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Mortlock E, Silovský V, Güldenpfennig J, Faltusová M, Olejarz A, Börger L, Ježek M, Jennings DJ, Capellini I. Sleep in the wild: the importance of individual effects and environmental conditions on sleep behaviour in wild boar. Proc Biol Sci 2024; 291:20232115. [PMID: 38808449 DOI: 10.1098/rspb.2023.2115] [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: 09/16/2023] [Accepted: 04/19/2024] [Indexed: 05/30/2024] Open
Abstract
Sleep serves vital physiological functions, yet how sleep in wild animals is influenced by environmental conditions is poorly understood. Here we use high-resolution biologgers to investigate sleep in wild animals over ecologically relevant time scales and quantify variability between individuals under changing conditions. We developed a robust classification for accelerometer data and measured multiple dimensions of sleep in the wild boar (Sus scrofa) over an annual cycle. In support of the hypothesis that environmental conditions determine thermoregulatory challenges, which regulate sleep, we show that sleep quantity, efficiency and quality are reduced on warmer days, sleep is less fragmented in longer and more humid days, while greater snow cover and rainfall promote sleep quality. Importantly, this longest and most detailed analysis of sleep in wild animals to date reveals large inter- and intra-individual variation. Specifically, short-sleepers sleep up to 46% less than long-sleepers but do not compensate for their short sleep through greater plasticity or quality, suggesting they may pay higher costs of sleep deprivation. Given the major role of sleep in health, our results suggest that global warming and the associated increase in extreme climatic events are likely to negatively impact sleep, and consequently health, in wildlife, particularly in nocturnal animals.
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Affiliation(s)
- Euan Mortlock
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
| | - Václav Silovský
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol 165 00, Czech Republic
| | - Justine Güldenpfennig
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol 165 00, Czech Republic
| | - Monika Faltusová
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol 165 00, Czech Republic
| | - Astrid Olejarz
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol 165 00, Czech Republic
| | - Luca Börger
- Department of Biosciences, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Miloš Ježek
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol 165 00, Czech Republic
| | - Dómhnall J Jennings
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
| | - Isabella Capellini
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, UK
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2
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Olejarz A, Faltusová M, Börger L, Güldenpfennig J, Jarský V, Ježek M, Mortlock E, Silovský V, Podgórski T. Worse sleep and increased energy expenditure yet no movement changes in sub-urban wild boar experiencing an influx of human visitors (anthropulse) during the COVID-19 pandemic. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 879:163106. [PMID: 36966827 PMCID: PMC10038670 DOI: 10.1016/j.scitotenv.2023.163106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/14/2023] [Accepted: 03/23/2023] [Indexed: 05/17/2023]
Abstract
Expansion of urban areas, landscape transformation and increasing human outdoor activities strongly affect wildlife behaviour. The outbreak of the COVID-19 pandemic in particular led to drastic changes in human behaviour, exposing wildlife around the world to either reduced or increased human presence, potentially altering animal behaviour. Here, we investigate behavioural responses of wild boar (Sus scrofa) to changing numbers of human visitors to a suburban forest near Prague, Czech Republic, during the first 2.5 years of the COVID-19 epidemic (April 2019-November 2021). We used bio-logging and movement data of 63 GPS-collared wild boar and human visitation data based on an automatic counter installed in the field. We hypothesised that higher levels of human leisure activity will have a disturbing effect on wild boar behaviour manifested in increased movements and ranging, energy spent, and disrupted sleep patterns. Interestingly, whilst the number of people visiting the forest varied by two orders of magnitude (from 36 to 3431 people weekly), even high levels of human presence (>2000 visitors per week) did not affect weekly distance travelled, home range size, and maximum displacement of wild boar. Instead, individuals spent 41 % more energy at high levels of human presence (>2000 visitors per week), with more erratic sleep patterns, characterised by shorter and more frequent sleeping bouts. Our results highlight multifaceted effects of increased human activities ('anthropulses'), such as those related to COVID-19 countermeasures, on animal behaviour. High human pressure may not affect animal movements or habitat use, especially in highly adaptable species such as wild boar, but may disrupt animal activity rhythms, with potentially detrimental fitness consequences. Such subtle behavioural responses can be overlooked if using only standard tracking technology.
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Affiliation(s)
- Astrid Olejarz
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic.
| | - Monika Faltusová
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic
| | - Luca Börger
- Department of Biosciences, Swansea University, Singleton Park, Swansea SA2 8PP, Wales, UK
| | - Justine Güldenpfennig
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic
| | - Vilém Jarský
- Department of Forestry and Wood Economics, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic
| | - Miloš Ježek
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic
| | - Euan Mortlock
- School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT95DL, Northern Ireland, UK
| | - Václav Silovský
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic
| | - Tomasz Podgórski
- Department of Game Management and Wildlife Biology, Faculty of Forestry and Wood Sciences,Czech University of Life Sciences, Kamýcká 129, Prague 6-Suchdol, 165 00, Czech Republic; Mammal Research Institute, Polish Academy of Sciences, Stoczek 1, 17-230 Białowieża, Poland
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3
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Gavrilov VM, Golubeva TB, Bushuev AV. Metabolic rate, sleep duration, and body temperature in evolution of mammals and birds: the influence of geological time of principal groups divergence. Zookeys 2023; 1148:1-27. [DOI: 10.3897/zookeys.1148.93458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Accepted: 01/11/2023] [Indexed: 02/16/2023] Open
Abstract
This study contains an analysis of basal metabolic rate (BMR) in 1817 endothermic species. The aim was to establish how metabolic scaling varies between the main groups of endotherms during evolution. The data for all the considered groups were combined and the common exponent in the allometric relationship between the BMR and body weight was established as b = 0.7248. Reduced to the common slope, the relative metabolic rate forms the following series: Neognathae – Passeriformes – 1.00, Neognathae – Non-Passeriformes – 0.75, Palaeognathae – 0.53, Eutheria – 0.57, Marsupialia – 0.44, and Monotremata – 0.26. The main finding is that the metabolic rate in the six main groups of mammals and birds consistently increases as the geological time of the group’s divergence approaches the present. In parallel, the average body temperature in the group rises, the duration of sleep decreases and the duration of activity increases. BMR in a taxon correlates with its evolutionary age: the later a clade diverged, the higher is its metabolic rate and the longer is its activity period; group exponents decrease as group divergence nears present times while with increase metabolic rate during activity, they not only do not decrease but can increase. Sleep duration in mammals was on average 40% longer than in birds while BMR, in contrast, was 40% higher in birds. The evolution of metabolic scaling, body temperature, sleep duration, and activity during the development of endothermic life forms is demonstrated, allowing for a better understanding of the underlying principles of endothermy formation.
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Shukla I, Kilpatrick AM, Beltran RS. Variation in resting strategies across trophic levels and habitats in mammals. Ecol Evol 2021; 11:14405-14415. [PMID: 34765115 PMCID: PMC8571619 DOI: 10.1002/ece3.8073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/26/2021] [Accepted: 08/18/2021] [Indexed: 12/30/2022] Open
Abstract
Mammals must carefully balance rest with other behaviors that influence fitness (e.g., foraging, finding a mate) while minimizing predation risk. However, factors influencing resting strategies and the degree to which resting strategies are driven by the activities of predators and/or prey remain largely unknown. Our goal was to examine how mammalian resting strategies varied with trophic level, body mass, and habitat. We reviewed findings from 127 publications and classified the resting strategies of terrestrial and aquatic mammalian species into three categories: social (e.g., resting in groups), temporal (e.g., resting during the day), or spatial (e.g., resting in burrows). Temporal strategies were most common (54% of cases), but the prevalence of strategies varied with body mass and among trophic levels. Specifically, lower trophic levels and smaller species such as rodents and lagomorphs used more spatial and social resting strategies, whereas top predators and larger species used mostly temporal resting strategies. Resting strategies also varied among habitat types (e.g., rainforest vs. grassland), but this was primarily because closely related species shared both habitats and resting strategies. Human presence also affected resting strategies at all trophic levels but most strongly influenced top predators through shifts in rest timing. Human-induced behavioral changes in rest patterns cascade to modify behaviors across multiple trophic levels. These findings advance our fundamental understanding of natural history and ecology in wild animals and provide a roadmap for future comparative studies.
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Affiliation(s)
- Ishana Shukla
- Ecology and Evolutionary BiologyUniversity of CaliforniaSanta CruzCAUSA
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Mohanty NP, Wagener C, Herrel A, Thaker M. The ecology of sleep in non-avian reptiles. Biol Rev Camb Philos Soc 2021; 97:505-526. [PMID: 34708504 DOI: 10.1111/brv.12808] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 10/10/2021] [Accepted: 10/18/2021] [Indexed: 01/10/2023]
Abstract
Sleep is ubiquitous in the animal kingdom and yet displays considerable variation in its extent and form in the wild. Ecological factors, such as predation, competition, and microclimate, therefore are likely to play a strong role in shaping characteristics of sleep. Despite the potential for ecological factors to influence various aspects of sleep, the ecological context of sleep in non-avian reptiles remains understudied and without systematic direction. In this review, we examine multiple aspects of reptilian sleep, including (i) habitat selection (sleep sites and their spatio-temporal distribution), (ii) individual-level traits, such as behaviour (sleep postures), morphology (limb morphometrics and body colour), and physiology (sleep architecture), as well as (iii) inter-individual interactions (intra- and inter-specific). Throughout, we discuss the evidence of predation, competition, and thermoregulation in influencing sleep traits and the possible evolutionary consequences of these sleep traits for reptile sociality, morphological specialisation, and habitat partitioning. We also review the ways in which sleep ecology interacts with urbanisation, biological invasions, and climate change. Overall, we not only provide a systematic evaluation of the conceptual and taxonomic biases in the existing literature on reptilian sleep, but also use this opportunity to organise the various ecological hypotheses for sleep characteristics. By highlighting the gaps and providing a prospectus of research directions, our review sets the stage for understanding sleep ecology in the natural world.
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Affiliation(s)
- Nitya P Mohanty
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
| | - Carla Wagener
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, Stellenbosch, Western Cape, 7600, South Africa
| | - Anthony Herrel
- Département Adaptations du Vivant, MECADEV UMR7179 CNRS/MNHN, Paris, France
| | - Maria Thaker
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560 012, India
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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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Weaver MD, Sletten TL, Foster RG, Gozal D, Klerman EB, Rajaratnam SMW, Roenneberg T, Takahashi JS, Turek FW, Vitiello MV, Young MW, Czeisler CA. Adverse impact of polyphasic sleep patterns in humans: Report of the National Sleep Foundation sleep timing and variability consensus panel. Sleep Health 2021; 7:293-302. [PMID: 33795195 DOI: 10.1016/j.sleh.2021.02.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 01/02/2023]
Abstract
Polyphasic sleep is the practice of distributing multiple short sleep episodes across the 24-hour day rather than having one major and possibly a minor ("nap") sleep episode each day. While the prevalence of polyphasic sleep is unknown, anecdotal reports suggest attempts to follow this practice are common, particularly among young adults. Polyphasic-sleep advocates claim to thrive on as little as 2 hours of total sleep per day. However, significant concerns have been raised that polyphasic sleep schedules can result in health and safety consequences. We reviewed the literature to identify the impact of polyphasic sleep schedules (excluding nap or siesta schedules) on health, safety, and performance outcomes. Of 40,672 potentially relevant publications, with 2,023 selected for full-text review, 22 relevant papers were retained. We found no evidence supporting benefits from following polyphasic sleep schedules. Based on the current evidence, the consensus opinion is that polyphasic sleep schedules, and the sleep deficiency inherent in those schedules, are associated with a variety of adverse physical health, mental health, and performance outcomes. Striving to adopt a schedule that significantly reduces the amount of sleep per 24 hours and/or fragments sleep into multiple episodes throughout the 24-hour day is not recommended.
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Affiliation(s)
- Matthew D Weaver
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Tracey L Sletten
- Turner Institute for Brain and Mental Health and School of Psychological Sciences, Monash University, Clayton, Australia
| | - Russell G Foster
- Sleep & Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - David Gozal
- Department of Child Health, University of Missouri, Columbia, Missouri, USA
| | - Elizabeth B Klerman
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, USA; Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Shantha M W Rajaratnam
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, USA; Turner Institute for Brain and Mental Health and School of Psychological Sciences, Monash University, Clayton, Australia
| | - Till Roenneberg
- Institute for Medical Psychology, Ludwig Maximilian University of Munich, Munich, Germany
| | - Joseph S Takahashi
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, Texas, USA; Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Fred W Turek
- Center for Sleep and Circadian Biology, Department of Neurobiology, Northwestern University, Evanston, Illinois, USA
| | - Michael V Vitiello
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA
| | - Michael W Young
- Laboratory of Genetics, The Rockefeller University, New York, New York, USA
| | - Charles A Czeisler
- Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, Massachusetts, USA; Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, USA.
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8
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Burger AL, Hartig J, Dierkes PW. Biological and environmental factors as sources of variation in nocturnal behavior of giraffe. Zoo Biol 2021; 40:171-181. [PMID: 33666286 DOI: 10.1002/zoo.21596] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/09/2021] [Indexed: 01/01/2023]
Abstract
Upon a drastic decline of the giraffe population in the wild, conservation efforts and therefore the role of zoos have become more important than ever. With their unique opportunities, zoos provide excellent conditions to study animal behavior, expanding the knowledge about the giraffe's behavior repertoire and their ability to adapt. This study therefore examined the nocturnal behavior of 63 giraffe living in 13 different EAZA zoos across Germany and the Netherlands. Giraffe were observed and videos recorded via infrared sensitive cameras during the winter seasons 2015-2018. The observation period spanned nightly from 17:00 to 7:00. Thus, 198 nights, with a total of 2772 h were recorded and analyzed. Linear mixed models were then used to assess potential biological and environmental factors influencing behavior during the dark phase. Results show that individual variables such as age, subspecies and motherhood determined nocturnal activity and sleep behavior most. Among the variables studied, husbandry conditions and environmental factors complying with EAZA standards had no influence on the giraffe's nocturnal behavior. By combining nocturnal activity analyses and an assessment of potential influencing factors, our findings present a holistic approach to a better understanding of captive giraffe behavior and allow for management implications.
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Affiliation(s)
- Anna Lena Burger
- Bioscience Education and Zoo Biology, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Johannes Hartig
- Department of Educational Quality and Evaluation, DIPF, Leibniz Institute for Research and Information in Education, Frankfurt am Main, Germany
| | - Paul W Dierkes
- Bioscience Education and Zoo Biology, Goethe University Frankfurt, Frankfurt am Main, Germany
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9
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Alimenti K, Chen A, Saxena R, Dashti HS. Habitual Sleep Duration, Daytime Napping, and Dietary Intake: A Mendelian Randomization Study. Curr Dev Nutr 2021; 5:nzab019. [PMID: 34095735 PMCID: PMC8171253 DOI: 10.1093/cdn/nzab019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 02/12/2021] [Accepted: 02/23/2021] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Chronic inadequate sleep and frequent daytime napping may inflict deleterious health effects including weight gain, cardiometabolic and psychiatric diseases, and cancer. It is plausible that these relations may be partly influenced by the consumption of suboptimal diets. OBJECTIVES The study aimed to identify potential causal links of genetically proxied longer habitual sleep duration and more frequent daytime napping on 61 dietary variables derived from an FFQ. In addition, the study aimed to assess potential bidirectional causal links between habitual sleep duration or daytime napping and macronutrient composition. METHODS Genetic variants robustly associated with habitual sleep duration and daytime napping from published genome-wide association analyses were used. Outcomes included 61 dietary variables estimated from FFQs in the UK Biobank (n = 361,194). For bidirectional associations with macronutrient composition, genetic variants associated with percentage of energy from carbohydrate, fat, and protein were used. Two-sample Mendelian randomization (MR) effects were estimated with inverse-variance weighted (IVW) analysis. RESULTS In 2-sample MR, genetically proxied longer sleep duration was associated with a 0.068 (95% CI: 0.034, 0.103) category increase in salad/raw vegetable intake [P false discovery rate (FDR) = 0.006] per hour of sleep and with "no major dietary changes in the past 5 years" (P FDR = 0.043). No associations were evident for daytime napping on dietary variables (all P FDR > 0.05). In addition, there were no bidirectional associations between habitual sleep duration or daytime napping with the relative intake of carbohydrate, fat, and protein (all P IVW > 0.05). CONCLUSIONS In this MR study, there was modest evidence for associations between habitual sleep duration with dietary intake and no evidence for associations between daytime napping frequency with dietary intake. These preliminary findings suggest that changes to habitual sleep duration or daytime napping frequency may have limited impact on long-term changes in dietary intake.
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Affiliation(s)
- Kaitlyn Alimenti
- Center for Genomic Medicine, Massachusetts General Hospital,
Boston, MA, USA
| | - Angela Chen
- Center for Genomic Medicine, Massachusetts General Hospital,
Boston, MA, USA
| | - Richa Saxena
- Center for Genomic Medicine, Massachusetts General Hospital,
Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts
General Hospital and Harvard Medical School, Boston, MA, USA
- Division of Sleep Medicine, Harvard Medical School, Boston,
MA, USA
| | - Hassan S Dashti
- Center for Genomic Medicine, Massachusetts General Hospital,
Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts
General Hospital and Harvard Medical School, Boston, MA, USA
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10
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Sleep in two free-roaming blue wildebeest ( Connochaetes taurinus), with observations on the agreement of polysomnographic and actigraphic techniques. IBRO Neurosci Rep 2021; 10:142-152. [PMID: 34179868 PMCID: PMC8211919 DOI: 10.1016/j.ibneur.2021.02.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 02/09/2021] [Indexed: 12/28/2022] Open
Abstract
Most studies examining sleep in mammals are done under controlled conditions in laboratory/zoological facilities with few studies being conducted in their natural environment. It is not always possible to record sleep polysomnographically (PSG) from animals in their natural environments, as PSG is invasive, requiring the surgical implantation of electrodes on the surface of the brain. In contrast, actigraphy (ACT) has been shown to be a minimally-invasive method to objectively measure overall sleep times in some mammals, although not revealing specific sleep states. The aim of this study is two-fold, first, to measure sleep polysomnographically in free-roaming blue wildebeest (Connochaetes taurinus) under the most natural conditions possible, and second, to establish the degree of concordance between ACT and PSG recordings undertaken simultaneously in the same individuals. Here we examined sleep in the blue wildebeest, in a naturalistic setting, using both polysomnography (PSG) and actigraphy (ACT). PSG showed that total sleep time (TST) in the blue wildebeest for a 24-h period was 4.53 h (±0.12 h), 4.26 h (±0.11 h) spent in slow wave (non-REM) sleep and 0.28 h (±0.01 h) spent in rapid eye movement (REM) sleep, with 19.47 h (±0.12 h) spent in Wake. ACT showed that the blue wildebeest spent 19.23 h (±0.18 h) Active and 4.77 h (±0.18 h) Inactive. For both animals studied, a fair agreement between the two techniques for sleep scoring was observed, with approximately 45% of corresponding epochs analyzed being scored as both sleep (using PSG) and inactive (using ACT).
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11
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Dashti HS, Daghlas I, Lane JM, Huang Y, Udler MS, Wang H, Ollila HM, Jones SE, Kim J, Wood AR, Weedon MN, Aslibekyan S, Garaulet M, Saxena R. Genetic determinants of daytime napping and effects on cardiometabolic health. Nat Commun 2021; 12:900. [PMID: 33568662 PMCID: PMC7876146 DOI: 10.1038/s41467-020-20585-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
Daytime napping is a common, heritable behavior, but its genetic basis and causal relationship with cardiometabolic health remain unclear. Here, we perform a genome-wide association study of self-reported daytime napping in the UK Biobank (n = 452,633) and identify 123 loci of which 61 replicate in the 23andMe research cohort (n = 541,333). Findings include missense variants in established drug targets for sleep disorders (HCRTR1, HCRTR2), genes with roles in arousal (TRPC6, PNOC), and genes suggesting an obesity-hypersomnolence pathway (PNOC, PATJ). Association signals are concordant with accelerometer-measured daytime inactivity duration and 33 loci colocalize with loci for other sleep phenotypes. Cluster analysis identifies three distinct clusters of nap-promoting mechanisms with heterogeneous associations with cardiometabolic outcomes. Mendelian randomization shows potential causal links between more frequent daytime napping and higher blood pressure and waist circumference.
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Affiliation(s)
- Hassan S Dashti
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Iyas Daghlas
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
| | - Jacqueline M Lane
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | | | - Miriam S Udler
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Diabetes Unit, Massachusetts General Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
| | - Heming Wang
- Broad Institute, Cambridge, MA, USA
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Hanna M Ollila
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Broad Institute, Cambridge, MA, USA
- Institute for Molecular Medicine FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA, USA
| | - Samuel E Jones
- Institute for Molecular Medicine FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, UK
| | | | - Andrew R Wood
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, UK
| | - Michael N Weedon
- Genetics of Complex Traits, University of Exeter Medical School, Exeter, UK
| | | | - Marta Garaulet
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
- Department of Physiology, University of Murcia, Murcia, Spain.
- IMIB-Arrixaca, Murcia, Spain.
| | - Richa Saxena
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
- Broad Institute, Cambridge, MA, USA.
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA.
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12
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Cassidy LC, Hannibal DL, Semple S, McCowan B. Improved behavioral indices of welfare in continuous compared to intermittent pair-housing in adult female rhesus macaques (Macaca mulatta). Am J Primatol 2020; 82:e23189. [PMID: 32890432 PMCID: PMC7944647 DOI: 10.1002/ajp.23189] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 07/29/2020] [Accepted: 08/18/2020] [Indexed: 12/19/2022]
Abstract
Limiting opportunities for captive nonhuman primates (NHPs) to express species-specific social behaviors may disrupt the adaptive drive for social companionship and may lead to increases in coping behaviors and inactivity. While captive NHPs show improved welfare when moving to pair-housing from single-housing, the impact of daily separation of pair-mates, as is implemented in intermittent pair-housing, is not fully understood. We compared behavioral indices of welfare exhibited by adult female rhesus macaques (Macaca mulatta) in two conditions: (1) intermittent pair-housing, involving daily overnight separation of pair-mates, and (2) continuous pair-housing, involving little separation of pair-mates. A within-subjects study design tested two groups of females experiencing both pairing conditions in an alternate order, switching either from continuous to intermittent pair-housing, or from intermittent to continuous pair-housing. Behavioral observations, recording activity state, self-directed, abnormal, and social behaviors, were conducted at midday when all females were paired, and in the afternoon when intermittent pairs were separated. Females exhibited higher levels of inactivity and self-directed behavior when separated due to intermittent pair-housing in comparison to continuous pair-housing. In addition, intermittently paired females showed higher levels of grooming and other types of affiliation when paired, than during the same time frame when they were continuously paired. These results suggest that females in the continuous presence of a social partner experience improved levels of activity and do not need to elevate levels of behavioral coping mechanisms (e.g., self-scratching, increased affiliation) as they receive the benefits associated with social companionship consistently throughout the day. Overall, this study provides the first evidence that continuous pair-housing affords better welfare than intermittent pair-housing in adult female rhesus macaques. Pair-housing options, such as continuous pairing, that reduce reliance on behavioral coping mechanisms and promote adaptive social behavior throughout the entirety of the day should be prioritized over husbandry care scheduled for convenience.
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Affiliation(s)
- Lauren C. Cassidy
- Welfare and Cognition Group, Cognitive Neuroscience Laboratory, German Primate Center–Leibniz Institute for Primate Research, Goettingen, Germany
- Leibniz-ScienceCampus Primate Cognition, German Primate Center & University of Goettingen, Goettingen, Germany
| | - Darcy L. Hannibal
- California National Primate Research Center, University of California Davis, Davis, California
- Department of Population Health & Reproduction, University of California Davis, Davis, California
| | - Stuart Semple
- Centre for Research in Evolutionary, Social and Interdisciplinary Anthropology, University of Roehampton, London, United Kingdom
| | - Brenda McCowan
- California National Primate Research Center, University of California Davis, Davis, California
- Department of Population Health & Reproduction, University of California Davis, Davis, California
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13
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Jaggard JB, Lloyd E, Yuiska A, Patch A, Fily Y, Kowalko JE, Appelbaum L, Duboue ER, Keene AC. Cavefish brain atlases reveal functional and anatomical convergence across independently evolved populations. SCIENCE ADVANCES 2020; 6:eaba3126. [PMID: 32938683 PMCID: PMC7494351 DOI: 10.1126/sciadv.aba3126] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 07/31/2020] [Indexed: 05/06/2023]
Abstract
Environmental perturbation can drive behavioral evolution and associated changes in brain structure and function. The Mexican fish species, Astyanax mexicanus, includes eyed river-dwelling surface populations and multiple independently evolved populations of blind cavefish. We used whole-brain imaging and neuronal mapping of 684 larval fish to generate neuroanatomical atlases of surface fish and three different cave populations. Analyses of brain region volume and neural circuits associated with cavefish behavior identified evolutionary convergence in hindbrain and hypothalamic expansion, and changes in neurotransmitter systems, including increased numbers of catecholamine and hypocretin/orexin neurons. To define evolutionary changes in brain function, we performed whole-brain activity mapping associated with behavior. Hunting behavior evoked activity in sensory processing centers, while sleep-associated activity differed in the rostral zone of the hypothalamus and tegmentum. These atlases represent a comparative brain-wide study of intraspecies variation in vertebrates and provide a resource for studying the neural basis of behavioral evolution.
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Affiliation(s)
- James B Jaggard
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Evan Lloyd
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Anders Yuiska
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Adam Patch
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Yaouen Fily
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Johanna E Kowalko
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Lior Appelbaum
- The Faculty of Life Sciences and The Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Erik R Duboue
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
| | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL 33458, USA.
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14
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Snell-Rood E, Snell-Rood C. The developmental support hypothesis: adaptive plasticity in neural development in response to cues of social support. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190491. [PMID: 32475336 PMCID: PMC7293157 DOI: 10.1098/rstb.2019.0491] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2020] [Indexed: 12/13/2022] Open
Abstract
Across mammals, cues of developmental support, such as touching, licking or attentiveness, stimulate neural development, behavioural exploration and even overall body growth. Why should such fitness-related traits be so sensitive to developmental conditions? Here, we review what we term the 'developmental support hypothesis', a potential adaptive explanation of this plasticity. Neural development can be a costly process, in terms of time, energy and exposure. However, environmental variability may sometimes compromise parental care during this costly developmental period. We propose this environmental variation has led to the evolution of adaptive plasticity of neural and behavioural development in response to cues of developmental support, where neural development is stimulated in conditions that support associated costs. When parental care is compromised, offspring grow less and adopt a more resilient and stress-responsive strategy, improving their chances of survival in difficult conditions, similar to existing ideas on the adaptive value of early-life programming of stress. The developmental support hypothesis suggests new research directions, such as testing the adaptive value of reduced neural growth and metabolism in stressful conditions, and expanding the range of potential cues animals may attend to as indicators of developmental support. Considering evolutionary and ecologically appropriate cues of social support also has implications for promoting healthy neural development in humans. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.
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Affiliation(s)
- Emilie Snell-Rood
- Department of Ecology, Evolution and Behavior, University of Minnesota, 1479 Gortner Avenue, Gortner 140, St Paul, MN 55108, USA
| | - Claire Snell-Rood
- School of Public Health, University of California, Berkeley, Berkeley, CA, USA
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15
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Cid B, Carbone C, Fernandez FAS, Jansen PA, Rowcliffe JM, O'Brien T, Akampurira E, Bitariho R, Espinosa S, Gajapersad K, Santos TMR, Gonçalves ALS, Kinnaird MF, Lima MGM, Martin E, Mugerwa B, Rovero F, Salvador J, Santos F, Spironello WR, Wijntuin S, Oliveira‐Santos LGR. On the scaling of activity in tropical forest mammals. OIKOS 2020. [DOI: 10.1111/oik.07022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Bruno Cid
- Univ. Federal do Rio de Janeiro Rio de Janeiro Brazil
| | | | | | - Patrick A. Jansen
- Smithsonian Tropical Res. Inst. Balboa Ancon Ciudad de Panamá Panama
- Wageningen Univ. Wageningen the Netherlands
| | | | | | | | | | - Santiago Espinosa
- Pontificia Univ. Católica del Ecuador Vicente Ramón Roca Quito Equador
- Univ. Autónoma de San Luis Potosí San Luis de Potosí Mexico
| | | | - Thiago M. R. Santos
- Univ. Federal do Mato Grosso do Sul, Cidade Universitária Av. Costa e Silva – Pioneiros Mato Grosso do Sul Brazil
| | | | | | | | | | - Badru Mugerwa
- Inst. of Tropical Forest Conservation Mbarara Uganda
| | - Francesco Rovero
- Dept of Biology, Univ. of Florence Sesto Fiorentino Italy
- MUSE – Museo delle Scienze Trento Italy
| | - Julia Salvador
- Wildlife Conservation Society New York NY USA
- Pontificia Univ. Católica del Ecuador Vicente Ramón Roca Quito Equador
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16
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Kowalko J. Utilizing the blind cavefish Astyanax mexicanus to understand the genetic basis of behavioral evolution. J Exp Biol 2020; 223:223/Suppl_1/jeb208835. [DOI: 10.1242/jeb.208835] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
ABSTRACT
Colonization of novel habitats often results in the evolution of diverse behaviors. Comparisons between individuals from closely related populations that have evolved divergent behaviors in different environments can be used to investigate behavioral evolution. However, until recently, functionally connecting genotypes to behavioral phenotypes in these evolutionarily relevant organisms has been difficult. The development of gene editing tools will facilitate functional genetic analysis of genotype–phenotype connections in virtually any organism, and has the potential to significantly transform the field of behavioral genetics when applied to ecologically and evolutionarily relevant organisms. The blind cavefish Astyanax mexicanus provides a remarkable example of evolution associated with colonization of a novel habitat. These fish consist of a single species that includes sighted surface fish that inhabit the rivers of Mexico and southern Texas and at least 29 populations of blind cavefish from the Sierra Del Abra and Sierra de Guatemala regions of Northeast Mexico. Although eye loss and albinism have been studied extensively in A. mexicanus, derived behavioral traits including sleep loss, alterations in foraging and reduction in social behaviors are now also being investigated in this species to understand the genetic and neural basis of behavioral evolution. Astyanax mexicanus has emerged as a powerful model system for genotype–phenotype mapping because surface and cavefish are interfertile. Further, the molecular basis of repeated trait evolution can be examined in this species, as multiple cave populations have independently evolved the same traits. A sequenced genome and the implementation of gene editing in A. mexicanus provides a platform for gene discovery and identification of the contributions of naturally occurring variation to behaviors. This review describes the current knowledge of behavioral evolution in A. mexicanus with an emphasis on the molecular and genetic underpinnings of evolved behaviors. Multiple avenues of new research that can be pursued using gene editing tools are identified, and how these will enhance our understanding of behavioral evolution is discussed.
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Affiliation(s)
- Johanna Kowalko
- Harriet L. Wilkes Honors College, Florida Atlantic University, Jupiter, FL 33458, USA
- Program of Neurogenetics, Florida Atlantic University, Jupiter, FL 33458, USA
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17
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Al-Abri MA, Al Lawati I, Zadjali F, Ganguly S. Sleep Patterns and Quality in Omani Adults. Nat Sci Sleep 2020; 12:231-237. [PMID: 32341667 PMCID: PMC7166064 DOI: 10.2147/nss.s233912] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/10/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Sleep patterns have changed continuously worldwide and it can be influenced by social, cultural, and environmental factors. These patterns may be associated with poor sleep quality and daytime sleepiness. The aim of the study was to investigate sleep patterns and quality in Omani adults using actigraphy. SUBJECTS AND METHODS This was a cross-sectional study conducted between June 2015 and February 2017. Four hundred subjects agreed to participate in the study (52% male, 48% female). Subjects were randomly selected and enrolled in the study among young adults and middle aged individuals living in the City of Muscat. Subjects were asked to fill-in Epworth sleepiness scale (ESS) and Pittsburgh sleep quality index (PSQI). Actigraphy was used to measure their sleep patterns for one week. RESULTS The mean age of participants was 32.80±11.50 years. Four sleep patterns were identified: monophasic, bi-phasic (post-dawn), bi-phasic (afternoon siesta), and polyphasic (three sleep periods/24 hours). The study revealed that 35% of participants had biphasic-siesta sleep pattern, 28% polyphasic, 26% monophasic, and 11% biphasic-dawn. The biphasic siesta pattern was found to be associated with younger age group (25-34 years) (P=0.001). Polyphasic sleep was associated with higher ESS score (P=0.001) but not with poor sleep quality (P=0.24). There was no significant difference in night sleep duration among all the sleep patterns (P=0.07) but the polyphasic sleep pattern had higher total 24-hour day sleep duration (P=0.03). Nearly 90% of participants practiced afternoon siestas with mean duration of 45±43 minutes. CONCLUSION The predominant sleep pattern among Omanis was biphasic-siesta and majority of people practiced afternoon siesta. Polyphasic sleep pattern is associated with daytime sleepiness.
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Affiliation(s)
- Mohammed A Al-Abri
- Department of Physiology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Ibtisam Al Lawati
- Department of Physiology, Oman College of Health Sciences, Muscat, Sultanate of Oman
| | - Fahad Zadjali
- Department of Biochemistry, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
| | - Shyam Ganguly
- Department of Family Medicine and Public Health, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Sultanate of Oman
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18
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Abstract
Sleep durations vary greatly across animals from 2 to 20 hours with no clear explanation. A small Mexican cavefish reveals how the brain can adapt to increase its wake-stabilizing hypocretin circuit and dramatically reduce sleep, likely to allow adaptive foraging.
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Affiliation(s)
- Louis C Leung
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford Center for Sleep Sciences and Medicine, Stanford, CA 94305, USA; INSERM 1024, Ecole Normale Supérieure Paris, 75005, France.
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19
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Hozer C, Pifferi F, Aujard F, Perret M. The Biological Clock in Gray Mouse Lemur: Adaptive, Evolutionary and Aging Considerations in an Emerging Non-human Primate Model. Front Physiol 2019; 10:1033. [PMID: 31447706 PMCID: PMC6696974 DOI: 10.3389/fphys.2019.01033] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 07/26/2019] [Indexed: 01/04/2023] Open
Abstract
Circadian rhythms, which measure time on a scale of 24 h, are genetically generated by the circadian clock, which plays a crucial role in the regulation of almost every physiological and metabolic process in most organisms. This review gathers all the available information about the circadian clock in a small Malagasy primate, the gray mouse lemur (Microcebus murinus), and reports 30 years data from the historical colony at Brunoy (France). Although the mouse lemur has long been seen as a "primitive" species, its clock displays high phenotypic plasticity, allowing perfect adaptation of its biological rhythms to environmental challenges (seasonality, food availability). The alterations of the circadian timing system in M. murinus during aging show many similarities with those in human aging. Comparisons are drawn with other mammalian species (more specifically, with rodents, other non-human primates and humans) to demonstrate that the gray mouse lemur is a good complementary and alternative model for studying the circadian clock and, more broadly, brain aging and pathologies.
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20
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Brividoro MV, Kowalewski MM, Scarry CJ, Oklander LI. Patterns of Sleeping Site and Sleeping Tree Selection by Black-and-Gold Howler Monkeys (Alouatta caraya) in Northern Argentina. INT J PRIMATOL 2019. [DOI: 10.1007/s10764-019-00094-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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Latifi B, Adamantidis A, Bassetti C, Schmidt MH. Sleep-Wake Cycling and Energy Conservation: Role of Hypocretin and the Lateral Hypothalamus in Dynamic State-Dependent Resource Optimization. Front Neurol 2018; 9:790. [PMID: 30344503 PMCID: PMC6183196 DOI: 10.3389/fneur.2018.00790] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/31/2018] [Indexed: 12/23/2022] Open
Abstract
The hypocretin (Hcrt) system has been implicated in a wide range of physiological functions from sleep-wake regulation to cardiovascular, behavioral, metabolic, and thermoregulagtory control. These wide-ranging physiological effects have challenged the identification of a parsimonious function for Hcrt. A compelling hypothesis suggests that Hcrt plays a role in the integration of sleep-wake neurophysiology with energy metabolism. For example, Hcrt neurons promote waking and feeding, but are also sensors of energy balance. Loss of Hcrt function leads to an increase in REM sleep propensity, but a potential role for Hcrt linking energy balance with REM sleep expression has not been addressed. Here we examine a potential role for Hcrt and the lateral hypothalamus (LH) in state-dependent resource allocation as a means of optimizing resource utilization and, as a result, energy conservation. We review the energy allocation hypothesis of sleep and how state-dependent metabolic partitioning may contribute toward energy conservation, but with additional examination of how the loss of thermoregulatory function during REM sleep may impact resource optimization. Optimization of energy expenditures at the whole organism level necessitates a top-down network responsible for coordinating metabolic operations in a state-dependent manner across organ systems. In this context, we then specifically examine the potential role of the LH in regulating this output control, including the contribution from both Hcrt and melanin concentrating hormone (MCH) neurons among a diverse LH cell population. We propose that this hypothalamic integration system is responsible for global shifts in state-dependent resource allocations, ultimately promoting resource optimization and an energy conservation function of sleep-wake cycling.
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Affiliation(s)
- Blerina Latifi
- Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Antoine Adamantidis
- Department of Neurology, Center for Experimental Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Department of Biomedical Research, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Claudio Bassetti
- Department of Neurology, Center for Experimental Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Markus H Schmidt
- Department of Neurology, Center for Experimental Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.,Ohio Sleep Medicine Institute, Dublin, OH, United States
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22
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Nunn CL, Samson DR. Sleep in a comparative context: Investigating how human sleep differs from sleep in other primates. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:601-612. [PMID: 29446072 DOI: 10.1002/ajpa.23427] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 01/17/2018] [Accepted: 01/18/2018] [Indexed: 01/19/2023]
Abstract
OBJECTIVES Primates vary in their sleep durations and, remarkably, humans sleep the least per 24-hr period of the 30 primates that have been studied. Using phylogenetic methods that quantitatively situate human phenotypes within a broader primate comparative context, we investigated the evolution of human sleep architecture, focusing on: total sleep duration, rapid eye movement (REM) sleep duration, non-rapid eye movement (NREM) sleep duration, and proportion of sleep in REM. MATERIALS AND METHODS We used two different Bayesian methods: phylogenetic prediction based on phylogenetic generalized least squares and a multistate Onrstein-Uhlenbeck (OU) evolutionary model of random drift and stabilizing selection. RESULTS Phylogenetic prediction confirmed that humans sleep less than predicted for a primate of our body mass, predation risk, brain size, foraging needs, sexual selection, and diet. These analyses further revealed that humans pack an unexpectedly higher proportion of REM sleep within a shorter overall sleep duration, and do so by reducing NREM sleep (rather than increasing REM). The OU model generally confirmed these findings, with shifts along the human lineage inferred for TST, NREM, and proportion of REM, but not for REM. DISCUSSION We propose that the risks and opportunity costs of sleep are responsible for shorter sleep durations in humans, with risks arising from terrestrial sleep involving threats from predators and conspecifics, and opportunity costs because time spent sleeping could be used for learning, creating material objects, and socializing.
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Affiliation(s)
- Charles L Nunn
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina.,Duke Global Health Institute, Duke University, Durham, North Carolina
| | - David R Samson
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina.,Department of Anthropology, University of Toronto, Mississauga, Ontario, Canada
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23
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Chong SYC, Xin L, Ptáček LJ, Fu YH. Disorders of sleep and circadian rhythms. HANDBOOK OF CLINICAL NEUROLOGY 2018; 148:531-538. [PMID: 29478598 DOI: 10.1016/b978-0-444-64076-5.00034-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Sleep is fundamental to the survival of humans. However, knowledge regarding the role of sleep and its regulation is poorly understood. Genetics in flies, mice, and humans has led to a detailed understanding of some aspects of circadian regulation. Sleep homeostasis (the effect of increasing periods of wakefulness on our sleep propensity) is largely not understood. Sleep homeostasis is distinct from, but also linked to, the circadian clock. It is only in the last two decades that our understanding of some sleep disorders has been revealed. These breakthroughs were mostly fueled by intensive investigation using genetic tools. Although modern human genetics has revolutionized scientific research of neurologic disorders beginning ~35 years ago, studies of sleep and sleep disorders have lagged behind those of many neurologic diseases. This is due to the complexity in phenotyping behaviors like sleep and the fact that sleep is strongly influenced by environmental and other factors. We have long been aware that the amount of sleep required by individuals is normally distributed in the general population with small proportions of people being natural short or natural long sleepers. However, it has been less than a decade since Mendelian families of natural short sleepers have been recognized. Recent work has made significant advances and mechanistic insights of several sleep disorders as well as familial natural short sleepers by using ever-improving human genetic and cellular molecular tools. Given recent advances into genetic and biologic understanding of sleep, the hope of understanding this indispensable process is closer. Ultimately, our growing understanding will lead to more effective treatments of human sleep disorders.
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Affiliation(s)
- S Y Christin Chong
- Department of Neurology, University of California, San Francisco, CA, United States
| | - Lijuan Xin
- Department of Neurology, University of California, San Francisco, CA, United States
| | - Louis J Ptáček
- Department of Neurology, University of California, San Francisco, CA, United States; Howard Hughes Medical Institute, San Francisco, CA, United States
| | - Ying-Hui Fu
- Department of Neurology, University of California, San Francisco, CA, United States.
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24
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Abstract
Despite decades of intense study, the functions of sleep are still shrouded in mystery. The difficulty in understanding these functions can be at least partly attributed to the varied manifestations of sleep in different animals. Daily sleep duration can range from 4-20 hrs among mammals, and sleep can manifest throughout the brain, or it can alternate over time between cerebral hemispheres, depending on the species. Ecological factors are likely to have shaped these and other sleep behaviors during evolution by altering the properties of conserved arousal circuits in the brain. Nonetheless, core functions of sleep are likely to have arisen early and to have persisted to the present day in diverse organisms. This review will discuss the evolutionary forces that may be responsible for phylogenetic differences in sleep and the potential core functions that sleep fulfills.
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Affiliation(s)
- William J Joiner
- Department of Pharmacology, University of California San Diego, La Jolla, CA 92093-0636, USA; Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, CA 92093-0636, USA; Neurosciences Graduate Program, University of California San Diego, La Jolla, CA 92093-0636, USA; Center for Circadian Biology, University of California San Diego, La Jolla, CA 92093-0636, USA.
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25
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Gravett N, Bhagwandin A, Lyamin OI, Siegel JM, Manger PR. Sociality Affects REM Sleep Episode Duration Under Controlled Laboratory Conditions in the Rock Hyrax, Procavia capensis. Front Neuroanat 2017; 11:105. [PMID: 29201001 PMCID: PMC5696350 DOI: 10.3389/fnana.2017.00105] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 11/03/2017] [Indexed: 11/18/2022] Open
Abstract
The rock hyrax, Procavia capensis, is a highly social, diurnal mammal. In the current study several physiologically measurable parameters of sleep, as well as the accompanying behavior, were recorded continuously from five rock hyraxes, for 72 h under solitary (experimental animal alone in the recording chamber), and social conditions (experimental animal with 1 or 2 additional, non-implanted animals in the recording chamber). The results revealed no significant differences between solitary and social conditions for total sleep times, number of episodes, episode duration or slow wave activity (SWA) for all states examined. The only significant difference observed between social and solitary conditions was the average duration of rapid eye movement (REM) sleep episodes. REM sleep episode duration was on average 20 s and 40 s longer under social conditions daily and during the dark period, respectively. It is hypothesized that the increase in REM sleep episode duration under social conditions could possibly be attributed to improved thermoregulation strategies, however considering the limited sample size and design of the current study further investigations are needed to confirm this finding. Whether the conclusions and the observations made in this study can be generalized to all naturally socially sleeping mammals remains an open question.
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Affiliation(s)
- Nadine Gravett
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Adhil Bhagwandin
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Oleg I Lyamin
- Department of Psychiatry, School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Brain Research Institute, Neurobiology Research, Sepulveda VA Medical Centre, Los Angeles, CA, United States
| | - Jerome M Siegel
- Department of Psychiatry, School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.,Brain Research Institute, Neurobiology Research, Sepulveda VA Medical Centre, Los Angeles, CA, United States
| | - Paul R Manger
- School of Anatomical Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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26
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Stahl BA, Slocumb ME, Chaitin H, DiAngelo JR, Keene AC. Sleep-Dependent Modulation of Metabolic Rate in Drosophila. Sleep 2017; 40:3852476. [PMID: 28541527 DOI: 10.1093/sleep/zsx084] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/24/2017] [Indexed: 12/17/2022] Open
Abstract
Study Objectives Dysregulation of sleep is associated with metabolic diseases, and metabolic rate (MR) is acutely regulated by sleep-wake behavior. In humans and rodent models, sleep loss is associated with obesity, reduced metabolic rate, and negative energy balance, yet little is known about the neural mechanisms governing interactions between sleep and metabolism. Methods We have developed a system to simultaneously measure sleep and MR in individual Drosophila, allowing for interrogation of neural systems governing interactions between sleep and metabolic rate. Results Like mammals, MR in flies is reduced during sleep and increased during sleep deprivation suggesting sleep-dependent regulation of MR is conserved across phyla. The reduction of MR during sleep is not simply a consequence of inactivity because MR is reduced ~30 minutes following the onset of sleep, raising the possibility that CO2 production provides a metric to distinguish different sleep states in the fruit fly. To examine the relationship between sleep and metabolism, we determined basal and sleep-dependent changes in MR is reduced in starved flies, suggesting that starvation inhibits normal sleep-associated effects on metabolic rate. Further, translin mutant flies that fail to suppress sleep during starvation demonstrate a lower basal metabolic rate, but this rate was further reduced in response to starvation, revealing that regulation of starvation-induced changes in MR and sleep duration are genetically distinct. Conclusions Therefore, this system provides the unique ability to simultaneously measure sleep and oxidative metabolism, providing novel insight into the physiological changes associated with sleep and wakefulness in the fruit fly.
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Affiliation(s)
- Bethany A Stahl
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL
| | - Melissa E Slocumb
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL.,Integrative Biology Graduate Program, Jupiter, FL
| | - Hersh Chaitin
- Department of Ocean and Mechanical Engineering, Florida Atlantic University, Boca Raton, FL
| | | | - Alex C Keene
- Department of Biological Sciences, Florida Atlantic University, Jupiter, FL
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Cerri M, Luppi M, Tupone D, Zamboni G, Amici R. REM Sleep and Endothermy: Potential Sites and Mechanism of a Reciprocal Interference. Front Physiol 2017; 8:624. [PMID: 28883799 PMCID: PMC5573803 DOI: 10.3389/fphys.2017.00624] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/11/2017] [Indexed: 01/11/2023] Open
Abstract
Numerous data show a reciprocal interaction between REM sleep and thermoregulation. During REM sleep, the function of thermoregulation appears to be impaired; from the other hand, the tonic activation of thermogenesis, such as during cold exposure, suppresses REM sleep occurrence. Recently, both the central neural network controlling REM sleep and the central neural network controlling thermoregulation have been progressively unraveled. Thermoregulation was shown to be controlled by a central “core” circuit, responsible for the maintenance of body temperature, modulated by a set of accessory areas. REM sleep was suggested to be controlled by a group of hypothalamic neurons overlooking at the REM sleep generating circuits within the brainstem. The two networks overlap in a few areas, and in this review, we will suggest that in such overlap may reside the explanation of the reciprocal interaction between REM sleep and thermoregulation. Considering the peculiar modulation of thermoregulation by REM sleep the result of their coincidental evolution, REM sleep may therefore be seen as a period of transient heterothermy.
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Affiliation(s)
- Matteo Cerri
- Department of Biomedical and NeuroMotor Sciences, University of BolognaBologna, Italy
| | - Marco Luppi
- Department of Biomedical and NeuroMotor Sciences, University of BolognaBologna, Italy
| | - Domenico Tupone
- Department of Biomedical and NeuroMotor Sciences, University of BolognaBologna, Italy
| | - Giovanni Zamboni
- Department of Biomedical and NeuroMotor Sciences, University of BolognaBologna, Italy
| | - Roberto Amici
- Department of Biomedical and NeuroMotor Sciences, University of BolognaBologna, Italy
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Inactivity/sleep in two wild free-roaming African elephant matriarchs - Does large body size make elephants the shortest mammalian sleepers? PLoS One 2017; 12:e0171903. [PMID: 28249035 PMCID: PMC5382951 DOI: 10.1371/journal.pone.0171903] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 01/28/2017] [Indexed: 01/24/2023] Open
Abstract
The current study provides details of sleep (or inactivity) in two wild, free-roaming African elephant matriarchs studied in their natural habitat with remote monitoring using an actiwatch subcutaneously implanted in the trunk, a standard elephant collar equipped with a GPS system and gyroscope, and a portable weather station. We found that these two elephants were polyphasic sleepers, had an average daily total sleep time of 2 h, mostly between 02:00 and 06:00, and displayed the shortest daily sleep time of any mammal recorded to date. Moreover, these two elephants exhibited both standing and recumbent sleep, but only exhibited recumbent sleep every third or fourth day, potentially limiting their ability to enter REM sleep on a daily basis. In addition, we observed on five occasions that the elephants went without sleep for up to 46 h and traversed around 30 km in 10 h, possibly due to disturbances such as potential predation or poaching events, or a bull elephant in musth. They exhibited no form of sleep rebound following a night without sleep. Environmental conditions, especially ambient air temperature and relative humidity, analysed as wet-bulb globe temperature, reliably predict sleep onset and offset times. The elephants selected novel sleep sites each night and the amount of activity between sleep periods did not affect the amount of sleep. A number of similarities and differences to studies of elephant sleep in captivity are noted, and specific factors shaping sleep architecture in elephants, on various temporal scales, are discussed.
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Mader EC, Mader ACL. Sleep as spatiotemporal integration of biological processes that evolved to periodically reinforce neurodynamic and metabolic homeostasis: The 2m3d paradigm of sleep. J Neurol Sci 2016; 367:63-80. [PMID: 27423566 DOI: 10.1016/j.jns.2016.05.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 05/12/2016] [Accepted: 05/13/2016] [Indexed: 11/19/2022]
Abstract
Sleep continues to perplex scientists and researchers. Despite decades of sleep research, we still lack a clear understanding of the biological functions and evolution of sleep. In this review, we will examine sleep from a functional and phylogenetic perspective and describe some important conceptual gaps in understanding sleep. Classical theories of the biology and evolution of sleep emphasize sensory activation, energy balance, and metabolic homeostasis. Advances in electrophysiology, functional neuroimaging, and neuroplasticity allow us to view sleep within the framework of neural dynamics. With this paradigm shift, we have come to realize the importance of neurodynamic homeostasis in shaping the biology of sleep. Evidently, animals sleep to achieve neurodynamic and metabolic homeostasis. We are not aware of any framework for understanding sleep where neurodynamic, metabolic, homeostatic, chronophasic, and afferent variables are all taken into account. This motivated us to propose the two-mode three-drive (2m3d) paradigm of sleep. In the 2m3d paradigm, local neurodynamic/metabolic (N/M) processes switch between two modes-m0 and m1-in response to three drives-afferent, chronophasic, and homeostatic. The spatiotemporal integration of local m0/m1 operations gives rise to the global states of sleep and wakefulness. As a framework of evolution, the 2m3d paradigm allows us to view sleep as a robust adaptive strategy that evolved so animals can periodically reinforce neurodynamic and metabolic homeostasis while remaining sensitive to their internal and external environment.
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Affiliation(s)
- Edward Claro Mader
- Louisiana State University Health Sciences Center, Department of Neurology, New Orleans, LA 70112, USA.
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Barton RA, Capellini I. Sleep, Evolution and Brains. BRAIN, BEHAVIOR AND EVOLUTION 2016; 87:65-8. [PMID: 26866818 DOI: 10.1159/000443716] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/04/2016] [Indexed: 11/19/2022]
Affiliation(s)
- Robert A Barton
- Evolutionary Anthropology Research Group, Department of Anthropology, Durham University, Durham, UK
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Slocumb ME, Regalado JM, Yoshizawa M, Neely GG, Masek P, Gibbs AG, Keene AC. Enhanced Sleep Is an Evolutionarily Adaptive Response to Starvation Stress in Drosophila. PLoS One 2015; 10:e0131275. [PMID: 26147198 PMCID: PMC4493134 DOI: 10.1371/journal.pone.0131275] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Accepted: 05/06/2015] [Indexed: 01/24/2023] Open
Abstract
Animals maximize fitness by modulating sleep and foraging strategies in response to changes in nutrient availability. Wild populations of the fruit fly, Drosophila melanogaster, display highly variable levels of starvation and desiccation resistance that differ in accordance with geographic location, nutrient availability, and evolutionary history. Further, flies potently modulate sleep in response to changes in food availability, and selection for starvation resistance enhances sleep, revealing strong genetic relationships between sleep and nutrient availability. To determine the genetic and evolutionary relationship between sleep and nutrient deprivation, we assessed sleep in flies selected for desiccation or starvation resistance. While starvation resistant flies have higher levels of triglycerides, desiccation resistant flies have enhanced glycogen stores, indicative of distinct physiological adaptations to food or water scarcity. Strikingly, selection for starvation resistance, but not desiccation resistance, leads to increased sleep, indicating that enhanced sleep is not a generalized consequence of higher energy stores. Thermotolerance is not altered in starvation or desiccation resistant flies, providing further evidence for context-specific adaptation to environmental stressors. F2 hybrid flies were generated by crossing starvation selected flies with desiccation selected flies, and the relationship between nutrient deprivation and sleep was examined. Hybrids exhibit a positive correlation between starvation resistance and sleep, while no interaction was detected between desiccation resistance and sleep, revealing that prolonged sleep provides an adaptive response to starvation stress. Therefore, these findings demonstrate context-specific evolution of enhanced sleep in response to chronic food deprivation, and provide a model for understanding the evolutionary relationship between sleep and nutrient availability.
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Affiliation(s)
- Melissa E Slocumb
- Department of Biology, University of Nevada-Reno, Reno, NV, 89557, United States of America
| | - Josue M Regalado
- Department of Biology, University of Nevada-Reno, Reno, NV, 89557, United States of America
| | - Masato Yoshizawa
- Department of Biology, University of Nevada-Reno, Reno, NV, 89557, United States of America; Department of Biology, University of Hawai'i, Manoa, 96822, United States of America
| | - Greg G Neely
- Neuroscience Division, Garvan Institution, Sydney, NSW 2010, Australia
| | - Pavel Masek
- Department of Biology, University of Nevada-Reno, Reno, NV, 89557, United States of America
| | - Allen G Gibbs
- School of Life Science, University of Nevada-Las Vegas, Las Vegas, NV, 89119, United States of America
| | - Alex C Keene
- Department of Biology, University of Nevada-Reno, Reno, NV, 89557, United States of America
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The energy allocation function of sleep: A unifying theory of sleep, torpor, and continuous wakefulness. Neurosci Biobehav Rev 2014; 47:122-53. [DOI: 10.1016/j.neubiorev.2014.08.001] [Citation(s) in RCA: 163] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/27/2014] [Accepted: 08/02/2014] [Indexed: 12/14/2022]
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34
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McNamara P. Comment on David Haig's 'Troubled sleep': Implications for functions of infant sleep. Evol Med Public Health 2014; 2014:54-6. [PMID: 24614339 PMCID: PMC3982902 DOI: 10.1093/emph/eou009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Affiliation(s)
- Patrick McNamara
- *Corresponding author. Department of Neurology, A9-45, Boston University School of Medicine, Boston, MA, USA. Tel.: +1-857-364-4405; Fax: +1-857-364-4124; E-mail: ;
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Mochida K, Nishikawa M. Sleep duration is affected by social relationships among sleeping partners in wild Japanese macaques. Behav Processes 2013; 103:102-4. [PMID: 24216082 DOI: 10.1016/j.beproc.2013.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 10/09/2013] [Accepted: 10/27/2013] [Indexed: 11/26/2022]
Abstract
Co-sleeping behaviour, such as sharing a sleeping site or bed, should play an important role in determining sleep structure in mammals by mitigating predation pressure and harsh abiotic conditions during sleep. Although environmental factors surrounding sleeping sites have been studied, there is very little information on the effects of the social environment within the site on sleep in animals other than humans. Here, we quantified the duration of nighttime sleep of wild primates during behavioural observations. Wild Japanese macaques (Macaca fuscata yakui) form clusters at sleeping sites, where they huddle with group members. Macaques slept for longer when huddled in sleeping clusters with natal members than in those with non-natal members. A high degree of synchronisation of wakefulness in pairs of macaques huddling in non-natal clusters suggested that their sleep was often interrupted by the wakefulness of huddling members at night. Our results suggest that familiarity and closeness to huddling partners influence sleep duration.
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Affiliation(s)
- Koji Mochida
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8502, Japan; Tropical Biosphere Research Center, University of Ryukyus, Nishihara, Okinawa 903-0213, Japan.
| | - Mari Nishikawa
- Department of Zoology, Graduate School of Science, Kyoto University, Sakyo-Ku, Kyoto 606-8502, Japan
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Horne J. Why REM sleep? Clues beyond the laboratory in a more challenging world. Biol Psychol 2013; 92:152-68. [DOI: 10.1016/j.biopsycho.2012.10.010] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Revised: 09/17/2012] [Accepted: 10/11/2012] [Indexed: 11/16/2022]
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Abstract
Sleep is often viewed as a vulnerable state that is incompatible with behaviours that nourish and propagate species. This has led to the hypothesis that sleep has survived because it fulfills some universal, but as yet unknown, vital function. I propose that sleep is best understood as a variant of dormant states seen throughout the plant and animal kingdoms and that it is itself highly adaptive because it optimizes the timing and duration of behaviour. Current evidence indicates that ecological variables are the main determinants of sleep duration and intensity across species.
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Affiliation(s)
- Jerome M Siegel
- Jerome M. Siegel is at the Department of Psychiatry, School of Medicine, University of California, Los Angeles, California 90095, USA
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