
- School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK; Centre for Human Brain Health, University of Birmingham, Birmingham, B15 2TT, UK; School of Psychology, University of Birmingham, Birmingham, B15 2TT, UK.
| | - Benita Middleton
- Faculty of Health & Medical Sciences, University of Surrey, Guildford, GU2 7XH, UK
| | - Debra J Skene
- Faculty of Health & Medical Sciences, University of Surrey, Guildford, GU2 7XH, UK
| | - Andrew P Bagshaw
- Centre for Human Brain Health, University of Birmingham, Birmingham, B15 2TT, UK; School of Psychology, University of Birmingham, Birmingham, B15 2TT, UK
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Facer-Childs ER, Campos BM, Middleton B, Skene DJ, Bagshaw AP. Circadian phenotype impacts the brain's resting-state functional connectivity, attentional performance, and sleepiness. Sleep 2019; 42:zsz033. [PMID: 30763951 PMCID: PMC6519915 DOI: 10.1093/sleep/zsz033] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 01/07/2019] [Indexed: 01/22/2023] Open
Abstract
INTRODUCTION Functional connectivity (FC) of the human brain's intrinsically connected networks underpins cognitive functioning and disruptions of FC are associated with sleep and neurological disorders. However, there is limited research on the impact of circadian phenotype and time of day on FC. STUDY OBJECTIVES The aim of this study was to investigate resting-state FC of the default mode network (DMN) in Early and Late circadian phenotypes over a socially constrained day. METHODS Thirty-eight healthy individuals (14 male, 22.7 ± 4.2 years) categorized as Early (n = 16) or Late (n = 22) using the Munich ChronoType Questionnaire took part. Following a 2-week baseline of actigraphy coupled with saliva samples for melatonin and cortisol rhythms, participants underwent testing at 14:00 hours, 20:00 hours, and 08:00 hours the following morning. Testing consisted of resting-state functional magnetic resonance imaging (fMRI), a structural T1 scan, attentional cognitive performance tasks, and self-reported daytime sleepiness. Seed-based FC analysis from the medial prefrontal and posterior cingulate cortices of the DMN was performed, compared between groups and linked with behavioral data. RESULTS Fundamental differences in the DMN were observed between Early and Late circadian phenotypes. Resting-state FC of the DMN predicted individual differences in attention and subjective ratings of sleepiness. CONCLUSION Differences in FC of the DMN may underlie the compromised attentional performance and increased sleepiness commonly associated with Late types when they conform to a societally constrained day that does not match their intrinsic circadian phenotype.
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Affiliation(s)
- Elise R Facer-Childs
- School of Biosciences, University of Birmingham, Birmingham, UK
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
- School of Psychology, University of Birmingham, Birmingham, UK
| | - Brunno M Campos
- School of Medical Sciences, University of Campinas, Campinas - SP, Brazil
| | - Benita Middleton
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Debra J Skene
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Andrew P Bagshaw
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
- School of Psychology, University of Birmingham, Birmingham, UK
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Martín-Olalla JM. Seasonal synchronization of sleep timing in industrial and pre-industrial societies. Sci Rep 2019; 9:6772. [PMID: 31043654 PMCID: PMC6494851 DOI: 10.1038/s41598-019-43220-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 04/18/2019] [Indexed: 11/09/2022] Open
Abstract
Artificial light has reshaped human sleep/wake cycle in industrial societies and raised concern on the misalignment of this cycle relative to the light and dark cycle. This manuscript contrasts sleep timing in extratropical, industrial societies (data from eight national time use surveys in countries with Daylight Saving Time —DST— regulations) and Subtropical, pre-industrial societies with and without access to artificial light (data from nine locations coming from seven previous reports) against the cycle of light and dark. Within the two process model of sleep, results show sleep onset and sleep offset keep bound to each other by the homeostatic process. In winter, the photoreceptive process aligns the phase of the sleep/wake cycle to sunrise. As a result the phase increasingly lags with increasing latitude up to a delay of 120 min at 55° latitude. In summer, the homeostatic process still binds sleep onset to speep offset but DST rules in industrialized societies reduce the lag by one third to 40 min at 55° latitude. Sleep timing is then stationary with latitude. The phase of the sleep/wake cycle is then governed by natural trends and no clues of misalignment are revealed.
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Affiliation(s)
- José María Martín-Olalla
- Universidad de Sevilla, Facultad de Física, Departamento de Física de la Materia Condensada, ES41012, Seville, Spain.
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LOWDEN A, ÖZTÜRK G, REYNOLDS A, BJORVATN B. Working Time Society consensus statements: Evidence based interventions using light to improve circadian adaptation to working hours. INDUSTRIAL HEALTH 2019; 57:213-227. [PMID: 30700675 PMCID: PMC6449639 DOI: 10.2486/indhealth.sw-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Interventions and strategies to improve health through the management of circadian (re) adaptation have been explored in the field, and in both human and animal laboratory manipulations of shiftwork. As part of an initiative by the Working Time Society (WTS) and International Committee on Occupational Health (ICOH), this review summarises the literature on the management of circadian (re) adaption using bright light treatment. Recommendations to maximise circadian adaptation are summarised for practitioners based on a variety of shiftwork schedules. In slowly rotating night shift schedules bright light appears most suitable when used in connection with the first three night shifts. These interventions are improved when combined with orange glasses (to block blue-green light exposure) for the commute home. Non-shifting strategies involve a lower dosage of light at night and promoting natural daylight exposure during the day (also recommended for day shifts) in acordance with the phase and amplitude response curves to light in humans.
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Affiliation(s)
- Arne LOWDEN
- Stress Research Institute, Stockholm University, Sweden
- *To whom correspondence should be addressed. E-mail:
| | - Gülcin ÖZTÜRK
- Stress Research Institute, Stockholm University, Sweden
| | | | - Bjørn BJORVATN
- Department of Global Public Health and Primary Care,
University of Bergen, Norway
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45
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Martín-Olalla JM. Comment to "Impact of Daylight Saving Time on circadian timing system: An expert statement". Eur J Intern Med 2019; 62:e18-e19. [PMID: 30795882 DOI: 10.1016/j.ejim.2019.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 02/10/2019] [Indexed: 02/05/2023]
Affiliation(s)
- José María Martín-Olalla
- Universidad de Sevilla, Facultad de Física, Departamento de Física de la Materia Condensada, ES41012 Sevilla, Spain.
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Yetish G, Kaplan H, Gurven M. Sleep variability and nighttime activity among Tsimane forager-horticulturalists. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:590-600. [PMID: 29989163 DOI: 10.1002/ajpa.23454] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 02/24/2018] [Accepted: 02/26/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVES A common presumption in sleep research is that "normal" human sleep should show high night-to-night consistency. Yet, intra-individual sleep variation in small-scale subsistence societies has never been studied to test this idea. In this study, we assessed the degree of nightly variation in sleep patterns among Tsimane forager-horticulturalists in Bolivia, and explored possible drivers of the intra-individual variability. METHODS We actigraphically recorded sleep among 120 Tsimane adults (67 female), aged 18-91, for an average of 4.9 nights per person using the Actigraph GT3X and Philips Respironics Actiwatch 2. We assessed intra-individual variation using intra-class correlations and average deviation from each individual's average sleep duration, onset, and offset times ( ɛ¯). RESULTS Only 31% of total variation in sleep duration was due to differences among different individuals, with the remaining 69% due to nightly differences within the same individuals. We found no statistically significant differences in Tsimane sleep duration by day-of-the-week. Nightly variation in sleep duration was driven by highly variable sleep onset, especially for men. Nighttime activities associated with later sleep onset included hunting, fishing, housework, and watching TV. CONCLUSIONS In contrast to nightly sleep variation in the United States being driven primarily by "sleeping-in" on weekends, Tsimane sleep variation, while comparable to that observed in the United States, was driven by changing "bedtimes," independent of day-of-the-week. We propose that this variation may reflect adaptive responses to changing opportunity costs to sleep/nighttime activity.
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Affiliation(s)
- Gandhi Yetish
- Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, California, United States of America
| | - Hillard Kaplan
- Economic Science Institute, Chapman University, Orange, California, United States of America
| | - Michael Gurven
- Department of Anthropology, University of California, Santa Barbara, Santa Barbara, California, United States of America
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Tagg N, McCarthy M, Dieguez P, Bocksberger G, Willie J, Mundry R, Stewart F, Arandjelovic M, Widness J, Landsmann A, Agbor A, Angedakin S, Ayimisin AE, Bessone M, Brazzola G, Corogenes K, Deschner T, Dilambaka E, Eno-Nku M, Eshuis H, Goedmakers A, Granjon AC, Head J, Hermans V, Jones S, Kadam P, Kambi M, Langergraber KE, Lapeyre V, Lapuente J, Lee K, Leinert V, Maretti G, Marrocoli S, Meier A, Nicholl S, Normand E, Ormsby LJ, Piel A, Robinson O, Sommer V, Ter Heegde M, Tickle A, Ton E, van Schijndel J, Vanleeuwe H, Vergnes V, Wessling E, Wittig RM, Zuberbuehler K, Kuehl H, Boesch C. Nocturnal activity in wild chimpanzees (Pan troglodytes): Evidence for flexible sleeping patterns and insights into human evolution. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:510-529. [PMID: 29989158 DOI: 10.1002/ajpa.23478] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Revised: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 02/02/2023]
Abstract
OBJECTIVES We investigated occurrences and patterns of terrestrial nocturnal activity in wild chimpanzees (Pan troglodytes) and modelled the influence of various ecological predictors on nocturnal activity. METHODS Data were extracted from terrestrial camera-trap footage and ecological surveys from 22 chimpanzee study sites participating in the Pan African Programme: The Cultured Chimpanzee. We described videos demonstrating nocturnal activity, and we tested the effects of the percentage of forest, abundance of predators (lions, leopards and hyenas), abundance of large mammals (buffalos and elephants), average daily temperature, rainfall, human activity, and percent illumination on the probability of nocturnal activity. RESULTS We found terrestrial nocturnal activity to occur at 18 of the 22 study sites, at an overall average proportion of 1.80% of total chimpanzee activity, and to occur during all hours of the night, but more frequently during twilight hours. We found a higher probability of nocturnal activity with lower levels of human activity, higher average daily temperature, and at sites with a larger percentage of forest. We found no effect of the abundance of predators and large mammals, rainfall, or moon illumination. DISCUSSION Chimpanzee terrestrial nocturnal activity appears widespread yet infrequent, which suggests a consolidated sleeping pattern. Nocturnal activity may be driven by the stress of high daily temperatures and may be enabled at low levels of human activity. Human activity may exert a relatively greater influence on chimpanzee nocturnal behavior than predator presence. We suggest that chimpanzee nocturnal activity is flexible, enabling them to respond to changing environmental factors.
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Affiliation(s)
- Nikki Tagg
- Antwerp Zoo Centre for Research and Conservation, Royal Zoological Society of Antwerp, Belgium
| | - Maureen McCarthy
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Paula Dieguez
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | - Jacob Willie
- Antwerp Zoo Centre for Research and Conservation, Royal Zoological Society of Antwerp, Belgium
- Terrestrial Ecology Department, University of Gent, Belgium
| | - Roger Mundry
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Fiona Stewart
- School of Natural Sciences and Psychology, University of Liverpool, Liverpool, United Kingdom
| | - Mimi Arandjelovic
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Jane Widness
- Department of Anthropology, Yale University, New Haven, Connecticut
| | - Anja Landsmann
- University Medical Center, University of Leipzig, Leipzig, Germany
| | - Anthony Agbor
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Samuel Angedakin
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | - Mattia Bessone
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Gregory Brazzola
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | - Tobias Deschner
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | | | - Henk Eshuis
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | | | - Josephine Head
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Veerle Hermans
- Antwerp Zoo Centre for Research and Conservation, Royal Zoological Society of Antwerp, Belgium
| | - Sorrel Jones
- School of Biological Sciences, Royal Holloway University of London, Egham, United Kingdom
| | - Parag Kadam
- Faculty of Forestry, University of Toronto, Toronto, Canada
| | - Mohamed Kambi
- Pennsylvania State University (USA), Tanzania Program, c/o Udzungwa Mountains National Park, Kilombero, Tanzania
| | - Kevin E Langergraber
- School of Human Evolution and Social Change, Arizona State University, Tempe, Arizona
| | - Vincent Lapeyre
- Wild Chimpanzee Foundation (WCF), Abidjan, Côte d'Ivoire, Africa
| | - Juan Lapuente
- Comoé Chimpanzee Conservation Project, Comoé Research Station, Animal Ecology and Tropical Biology, Biozentrum, Universität Würzburg Tierökologie und Tropenbiologie (Zoologie III), Würzburg, Germany
| | - Kevin Lee
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Vera Leinert
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Giovanna Maretti
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Sergio Marrocoli
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Amelia Meier
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Nicholas School of the Environment, Duke University, Durham
| | - Sonia Nicholl
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | | | - Lucy Jayne Ormsby
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Alex Piel
- School of Natural Sciences and Psychology Liverpool John Moores University, Liverpool, United Kingdom
| | - Orume Robinson
- Korup Rainforest Conservation Society, Mundemba, Cameroon, Africa
| | - Volker Sommer
- Department of Anthropology, University College London, London, United Kingdom
| | - Martijn Ter Heegde
- KfW Biodiversity Conservation and Sustainable Forest Management Program for GFA Consulting Group, Kinshasa, Democratic Republic of the Congo, Africa
| | - Alexander Tickle
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Els Ton
- Chimbo Foundation, Amsterdam, The Netherlands
| | | | | | - Virginie Vergnes
- Wild Chimpanzee Foundation (WCF), Abidjan, Côte d'Ivoire, Africa
| | - Erin Wessling
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany
| | - Roman M Wittig
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- Taï Chimpanzee Project, Centre Suisse des Recherche Scientifique, Abidjan, Côte d'Ivoire, Africa
| | | | - Hjalmar Kuehl
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany
| | - Christophe Boesch
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Leypunskiy E, Kıcıman E, Shah M, Walch OJ, Rzhetsky A, Dinner AR, Rust MJ. Geographically Resolved Rhythms in Twitter Use Reveal Social Pressures on Daily Activity Patterns. Curr Biol 2018; 28:3763-3775.e5. [PMID: 30449672 PMCID: PMC6590897 DOI: 10.1016/j.cub.2018.10.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 08/22/2018] [Accepted: 10/04/2018] [Indexed: 12/31/2022]
Abstract
Daily rhythms in human physiology and behavior are driven by the interplay of circadian rhythms, environmental cycles, and social schedules. Much research has focused on the mechanism and function of circadian rhythms in constant conditions or in idealized light-dark environments. There have been comparatively few studies into how social pressures, such as work and school schedules, affect human activity rhythms day to day and season to season. To address this issue, we analyzed activity on Twitter in >1,500 US counties throughout the 2012-2013 calendar years in 15-min intervals using geographically tagged tweets representing ≈0.1% of the total population each day. We find that sustained periods of low Twitter activity are correlated with sufficient sleep as measured by conventional surveys. We show that this nighttime lull in Twitter activity is shifted to later times on weekends relative to weekdays, a phenomenon we term "Twitter social jet lag." The magnitude of this social jet lag varies seasonally and geographically-with the West Coast experiencing less Twitter social jet lag compared to the Central and Eastern US-and is correlated with average commuting schedules and disease risk factors such as obesity. Most counties experience the largest amount of Twitter social jet lag in February and the lowest in June or July. We present evidence that these shifts in weekday activity coincide with relaxed social pressures due to local K-12 school holidays and that the direct seasonal effect of altered day length is comparatively weaker.
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Affiliation(s)
- Eugene Leypunskiy
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, IL 60637, USA
| | - Emre Kıcıman
- Information and Data Science Group, Microsoft Research, Redmond, WA, 98052, USA
| | - Mili Shah
- The University of Chicago Laboratory Schools, Chicago, IL 60637, USA
| | - Olivia J Walch
- Department of Mathematics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Andrey Rzhetsky
- Departments of Medicine and Human Genetics, The University of Chicago, Chicago, IL 60637, USA
| | - Aaron R Dinner
- Department of Chemistry and the James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | - Michael J Rust
- Department of Molecular Genetics and Cell Biology and Department of Physics, The University of Chicago, Chicago, IL 60637, USA.
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Facer-Childs ER, Boiling S, Balanos GM. The effects of time of day and chronotype on cognitive and physical performance in healthy volunteers. SPORTS MEDICINE-OPEN 2018; 4:47. [PMID: 30357501 PMCID: PMC6200828 DOI: 10.1186/s40798-018-0162-z] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 10/14/2018] [Indexed: 11/24/2022]
Abstract
Background Whether you are a morning lark or a night owl has proven to be a key contributor in the timing of peak athletic performance. Recent evidence suggests that accounting for these differences, known as one’s chronotype, results in significantly different diurnal performance profiles. However, there is limited research investigating multiple measures of performance simultaneously over the course of a socially constrained day. Objectives This study aimed to investigate the impact of chronotype on indices of cognitive and physical performance at different times of day in healthy volunteers. Methods We recruited 56 healthy individuals categorised as early (ECT, n = 25) or late (LCT, n = 31) chronotypes using the Munich ChronoType Questionnaire, circadian phase markers and objective actigraphy. Measures of cognitive and physical performance, along with self-reported daytime sleepiness, were taken at multiple times of day (14:00 h, 20:00 h and 08:00 h the following morning). Results Here, we find significantly different diurnal variation profiles between ECTs and LCTs, for daytime sleepiness, psychomotor vigilance, executive function and isometric grip strength. LCTs were significantly impaired in all measures in the morning compared to ECTs. Conclusion Our results provide evidence to support the notion that ‘night owls’ are compromised earlier in the day. We offer new insight into how differences in habitual sleep patterns and circadian rhythms impact cognitive and physical measures of performance. These findings may have implications for the sports world, e.g. athletes, coaches and teams, who are constantly looking for ways to minimise performance deficits and maximise performance gains.
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Affiliation(s)
- Elise R Facer-Childs
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. .,School of Psychology, Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
| | - Sophie Boiling
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - George M Balanos
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Pilz LK, Levandovski R, Oliveira MAB, Hidalgo MP, Roenneberg T. Sleep and light exposure across different levels of urbanisation in Brazilian communities. Sci Rep 2018; 8:11389. [PMID: 30061685 PMCID: PMC6065379 DOI: 10.1038/s41598-018-29494-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/26/2018] [Indexed: 12/22/2022] Open
Abstract
Quilombos are settlements originally founded by Africans and African descendants (Quilombolas) in remote parts of Brazil to escape slavery. Due to individual histories, Quilombos nowadays exhibit different states of industrialisation, making them ideal for studying the influence of electrification on daily behaviour. In a comparative approach, we aimed to understand whether and how human sleep changes with the introduction of artificial light. We investigated daily rest-activity-rhythms and sleep-patterns in the Quilombolas' by both wrist actimetry and the Munich ChronoType Questionnaire (MCTQ; the results of these two instruments correlated highly). Seven communities (MCTQ: N = 213/actimetry: N = 125) were compared in this study. Light exposure, phase of activity, sleep timing and duration differ across communities with various levels of urbanisation and histories of access to electricity. People living without electricity and those, who acquired it only very recently on average sleep earlier than those in more urbanised communities (mid-sleep about 1 hour earlier); sleep duration tends to be longer. Our results and those of others show that use of electricity and modern lifestyles have changed sleep behaviour. To understand the consequences of these changes for health, further studies are warranted.
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Affiliation(s)
- Luísa K Pilz
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA)/Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Programa de Pós-Graduação em Psiquiatria e Ciências do Comportamento, Faculdade de Medicina - UFRGS, Porto Alegre, RS, Brazil
| | - Rosa Levandovski
- Programa de Pós-Graduação em Avaliação e Produção de Tecnologias para o SUS - GHC, Porto Alegre, RS, Brazil
- Programa de Pós-Graduação em Saúde Coletiva - UFRGS, Porto Alegre, RS, Brazil
| | - Melissa A B Oliveira
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA)/Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Programa de Pós-Graduação em Psiquiatria e Ciências do Comportamento, Faculdade de Medicina - UFRGS, Porto Alegre, RS, Brazil
| | - Maria Paz Hidalgo
- Laboratório de Cronobiologia e Sono, Hospital de Clínicas de Porto Alegre (HCPA)/Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Programa de Pós-Graduação em Psiquiatria e Ciências do Comportamento, Faculdade de Medicina - UFRGS, Porto Alegre, RS, Brazil
| | - Till Roenneberg
- Institute of Medical Psychology, LMU, Munich, BY, Germany.
- Visiting Professor at UFRGS/CAPES, Porto Alegre, RS, Brazil.
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