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Rodríguez Ferrante G, Leone MJ. Solar clock and school start time effects on adolescents' chronotype and sleep: A review of a gap in the literature. J Sleep Res 2024; 33:e13974. [PMID: 37370220 DOI: 10.1111/jsr.13974] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 05/11/2023] [Accepted: 06/11/2023] [Indexed: 06/29/2023]
Abstract
Circadian rhythms are entrained by external factors such as sunlight and social cues, but also depend on internal factors such as age. Adolescents exhibit late chronotypes, but worldwide school starts early in the morning leading to unhealthy sleep habits. Several studies reported that adolescents benefit from later school start times. However, the effect of later school start time on different outcomes varies between studies, and most previous literature only takes into consideration the social clock (i.e. local time of school starting time) but not the solar clock (e.g. the distance between school start time and sunrise). Thus, there is an important gap in the literature: when assessing the effect of a school start time on chronotype and sleep of adolescents at different locations and/or seasons, the solar clock might differ and, consistently, the obtained results. For example, the earliest school start time for adolescents has been suggested to be 08:30 hours, but this school start time might correspond to different solar times at different times of the year, longitudes and latitudes. Here, we describe the available literature comparing different school start times, considering important factors such as geographic position, nationality, and the local school start time and its distance to sunrise. Then, we described and contrasted the relative role of both social and solar clocks on the chronotype and sleep of adolescents. As a whole, we point and discuss a gap in literature, suggesting that both clocks are relevant when addressing the effect of school start time on adolescents' chronotype and sleep.
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Affiliation(s)
- Guadalupe Rodríguez Ferrante
- Laboratorio de Neurociencia, Universidad Torcuato Di Tella, CONICET, Buenos Aires, Argentina
- Laboratorio de Cronobiología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, CONICET, Buenos Aires, Argentina
| | - María Juliana Leone
- Laboratorio de Neurociencia, Universidad Torcuato Di Tella, CONICET, Buenos Aires, Argentina
- Área de Educación, Escuela de Gobierno, Universidad Torcuato Di Tella, Buenos Aires, Argentina
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2
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Malheiros LE, da Costa BG, Lopes MV, Martins da Costa R, Chaput JP, Silva KS. Association of sleep timing and sleep variability with health-related outcomes in a sample of Brazilian adolescents. Behav Sleep Med 2024; 22:129-139. [PMID: 37154038 DOI: 10.1080/15402002.2023.2207699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
OBJECTIVES This cross-sectional study aimed to examine the relationships of sleep timing and sleep variability with depressive symptoms, health-related quality of life (HRQoL), daytime sleepiness, and body mass index (BMI) in adolescents. METHODS Adolescents from three schools (n = 571, 56% female, 16.3 ± 1.0 years) had their sleep examined by actigraphy, their anthropometrics assessed, and answered a survey. Sleep timing was examined by combining groups of median-dichotomized onset and wakeup times (early onset and early wakeup; early onset and late wakeup; later onset and early wakeup; later onset and later wakeup); sleep variability was based on within-participant standard deviations of onset and wakeup; and sleep duration as the length of time between onset and wakeup. The sleep variables were separated for weekdays and weekend. Mixed linear models were fitted to compare each sleep variable with health-related outcomes. RESULTS Higher values of daytime sleepiness were observed in adolescents from the late-early and late-late timing group during the week. Greater sleep midpoint and wakeup variability on weekdays were related with higher daytime sleepiness. Adolescents in the late-late and early-late groups showed higher daytime sleepiness. Increased of all sleep variability variables was related with greater daytime sleepiness. Higher depressive symptoms scores were found among adolescents in the late-early subgroup and with the increase of sleep variability. Participants with greater sleep onset variability and sleep midpoint variability reported less HRQoL. CONCLUSIONS Not only sleep duration, but sleep timing and variability also relate to health outcomes, and should be addressed by policies and interventions among adolescents.
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Affiliation(s)
- Luís Ea Malheiros
- Núcleo de Pesquisa em Atividade Física e Saúde, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Bruno Gg da Costa
- Núcleo de Pesquisa em Atividade Física e Saúde, Universidade Federal de Santa Catarina, Florianópolis, Brazil
- School of Physical and Health Education, Nipissing University, North Bay, Canada
| | - Marcus Vv Lopes
- Núcleo de Pesquisa em Atividade Física e Saúde, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Rafael Martins da Costa
- Núcleo de Pesquisa em Atividade Física e Saúde, Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Jean-Philippe Chaput
- Healthy Active Living and Obesity Research Group, Children's Hospital of Eastern Ontario Research Institute, Ottawa, Ontario, Canada
| | - Kelly S Silva
- Núcleo de Pesquisa em Atividade Física e Saúde, Universidade Federal de Santa Catarina, Florianópolis, Brazil
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3
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Sweeney MR, Nichols HB, Jones RR, Olshan AF, Keil AP, Engel LS, James P, Sandler DP, White AJ, Jackson CL. Exposure to indoor light at night in relation to multiple dimensions of sleep health: findings from the Sister Study. Sleep 2024; 47:zsad100. [PMID: 37018759 PMCID: PMC10851850 DOI: 10.1093/sleep/zsad100] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 02/23/2023] [Indexed: 04/07/2023] Open
Abstract
STUDY OBJECTIVE To examine the association between light at night (LAN) and multiple sleep health dimensions. METHODS Among 47 765 Sister Study participants, indoor LAN (TV on in the room, light(s) on in room, light from outside the room, nightlight, no light) and sleep dimensions were self-reported at baseline (2003-2009). We used Poisson regression with robust variance to estimate adjusted prevalence ratios (PR) and 95% confidence intervals (CI) for the cross-sectional associations between LAN and short sleep duration (<7 hours/night), insomnia symptoms (difficulty falling or staying asleep), frequent napping (≥3 naps/week), inconsistent sleep/wake time (differed day-to-day and week-to-week), sleep debt (≥2 hours between longest and shortest duration), recent sleep medication use, and a cumulative poor sleep score (≥3 poor sleep dimensions). Population-attributable risks (PARs) were determined for any light exposure vs. none by race/ethnicity. RESULTS Compared to sleeping with no light in the bedroom, sleeping with a TV on was associated with a higher prevalence of most dimensions of poor sleep (e.g. short sleep duration: PR = 1.38, 95% CI: 1.32 to 1.45; inconsistent sleep/wake time: PR = 1.55, 95% CI: 1.44 to 1.66; sleep debt: PR = 1.36, 95% CI: 1.29 to 1.44; poor sleep score: PR = 1.58, 95% CI: 1.48-1.68). PARs tended to be higher for non-Hispanic black women compared to non-Hispanic white women. CONCLUSIONS Sleeping with a TV on was associated with poor sleep health among US women, and non-Hispanic black women may be disproportionately burdened.
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Affiliation(s)
- Marina R Sweeney
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Hazel B Nichols
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Rena R Jones
- Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD, USA
| | - Andrew F Olshan
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Alexander P Keil
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Lawrence S Engel
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC, USA
| | - Peter James
- Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, MA, USA
- Department of Environmental Health, Harvard TH Chan School of Public Health, Boston, MA, USA
| | - Dale P Sandler
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Alexandra J White
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
| | - Chandra L Jackson
- Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
- Division of Intramural Research, National Institute on Minority Health and Health Disparities, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA
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4
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Skeldon AC, Rodriguez Garcia T, Cleator SF, della Monica C, Ravindran KKG, Revell VL, Dijk DJ. Method to determine whether sleep phenotypes are driven by endogenous circadian rhythms or environmental light by combining longitudinal data and personalised mathematical models. PLoS Comput Biol 2023; 19:e1011743. [PMID: 38134229 PMCID: PMC10817199 DOI: 10.1371/journal.pcbi.1011743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 01/26/2024] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Sleep timing varies between individuals and can be altered in mental and physical health conditions. Sleep and circadian sleep phenotypes, including circadian rhythm sleep-wake disorders, may be driven by endogenous physiological processes, exogeneous environmental light exposure along with social constraints and behavioural factors. Identifying the relative contributions of these driving factors to different phenotypes is essential for the design of personalised interventions. The timing of the human sleep-wake cycle has been modelled as an interaction of a relaxation oscillator (the sleep homeostat), a stable limit cycle oscillator with a near 24-hour period (the circadian process), man-made light exposure and the natural light-dark cycle generated by the Earth's rotation. However, these models have rarely been used to quantitatively describe sleep at the individual level. Here, we present a new Homeostatic-Circadian-Light model (HCL) which is simpler, more transparent and more computationally efficient than other available models and is designed to run using longitudinal sleep and light exposure data from wearable sensors. We carry out a systematic sensitivity analysis for all model parameters and discuss parameter identifiability. We demonstrate that individual sleep phenotypes in each of 34 older participants (65-83y) can be described by feeding individual participant light exposure patterns into the model and fitting two parameters that capture individual average sleep duration and timing. The fitted parameters describe endogenous drivers of sleep phenotypes. We then quantify exogenous drivers using a novel metric which encodes the circadian phase dependence of the response to light. Combining endogenous and exogeneous drivers better explains individual mean mid-sleep (adjusted R-squared 0.64) than either driver on its own (adjusted R-squared 0.08 and 0.17 respectively). Critically, our model and analysis highlights that different people exhibiting the same sleep phenotype may have different driving factors and opens the door to personalised interventions to regularize sleep-wake timing that are readily implementable with current digital health technology.
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Affiliation(s)
- Anne C. Skeldon
- School of Mathematics & Physics, University of Surrey, Guildford, United Kingdom
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
| | - Thalia Rodriguez Garcia
- School of Mathematics & Physics, University of Surrey, Guildford, United Kingdom
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
| | - Sean F. Cleator
- School of Mathematics & Physics, University of Surrey, Guildford, United Kingdom
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
| | - Ciro della Monica
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
| | - Kiran K. G. Ravindran
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
| | - Victoria L. Revell
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
| | - Derk-Jan Dijk
- UK Dementia Research Institute, Care Research and Technology Centre at Imperial College, London and the University of Surrey, Guildford, United Kingdom
- Surrey Sleep Research Centre, Department of Clinical and Experimental Medicine, University of Surrey, Guildford, United Kingdom
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Willoughby AR, Alikhani I, Karsikas M, Chua XY, Chee MWL. Country differences in nocturnal sleep variability: Observations from a large-scale, long-term sleep wearable study. Sleep Med 2023; 110:155-165. [PMID: 37595432 DOI: 10.1016/j.sleep.2023.08.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/10/2023] [Accepted: 08/09/2023] [Indexed: 08/20/2023]
Abstract
STUDY OBJECTIVES Country or regional differences in sleep duration are well-known, but few large-scale studies have specifically evaluated sleep variability, either across the work week, or in terms of differences in weekday and weekend sleep. METHODS Sleep measures, obtained over 50 million night's sleep from ∼220,000 wearable device users in 35 countries, were analysed. Each person contributed an average of ∼242 nights of data. Multiple regression was used to assess the impact country of residence had on sleep duration, timing, efficiency, weekday sleep variability, weekend sleep extension and social jetlag. RESULTS Nocturnal sleep was shorter and had a later onset in Asia than other regions. Despite this, sleep efficiency was lower and weekday sleep variability was higher. Weekend sleep extension was longer in Europe and the USA than in Asia, and was only partially related to weekday sleep duration. There were also cross-country differences in social jetlag although the regional differences were less distinct than for weekend sleep extension. CONCLUSIONS In addition to regional differences in sleep duration, cross-country differences in sleep variability and weekend sleep extension suggest that using the latter as an indicator of sleep debt may need to be reconsidered. In countries exhibiting both short sleep and high weekday sleep variability, a culturally different means of coping with inadequate sleep is likely. Country or region differences in culture, particularly those related to work, merit closer examination as factors influencing the variability in normative sleep patterns around the world.
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Affiliation(s)
- Adrian R Willoughby
- Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, 12 Science Drive 2, Singapore, 117549, Singapore
| | - Iman Alikhani
- Oura Health Oy, Oulu, Elektroniikkatie 10, 90590, Finland
| | - Mari Karsikas
- Oura Health Oy, Oulu, Elektroniikkatie 10, 90590, Finland
| | - Xin Yu Chua
- Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, 12 Science Drive 2, Singapore, 117549, Singapore
| | - Michael W L Chee
- Centre for Sleep and Cognition, Yong Loo Lin School of Medicine, National University of Singapore, 12 Science Drive 2, Singapore, 117549, Singapore.
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6
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Breda M, Belli A, Esposito D, Di Pilla A, Melegari MG, DelRosso L, Malorgio E, Doria M, Ferri R, Bruni O. Sleep habits and sleep disorders in Italian children and adolescents: a cross-sectional survey. J Clin Sleep Med 2023; 19:659-672. [PMID: 36661089 PMCID: PMC10071380 DOI: 10.5664/jcsm.10400] [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] [Received: 07/13/2022] [Revised: 11/14/2022] [Accepted: 11/14/2022] [Indexed: 01/21/2023]
Abstract
STUDY OBJECTIVES The aim was to describe sleep habits and epidemiology of the most common sleep disorders in Italian children and adolescents. METHODS This was a cross-sectional study in which parents of typically developing children and adolescents (1-18 years) completed an online survey available in Italy, gathering retrospective information focusing on sleep habits and disorders. RESULTS Respondents were 4,321 typically developing individuals (48.6% females). Most of our sample did not meet the age-specific National Sleep Foundation recommendations for total sleep duration (31.9% of toddlers, 71.5% of preschoolers, 61.6% of school-age children, and 41.3% of adolescents). Napping was described in 92.6% of toddlers and in 35.2% of preschoolers. Regarding geographical differences, children and adolescents of northern Italy showed more frequent earlier bedtimes and rise times than their peers of central and southern Italy. The most frequently reported sleep disorder in our sample was restless sleep (35.6%), followed by difficulties falling asleep (16.8%), > 2 night awakenings (9.9%), and bruxism (9.6%). Data also suggest that longer screen time is associated with later bedtimes on weekdays in all age groups. CONCLUSIONS The current study shows that Italian children are at risk of sleep disorders, particularly insufficient sleep, restless sleep, and difficulty falling asleep. The study also provides normative sleep data by age group in a large cohort of typically developing Italian children, emphasizing the importance of the developmentally, ecologically, and culturally based evaluation of sleep habits and disorders. CITATION Breda M, Belli A, Esposito D, et al. Sleep habits and sleep disorders in Italian children and adolescents: a cross-sectional survey. J Clin Sleep Med. 2023;19(4):659-672.
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Affiliation(s)
- Maria Breda
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Arianna Belli
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Dario Esposito
- Child Neurology and Psychiatry Unit, Department of Human Neurosciences, Sapienza University of Rome, Rome, Italy
| | - Andrea Di Pilla
- Life Sciences and Public Health Department, Hygiene Section, Medicine and Surgery “A. Gemelli”—Catholic University of Sacred Heart, Rome, Italy
| | - Maria Grazia Melegari
- Department of Social and Developmental Psychology, Sapienza University of Roma, Rome, Italy
| | - Lourdes DelRosso
- Pulmonary and Sleep Medicine, University of Washington, Seattle Children’s Hospital, Seattle, Washington
| | - Emanuela Malorgio
- Italian Federation of Primary Care Pediatricians (Federazione Italiana Medici Pediatri [FIMP]), Torino, Italy
| | - Mattia Doria
- Italian Federation of Primary Care Pediatricians (Federazione Italiana Medici Pediatri [FIMP]), Venice, Italy
| | - Raffaele Ferri
- Sleep Research Centre, Department of Neurology IC, Oasi Research Institute—IRCCS, Troina, Italy
| | - Oliviero Bruni
- Department of Social and Developmental Psychology, Sapienza University of Roma, Rome, Italy
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7
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Baraniuk C. Why health experts are fighting to end daylight saving time. BMJ 2023; 380:622. [PMID: 36958725 DOI: 10.1136/bmj.p622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/25/2023]
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8
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van den Berg NH, Michaud X, Pattyn N, Simonelli G. How Sleep Research in Extreme Environments Can Inform the Military: Advocating for a Transactional Model of Sleep Adaptation. Curr Psychiatry Rep 2023; 25:73-91. [PMID: 36790725 DOI: 10.1007/s11920-022-01407-3] [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] [Accepted: 12/06/2022] [Indexed: 02/16/2023]
Abstract
PURPOSE OF REVIEW We review the literature on sleep in extreme environments. Accordingly, we present a model that identifies the need for mitigating interventions to preserve sleep quality for military deployments. RECENT FINDINGS Situational factors that affect sleep in extreme environments include cold temperatures, isolated and confined areas, fluctuating seasonality, photoperiodicity, and extreme latitudes and altitudes. Results vary across studies, but general effects include decreased total sleep time, poor sleep efficiency, and non-specific phase delays or phase advances in sleep onset and sleep architecture. Considering habitability measures (e.g., light or temperature control) and individual differences such as variable stress responses or sleep need can mitigate these effects to improve mood, cognition, and operational performance. Although the situational demands during military missions inevitably reduce total sleep time and sleep efficiency, mitigating factors can attenuate sleep-related impairments, hence allowing for optimal mission success and personnel safety.
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Affiliation(s)
- N H van den Berg
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada.,School of Psychology, Faculty of Social Sciences, University of Ottawa, Ottawa, Ontario, Canada
| | - X Michaud
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada.,Department of Psychology, Faculty of Arts and Science, Université de Montréal, Montreal, Quebec, Canada
| | - N Pattyn
- Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.,Human Physiology Department (MFYS), Vrije Universiteit Brussel, Brussels, Belgium.,VIPER Research Unit, Royal Military Academy, Brussels, Belgium
| | - G Simonelli
- Centre d'études avancées en médecine du sommeil, Hôpital du Sacré-Coeur de Montréal, CIUSSS du Nord de l'Île-de-Montréal, Montreal, Quebec, Canada. .,Department of Medicine, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada. .,Department of Neuroscience, Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.
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Coutrot A, Lazar AS, Richards M, Manley E, Wiener JM, Dalton RC, Hornberger M, Spiers HJ. Reported sleep duration reveals segmentation of the adult life-course into three phases. Nat Commun 2022; 13:7697. [PMID: 36509747 PMCID: PMC9744828 DOI: 10.1038/s41467-022-34624-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 11/01/2022] [Indexed: 12/15/2022] Open
Abstract
Classically the human life-course is characterized by youth, middle age and old age. A wide range of biological, health and cognitive functions vary across this life-course. Here, using reported sleep duration from 730,187 participants across 63 countries, we find three distinct phases in the adult human life-course: early adulthood (19-33yrs), mid-adulthood (34-53yrs), and late adulthood (54+yrs). They appear stable across culture, gender, education and other demographics. During the third phase, where self-reported sleep duration increases with age, cognitive performance, as measured by spatial navigation, was found to have an inverted u-shape relationship with reported sleep duration: optimal performance peaks at 7 hours reported sleep. World-wide self-reported sleep duration patterns are geographically clustered, and are associated with economy, culture, and latitude.
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Affiliation(s)
- A Coutrot
- LIRIS-CNRS-University of Lyon, Lyon, France.
| | - A S Lazar
- Norwich Medical School, University of East Anglia, Norwich, UK
| | - M Richards
- Unit for Lifelong Health and Ageing, University College London, London, UK
| | - E Manley
- School of Geography, University of Leeds, Leeds, UK
| | - J M Wiener
- Department of Psychology, Bournemouth University, Poole, UK
| | - R C Dalton
- School of Architecture, Lancaster University, Lancaster, UK
| | - M Hornberger
- Norwich Medical School, University of East Anglia, Norwich, UK.
| | - H J Spiers
- Institute of Behavioural Neuroscience, University College London, London, UK.
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10
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International study of the prevalence and factors associated with insomnia in the general population. Sleep Med 2021; 82:186-192. [PMID: 33957414 DOI: 10.1016/j.sleep.2021.03.028] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/08/2021] [Accepted: 03/26/2021] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Insomnia is a public health problem with many repercussions. It affects a significant proportion of the general population worldwide, but the estimated prevalences in different countries are difficult to compare due to the use of heterogeneous methodologies. The objectives of the study were to compare the prevalence of insomnia in the general population in different sites around the world and to identify sociodemographic and mental health associated factors, using the same tool and within a single study. METHODS This multicenter cross-sectional study is based on the Mental Health in the General Population survey (MHPG). It included several sites in France and 12 countries around the world with a representative sampling of the general population. The prevalence of short-term insomnia disorder was estimated by the occurrence within one month of at least one symptom, at a minimum frequency of three per week, with repercussions on everyday life. RESULTS Out of the 57,298 participants, 11.3% had a diagnosis of short-term insomnia disorder, with significant differences in prevalence between sites, ranging from 2.3% to 25.5%. Insomnia was significantly related to having mood disorders, anxiety disorders, substance use disorders and psychotic disorders. Insomnia was also more common among women, older adults, working participants and those who practice a religion. CONCLUSIONS The prevalence of insomnia was highly variable between sites, but the predictors appeared to be the same everywhere. Insomnia seemed to be more related to the presence of mood and anxiety disorders than a site-specific effect and thus may be a good indicator of mental health.
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11
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Malheiros LEA, Knebel MTG, Lopes MVV, Mello GTD, Barbosa Filho VC, Silva KSD. Adequate sleep duration among children and adolescents: a review of the Brazil's Report Card. REVISTA BRASILEIRA DE CINEANTROPOMETRIA E DESEMPENHO HUMANO 2021. [DOI: 10.1590/1980-0037.2021v23e82644] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
abstract – This study aimed to summarize existing research examining the prevalence of adequate sleep duration or meeting sleep recommendations among Brazilian children and adolescents. A systematic review was conducted on eight databases. The criteria for inclusion were original research, samples including Brazilian children and adolescents (age 0–18), studies that reported variables regarding sleep duration using both objective or subjective measures, school- or population-based surveys with random sampling, and cross-sectional or cohort studies. Of the 54 articles included, only 27 used data from different studies. Most of the studies were conducted in the southern region (n = 17) with only two studies having a nationally representative sample. Two studies included children below age five, and the age group most investigated was adolescents (>10 years old). A majority of the studies used a self-reported questionnaire and showed variability in the cutoff point applied for adequate sleep duration with the most reported being ≥8 hours. The proportion of adolescents who met recommendations or had adequate sleep duration ranged from 15% to 89%. Among children, the prevalence ranged from 17% to 95%. The least variability was observed among toddlers, ranging from 93% to 95%. No consistent gender differences were observed among the gender-stratified groups of children and adolescents across the studies. It can be observed that, because of the wide range of results and the lack of data with national representativeness, the prevalence of sufficient sleep among young people aged below 18 remains undefined in Brazil.
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12
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Deng Y, Wang G, Ye X, Jiang Y, Lin Q, Dong S, Song Y, Zhu L, Meng M, Li W, Zhu Q, Sun W, Jiang F. The association between 25-hydroxyvitamin D levels and children's sleep-wake patterns: a prospective cohort study. Sleep Med 2019; 67:207-214. [PMID: 31952028 DOI: 10.1016/j.sleep.2019.11.1252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 11/16/2019] [Accepted: 11/20/2019] [Indexed: 01/08/2023]
Abstract
OBJECTIVE To explore the association between vitamin D in cord blood or in venous blood and children's sleep-wake patterns at two years of age. METHODS Data were from 209 children in a birth cohort, Shanghai Sleep Birth Cohort Study (SSBC). 25-Hydroxyvitamin D (25(OH)D) was assessed in cord blood and venous blood samples at two years of age by electrochemiluminescence immunoassay. Children's sleep-wake patterns were measured with the Brief Infant Sleep Questionnaire (BISQ) and Acti-Watch at two years of age. RESULTS The prevalence of vitamin D deficiency (defined as <50 nmol/L) was 50.4% in cord blood and 28% at two years of age. The cord blood 25(OH)D level was not significantly associated with children's sleep at two years of age. Children with 25(OH)D deficiency at two years old had shorter reported and actigraphic night sleep duration (NSD) and total sleep duration (TSD) than those with normal 25(OH)D concentration. 25(OH)D level at two years old was positively associated with night and total sleep duration (βreported-NSD = 0.6, p = 0.011; βreported-TSD = 0.6, p = 0.029; βactigraphic-NSD = 0.82, p = 0.003; βactigraphic-TSD = 0.78, p = 0.006), but was not associated with daytime sleep duration. There was no significant association between 25(OH)D level with night waking duration and midpoint of sleep either measured subjectively or objectively. CONCLUSION We found that not cord blood 25(OH)D level but two-year-old 25(OH)D level was associated with children's sleep-wake patterns at two years of age. These findings suggest more attention should be paid to the assessment of 25(OH)D levels in children with short sleep duration.
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Affiliation(s)
- Yujiao Deng
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guanghai Wang
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xiuxia Ye
- Neonatal Intensive Care Unit, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yanrui Jiang
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qingmin Lin
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shumei Dong
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Yuanjin Song
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Lixia Zhu
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Min Meng
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wen Li
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Qi Zhu
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Wanqi Sun
- Department of Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fan Jiang
- Department of Developmental and Behavioral Pediatrics, Pediatric Translational Medicine Institution, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China; MOE and Shanghai Key Laboratory of Children's Environmental Health, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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Wendt A, da Silva ICM, Gonçalves H, Assunção MCF, Menezes AMB, Wehrmeister FC. Sleep parameters measured by accelerometry: descriptive analyses from the 22-year follow-up of the Pelotas 1993 birth cohort. Sleep Med 2019; 67:83-90. [PMID: 31918122 DOI: 10.1016/j.sleep.2019.10.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 04/10/2019] [Accepted: 10/17/2019] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To describe the sleep time window (STW), total sleep time (TST), and sleep percent [SP = (TST/STW) × 100] by accelerometry in a population-based young adult cohort in Brazil. METHODS Cross-sectional analysis with a 22-year sample (N = 2462). Sleep variables were measured using an accelerometer. The devices were worn on the non-dominant wrist for approximately seven days. A raw data analysis using the GGIR package was performed. The following sleep variables were extracted: TST, STW, and SP. Linear regression was used to adjust averages. All analyses were stratified according to sex. A comparison between weekday and weekend averages was also conducted. RESULTS The means of TST, STW, and SP for men were 5.9 h, 7.1 h, and 83.1%, respectively. For women, the means of TST, STW, and SP were 6.4 h, 7.6 h, and 84.6%, respectively. Women presented a higher means of all outcomes compared to men (p < 0.001). After adjusting for both sexes, white skin color and not working or studying were associated with higher TST. Individuals not working or studying presented higher means of STW and lower sleep SP. Women with children who were less than two years of age presented lower values of three evaluated outcomes. Regarding behavior and health condition variables, obesity was associated with lower STW only for men. Physical activity was associated with higher SP and risk drinking with lower TST and STW only for women. CONCLUSION Differences between sexes were observed in TST, STW, and SP. In all outcomes women presented a higher means. Socioeconomic variables were associated with both sexes, but having children and behavior/health conditions differed between sexes.
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Affiliation(s)
- Andrea Wendt
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
| | - Inácio Crochemore Mohnsan da Silva
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
| | - Helen Gonçalves
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
| | - Maria Cecilia F Assunção
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
| | - Ana Maria B Menezes
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
| | - Fernando C Wehrmeister
- Federal University of Pelotas, Post-graduate Program in Epidemiology, Marechal Deodoro, 1160 - 3rd Floor, CEP 96020-220, Pelotas, RS, Brazil.
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Kentiba E, George M, Mondal S, Mathi Vanan D. Effects of altitude on chronotype orientations in relation to cardiorespiratory and hematological quantities of college students in Ethiopia. PLoS One 2019; 14:e0219836. [PMID: 31314762 PMCID: PMC6636757 DOI: 10.1371/journal.pone.0219836] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 07/02/2019] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The mechanism by which Ethiopians adapt to altitude is quite unique compared to other Highlanders with respect to increased oxygen saturation of hemoglobin. Although the effects of altitude on cardiorespiratory and hematological quantities on athletics performances are well known, but there is little information about its underlying effect on chronotype orientations. METHODS In this cross-sectional study 60 male college students with mean age 20±1.3 years from high and low altitude regions living in a tropical setting in Ethiopia were included. The participants' chronotype was determined using the self-administered Horne and Ostberg Morningness-Eveningness Questionnaires (MEQ). Measurements and estimations of hematological and cardiorespiratory parameters were performed from 7:00-9:00 AM, East African time zone, in order to minimize any variations that might occur in the course of the day. A multivariate binary logistic regression model was fitted to analyze the underlying chronotype predictors. RESULTS 28 (93.9%) of participants from high altitude were mainly intermediate type (I-type) dominant with (MEQ = 42-58). While, 16 (55.2%) of participants from low altitudes were morning type (M-type) dominant chronotype with (MEQ = 59-69). Our main finding confirmed that altitude is an independent predictor of chronotype orientations of the participants (p<0.015). Thus, the results of the multivariate analysis seem to indicate that, participants from low and high altitudes may be uniquely oriented towards either M-type or I-type chronotype respectively (adjusted odds ratio [AOR] 4.772, 95% CI = 3.748-4618458). However, no significant difference on cardiorespiratory and hematological quantities between I-type and M-type chronotype of students from low altitude living in the same setting was reported (p > 0.05). CONCLUSION Our finding, reported for the first time that, the human chronotype varies according to the altitude, with no underlying effect of cardiorespiratory and hematological quantities.
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Affiliation(s)
- Efrem Kentiba
- Department of Sports Science, Arba Minch College of Teachers’ Education, Arba Minch, Ethiopia
- Department of Sports Science, Mekelle University College of Natural and Computational Sciences, Mekelle, Ethiopia
| | - Mala George
- Department of Biochemistry, School of Medicine, Division of Biomedical Sciences, Mekelle University, Mekelle, Ethiopia
| | - Soumitra Mondal
- Department of Sports Science, Mekelle University College of Natural and Computational Sciences, Mekelle, Ethiopia
| | - D. Mathi Vanan
- Department of Sports Science, Mekelle University College of Natural and Computational Sciences, Mekelle, Ethiopia
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15
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Schokman A, Bin YS, Simonelli G, Pye J, Morris R, Sumathipala A, Siribaddana SH, Hotopf M, Rijsdijk F, Jayaweera K, Glozier N. Agreement between subjective and objective measures of sleep duration in a low-middle income country setting. Sleep Health 2018; 4:543-550. [DOI: 10.1016/j.sleh.2018.08.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 08/24/2018] [Accepted: 08/30/2018] [Indexed: 01/01/2023]
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16
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Jia JL, Chen S, Sivarajah V, Stephens D, Cortez MA. Latitudinal differences on the global epidemiology of infantile spasms: systematic review and meta-analysis. Orphanet J Rare Dis 2018; 13:216. [PMID: 30486850 PMCID: PMC6262963 DOI: 10.1186/s13023-018-0952-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 11/14/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Infantile spasms represent the catastrophic, age-specific seizure type associated with acute and long-term neurological morbidity. However, due to rarity and heterogenous determination, there is persistent uncertainty of its pathophysiological and epidemiological characteristics. The purpose of the current study was to address a historically suspected latitudinal basis of infantile spasms incidence, and to interrogate a geographical basis of epidemiology, including the roles of latitude and other environmental factors, using meta-analytic and -regression methods. METHODS A systematic search was performed in Ovid MEDLINE and Embase for primary reports on infantile spasms incidence and prevalence epidemiology. RESULTS One thousand fifteen studies were screened to yield 54 eligible publications, from which 39 incidence figures and 18 prevalence figures were extracted. The pooled incidence was 0.249 cases/1000 live births. The pooled prevalence was 0.015 cases/1000 population. Univariate meta-regression determined a continental effect, with Europe demonstrating the highest onset compared from Asia (OR = 0.51, p = 0.004) and from North America (OR = 0.50, p = 0.004). Latitude was also positively correlated with incidence globally (OR = 1.02, p < 0.001). Sub-analyses determined a particularly elevated Scandinavian incidence compared to the rest of world (OR = 1.88, p < 0.001), and lack of latitudinal effect with Scandinavian exclusion (p = 0.10). Metrics of healthcare quality did not predict incidence. Multiple meta-regression determined that latitude was the key predictor of incidence (OR = 1.02, p = 0.001). CONCLUSIONS This is the first systematic epidemiological study of infantile spasms. Limitations included lack of Southern hemispheric representation, insufficient study selection and size to support some sub-continental analyses, and lack of accessible ethnic and healthcare quality data. Meta-analyses determined a novel, true geographical difference in incidence which is consistent with a latitudinal and/or ethnic contribution to epileptogenesis. These findings justify the establishment of a global registry of infantile spasms epidemiology to promote future systematic studies, clarify risk factors, and expand understanding of the pathophysiology.
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Affiliation(s)
- Jason L. Jia
- Department of Medicine, University of Toronto, 190 Elizabeth Street R. Fraser Elliott Wing, Toronto, M5G 2C4 Canada
| | - Shiyi Chen
- Child Health Evaluative Sciences Research Program, SickKids Research Institute, The Hospital for Sick Children, Toronto, Canada
| | - Vishalini Sivarajah
- Department of Medicine, University of Toronto, 190 Elizabeth Street R. Fraser Elliott Wing, Toronto, M5G 2C4 Canada
| | - Derek Stephens
- Child Health Evaluative Sciences Research Program, SickKids Research Institute, The Hospital for Sick Children, Toronto, Canada
| | - Miguel A. Cortez
- Department of Pediatrics, Division of Neurology, University of Toronto, Toronto, Canada
- Neurosciences & Mental Health Program, Peter Gilgan Centre for Research and Learning, SickKids Research Institute, The Hospital for Sick Children, 555 University Avenue, Toronto, ON M5G 1X8 Canada
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17
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Gu F, Xu S, Devesa SS, Zhang F, Klerman EB, Graubard BI, Caporaso NE. Longitude Position in a Time Zone and Cancer Risk in the United States. Cancer Epidemiol Biomarkers Prev 2017; 26:1306-1311. [PMID: 28450580 DOI: 10.1158/1055-9965.epi-16-1029] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/20/2017] [Accepted: 04/06/2017] [Indexed: 12/26/2022] Open
Abstract
Background: Circadian disruption is a probable human carcinogen. From the eastern to western border of a time zone, social time is equal, whereas solar time is progressively delayed, producing increased discrepancies between individuals' social and biological circadian time. Accordingly, western time zone residents experience greater circadian disruption and may be at an increased risk of cancer.Methods: We examined associations between the position in a time zone and age-standardized county-level incidence rates for total cancers combined and 23 specific cancers by gender using the data of the Surveillance, Epidemiology, and End Results Program (2000-2012), including four million cancer diagnoses in white residents of 607 counties in 11 U.S. states. Log-linear regression was conducted, adjusting for latitude, poverty, cigarette smoking, and state. Bonferroni-corrected P values were used as the significance criteria.Results: Risk increased from east to west within a time zone for total and for many specific cancers, including chronic lymphocytic leukemia (both genders) and cancers of the stomach, liver, prostate, and non-Hodgkin lymphoma in men and cancers of the esophagus, colorectum, lung, breast, and corpus uteri in women.Conclusions: Risk increased from the east to the west in a time zone for total and many specific cancers, in accord with the circadian disruption hypothesis. Replications in analytic epidemiologic studies are warranted.Impact: Our findings suggest that circadian disruption may not be a rare phenomenon affecting only shift workers, but is widespread in the general population with broader implications for public health than generally appreciated. Cancer Epidemiol Biomarkers Prev; 26(8); 1306-11. ©2017 AACR.
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Affiliation(s)
- Fangyi Gu
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.,Roswell Park Cancer Institute, Buffalo, New York
| | - Shangda Xu
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.,Harvard University, Cambridge, Massachusetts
| | - Susan S Devesa
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland
| | - Fanni Zhang
- Information Management Services, Inc., Rockville, Maryland
| | - Elizabeth B Klerman
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts
| | - Barry I Graubard
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland
| | - Neil E Caporaso
- Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland.
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