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Furrer M, Meier SA, Jan M, Franken P, Sundset MA, Brown SA, Wagner GC, Huber R. Reindeer in the Arctic reduce sleep need during rumination. Curr Biol 2024; 34:427-433.e5. [PMID: 38141616 DOI: 10.1016/j.cub.2023.12.012] [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: 09/02/2023] [Revised: 11/24/2023] [Accepted: 12/06/2023] [Indexed: 12/25/2023]
Abstract
Timing and quantity of sleep depend on a circadian (∼24-h) rhythm and a specific sleep requirement.1 Sleep curtailment results in a homeostatic rebound of more and deeper sleep, the latter reflected in increased electroencephalographic (EEG) slow-wave activity (SWA) during non-rapid eye movement (NREM) sleep.2 Circadian rhythms are synchronized by the light-dark cycle but persist under constant conditions.3,4,5 Strikingly, arctic reindeer behavior is arrhythmic during the solstices.6 Moreover, the Arctic's extreme seasonal environmental changes cause large variations in overall activity and food intake.7 We hypothesized that the maintenance of optimal functioning under these extremely fluctuating conditions would require adaptations not only in daily activity patterns but also in the homeostatic regulation of sleep. We studied sleep using non-invasive EEG in four Eurasian tundra reindeer (Rangifer tarandus tarandus) in Tromsø, Norway (69°N) during the fall equinox and both solstices. As expected, sleep-wake rhythms paralleled daily activity distribution, and sleep deprivation resulted in a homeostatic rebound in all seasons. Yet, these sleep rebounds were smaller in summer and fall than in winter. Surprisingly, SWA decreased not only during NREM sleep but also during rumination. Quantitative modeling revealed that sleep pressure decayed at similar rates during the two behavioral states. Finally, reindeer spent less time in NREM sleep the more they ruminated. These results suggest that they can sleep during rumination. The ability to reduce sleep need during rumination-undisturbed phases for both sleep recovery and digestion-might allow for near-constant feeding in the arctic summer.
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Affiliation(s)
- Melanie Furrer
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland
| | - Sara A Meier
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Maxime Jan
- Center for Integrative Genomics, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland; Bioinformatics Competence Center, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland
| | - Paul Franken
- Center for Integrative Genomics, University of Lausanne, Génopode building, 1015 Lausanne, Switzerland
| | - Monica A Sundset
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Framstredet 39, 9019 Tromsø, Norway
| | - Steven A Brown
- Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Gabriela C Wagner
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Framstredet 39, 9019 Tromsø, Norway; Division of Forest and Forest Resources, Norwegian Institute of Bioeconomy Research, Holtvegen 66, 9016 Tromsø, Norway.
| | - Reto Huber
- Child Development Center and Children's Research Center, University Children's Hospital Zurich, University of Zurich, Steinwiesstrasse 75, 8032 Zurich, Switzerland; Department of Child and Adolescent Psychiatry and Psychotherapy, Psychiatric Hospital Zurich, University of Zurich, Lenggstrasse 31, 8032 Zurich, Switzerland.
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2
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Gübert J, Schneider G, Hahn‐Klimroth M, Dierkes PW. Nocturnal behavioral patterns of African ungulates in zoos. Ecol Evol 2023; 13:e10777. [PMID: 38053790 PMCID: PMC10694388 DOI: 10.1002/ece3.10777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 12/07/2023] Open
Abstract
Currently, most studies on ungulates' behavior are conducted during the daylight hours, but their nocturnal behavior patterns differ from those shown during day. Therefore, it is necessary to observe ungulates' behavior also overnight. Detailed analyses of nocturnal behavior have only been conducted for very prominent ungulates such as Giraffes (Giraffa camelopardalis), African Elephants (Loxodonta africana), or livestock (e.g., domesticated cattle, sheep, or pigs), and the nocturnal rhythms exhibited by many ungulates remain unknown. In the present study, the nocturnal rhythms of 192 individuals of 18 ungulate species from 20 European zoos are studied with respect to the behavioral positions standing, lying-head up, and lying-head down (the typical REM sleep position). Differences between individuals of different age were found, but no differences with respect to the sex were seen. Most species showed a significant increase in the proportion of lying during the night. In addition, the time between two events of "lying down" was studied in detail. A high degree of rhythmicity with respect to this quantity was found in all species. The proportion of lying in such a period was greater in Artiodactyla than in Perissodactyla, and greater in juveniles than in adults.
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Affiliation(s)
- Jennifer Gübert
- Faculty of Biological SciencesGoethe University FrankfurtFrankfurtGermany
| | - Gaby Schneider
- Institute of MathematicsGoethe University FrankfurtFrankfurtGermany
| | | | - Paul W. Dierkes
- Faculty of Biological SciencesGoethe University FrankfurtFrankfurtGermany
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3
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Lyamin OI, Siegel JM, Nazarenko EA, Vu M, Rozhnov VV. Sleep with Open Eyes in Two Species of Deer, the Indian Sambar (Rusa unicolor) and Sika Deer (Cervus nippon). DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2023; 512:295-299. [PMID: 38087016 DOI: 10.1134/s0012496623700679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 07/06/2023] [Accepted: 07/10/2023] [Indexed: 12/18/2023]
Abstract
The relationship between postures, sleep stages and eye state was established in two species of deer, the Indian sambar (Rusa unicolor) and sika deer (Cervus nippon), based on video recording. In both species, the state of rest or behavioral sleep was recorded in the sternal position, holding the head above the ground, and in the lateral position, with the head resting on the croup or on the ground. Rest accounted for at least 80% of the time in these positions. Based on behavior criteria a substantial portion of rest represented slow-wave sleep. Episodes of rapid eye movements (REM sleep) were recorded in the lateral position. They did not exceed 2 min. When the deer were in the sternal posture, they kept their eyes open most of the time: in average 96% of the time in sambars and 82% in sika deer. Episodes of the open eye in this posture lasted up to 8.4 min in sambars and up to 3.3 min in sika deer. In the lateral position, such episodes were 4 and 1.5 times shorter. Sleeping with open eyes in ungulates may be an important mechanism of maintaining vigilance.
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Affiliation(s)
- O I Lyamin
- Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia.
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam.
- University of California in Los Angeles, Los Angeles, USA.
| | - J M Siegel
- University of California in Los Angeles, Los Angeles, USA
| | - E A Nazarenko
- Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam
| | - Manh Vu
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam
| | - V V Rozhnov
- Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam
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4
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Smeltzer EA, Stead SM, Li MF, Samson D, Kumpan LT, Teichroeb JA. Social sleepers: The effects of social status on sleep in terrestrial mammals. Horm Behav 2022; 143:105181. [PMID: 35594742 DOI: 10.1016/j.yhbeh.2022.105181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 04/12/2022] [Accepted: 04/22/2022] [Indexed: 11/18/2022]
Abstract
Social status among group-living mammals can impact access to resources, such as water, food, social support, and mating opportunities, and this differential access to resources can have fitness consequences. Here, we propose that an animal's social status impacts their access to sleep opportunities, as social status may predict when an animal sleeps, where they sleep, who they sleep with, and how well they sleep. Our review of terrestrial mammals examines how sleep architecture and intensity may be impacted by (1) sleeping conditions and (2) the social experience during wakefulness. Sleeping positions vary in thermoregulatory properties, protection from predators, and exposure to parasites. Thus, if dominant individuals have priority of access to sleeping positions, they may benefit from higher quality sleeping conditions and, in turn, better sleep. With respect to waking experiences, we discuss the impacts of stress on sleep, as it has been established that specific social statuses can be characterized by stress-related physiological profiles. While much research has focused on how dominance hierarchies impact access to resources like food and mating opportunities, differential access to sleep opportunities among mammals has been largely ignored despite its potential fitness consequences.
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Affiliation(s)
- E A Smeltzer
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
| | - S M Stead
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada.
| | - M F Li
- Department of Anthropology, University of Toronto, 19 Russell St., Toronto, Ontario M5S 2S2, Canada
| | - D Samson
- Department of Anthropology, University of Toronto Mississauga, 3359 Mississauga Rd., Mississauga, Ontario L5L 1C6, Canada
| | - L T Kumpan
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
| | - J A Teichroeb
- Department of Anthropology, University of Toronto Scarborough, 1265 Military Trail, Scarborough, Ontario M1C 1A4, Canada
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Reicher V, Bálint A, Újváry D, Gácsi M. Non-invasive sleep EEG measurement in hand raised wolves. Sci Rep 2022; 12:9792. [PMID: 35697910 PMCID: PMC9191399 DOI: 10.1038/s41598-022-13643-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 05/17/2022] [Indexed: 11/10/2022] Open
Abstract
Sleep research greatly benefits from comparative studies to understand the underlying physiological and environmental factors affecting the different features of sleep, also informing us about the possible evolutionary changes shaping them. Recently, the domestic dog became an exceedingly valuable model species in sleep studies, as the use of non-invasive polysomnography methodologies enables direct comparison with human sleep data. In this study, we applied the same polysomnography protocol to record the sleep of dog’s closest wild relative, the wolf. We measured the sleep of seven captive (six young and one senior), extensively socialized wolves using a fully non-invasive sleep EEG methodology, originally developed for family dogs. We provide the first descriptive analysis of the sleep macrostructure and NREM spectral power density of wolves using a completely non-invasive methodology. For (non-statistical) comparison, we included the same sleep data of similarly aged dogs. Although our sample size was inadequate to perform statistical analyses, we suggest that it may form the basis of an international, multi-site collection of similar samples using our methodology, allowing for generalizable, unbiased conclusions. As we managed to register both macrostructural and spectral sleep data, our procedure appears to be suitable for collecting valid data in other species too, increasing the comparability of non-invasive sleep studies.
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Affiliation(s)
- Vivien Reicher
- Department of Ethology, Doctoral School of Biology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary. .,MTA-ELTE Comparative Ethology Research Group, Budapest, Hungary.
| | - Anna Bálint
- MTA-ELTE Comparative Ethology Research Group, Budapest, Hungary
| | - Dóra Újváry
- Department of Ethology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
| | - Márta Gácsi
- MTA-ELTE Comparative Ethology Research Group, Budapest, Hungary.,Department of Ethology, Institute of Biology, Eötvös Loránd University, Budapest, Hungary
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6
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Gübert J, Hahn-Klimroth M, Dierkes PW. BOVIDS: A deep learning-based software package for pose estimation to evaluate nightly behavior and its application to common elands ( Tragelaphus oryx) in zoos. Ecol Evol 2022; 12:e8701. [PMID: 35342615 PMCID: PMC8928879 DOI: 10.1002/ece3.8701] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 02/13/2022] [Accepted: 02/17/2022] [Indexed: 12/29/2022] Open
Abstract
Only a few studies on the nocturnal behavior of African ungulates exist so far, with mostly small sample sizes. For a comprehensive understanding of nocturnal behavior, the data basis needs to be expanded. Results obtained by observing zoo animals can provide clues for the study of wild animals and furthermore contribute to a better understanding of animal welfare and better husbandry conditions in zoos. The current contribution reduces the lack of data in two ways. First, we present a stand-alone open-source software package based on deep learning techniques, named Behavioral Observations by Videos and Images using Deep-Learning Software (BOVIDS). It can be used to identify ungulates in their enclosure and to determine the three behavioral poses "Standing," "Lying-head up," and "Lying-head down" on 11,411 h of video material with an accuracy of 99.4%. Second, BOVIDS is used to conduct a case study on 25 common elands (Tragelaphus oryx) out of 5 EAZA zoos with a total of 822 nights, yielding the first detailed description of the nightly behavior of common elands. Our results indicate that age and sex are influencing factors on the nocturnal activity budget, the length of behavioral phases as well as the number of phases per behavioral state during the night while the keeping zoo has no significant influence. It is found that males spend more time in REM sleep posture than females while young animals spend more time in this position than adult ones. Finally, the results suggest a rhythm between the Standing and Lying phases among common elands that opens future research directions.
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Affiliation(s)
- Jennifer Gübert
- Faculty of Biological Sciences Bioscience Education and Zoo Biology Goethe University Frankfurt Germany
| | | | - Paul W Dierkes
- Faculty of Biological Sciences Bioscience Education and Zoo Biology Goethe University Frankfurt Germany
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7
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Loftus JC, Harel R, Núñez CL, Crofoot MC. Ecological and social pressures interfere with homeostatic sleep regulation in the wild. eLife 2022; 11:73695. [PMID: 35229719 PMCID: PMC8887896 DOI: 10.7554/elife.73695] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 01/18/2022] [Indexed: 12/12/2022] Open
Abstract
Sleep is fundamental to the health and fitness of all animals. The physiological importance of sleep is underscored by the central role of homeostasis in determining sleep investment – following periods of sleep deprivation, individuals experience longer and more intense sleep bouts. Yet, most sleep research has been conducted in highly controlled settings, removed from evolutionarily relevant contexts that may hinder the maintenance of sleep homeostasis. Using triaxial accelerometry and GPS to track the sleep patterns of a group of wild baboons (Papio anubis), we found that ecological and social pressures indeed interfere with homeostatic sleep regulation. Baboons sacrificed time spent sleeping when in less familiar locations and when sleeping in proximity to more group-mates, regardless of how long they had slept the prior night or how much they had physically exerted themselves the preceding day. Further, they did not appear to compensate for lost sleep via more intense sleep bouts. We found that the collective dynamics characteristic of social animal groups persist into the sleep period, as baboons exhibited synchronized patterns of waking throughout the night, particularly with nearby group-mates. Thus, for animals whose fitness depends critically on avoiding predation and developing social relationships, maintaining sleep homeostasis may be only secondary to remaining vigilant when sleeping in risky habitats and interacting with group-mates during the night. Our results highlight the importance of studying sleep in ecologically relevant contexts, where the adaptive function of sleep patterns directly reflects the complex trade-offs that have guided its evolution.
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Affiliation(s)
- J Carter Loftus
- Department of Anthropology, University of California, Davis, Davis, United States.,Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Department of Biology, University of Konstanz, Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.,Mpala Research Centre, Nanyuki, Kenya.,Animal Behavior Graduate Group, University of California, Davis, Davis, United States
| | - Roi Harel
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Mpala Research Centre, Nanyuki, Kenya
| | - Chase L Núñez
- Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.,Mpala Research Centre, Nanyuki, Kenya
| | - Margaret C Crofoot
- Department of Anthropology, University of California, Davis, Davis, United States.,Department for the Ecology of Animal Societies, Max Planck Institute of Animal Behavior, Konstanz, Germany.,Department of Biology, University of Konstanz, Konstanz, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Konstanz, Germany.,Mpala Research Centre, Nanyuki, Kenya.,Animal Behavior Graduate Group, University of California, Davis, Davis, United States
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8
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Lyamin OI, Siegel JM, Evsigneev RV, Nazarenko EA, Rozhnov VV. Characteristics of Sleep-Wakefulness Cycle and Circadian Activity in the Lesser Mouse-Deer (Tragulus kanchil). DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2021; 500:153-158. [PMID: 34731381 PMCID: PMC8837905 DOI: 10.1134/s0012496621050069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 05/23/2021] [Accepted: 05/23/2021] [Indexed: 06/13/2023]
Abstract
The pattern of sleep and circadian activity of the lesser mouse-deer (Tragulus kanchil) that is the smallest (body mass between 1.5 and 2.2 kg) representative of the basal group (Tragulidae) of even-toed ungulates which evolved 40-50 Ma were studied. In naturalistic conditions, a total of 30 days of full-day video of the animal behavior and 15 days of 24-h polysomnographic data were collected in 6 animals. The mouse-deer were active less than 20% of 24 h and were quiescent during 60-80% of the remaining time. Slow wave sleep (SWS) accounted for on average 49.7 ± 3.7% of 24 h and paradoxical (rapid eye movement, REM) sleep accounted for 1.7 ± 0.3% of 24 h. During the majority of SWS (87.0 ± 4.4%) the eyes were open. The most of SWS and REM sleep occurred during the daytime hours (9 a.m. to 4 p.m.) and in the first half of the night (8 p.m. to 2 a.m.); the animals were most active during twilight hours (4-6 a.m. and 6-7 p.m.). We suggest that the main features of sleep in the mouse-deer are largely determined by ecological factors, including environmental temperature and predation, as well as the size and physiology of the mouse-deer.
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Affiliation(s)
- O I Lyamin
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071, Moscow, Russia.
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam.
- University of California in Los Angeles, 90095, Los Angeles, CA, United States.
| | - J M Siegel
- University of California in Los Angeles, 90095, Los Angeles, CA, United States
| | | | - E A Nazarenko
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071, Moscow, Russia
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam
| | - V V Rozhnov
- Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, 119071, Moscow, Russia
- Joint Russian-Vietnam Tropical Research and Technological Center, Hanoi, Vietnam
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9
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Lyamin OI, Siegel JM, Nazarenko EA, Rozhnov VV. Sleep in the lesser mouse-deer (Tragulus kanchil). Sleep 2021; 45:6346614. [PMID: 34370021 DOI: 10.1093/sleep/zsab199] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
The mouse-deer or chevrotains are the smallest of the ungulates and ruminants. They are characterized by a number of traits which are considered plesiomorphic for the Artiodactyla order. The objective of this study was to examine sleep in the lesser mouse-deer (Tragulus kanchil), which is the smallest in this group (body mass <2.2 kg). Electroencephalogram, nuchal electromyogram, electrooculogram and body acceleration were recorded in 4 adult mouse-deer females using a telemetry system in Bu Gia Map National Park in Vietnam. The mouse-deer spent on average 49.7±3.0% of 24-h in NREM sleep. REM sleep occupied 1.7±0.3% of 24-h or 3.2±0.5% of total sleep time. The average duration of REM sleep episodes was 2.0±0.2 min, the average maximum was 5.1±1.1 min, and the longest episodes lasted 8 min. NREM sleep occurred in sternal recumbency with the head heals above the ground while 64.7+6.4% of REM sleep occurred with the head resting on the ground. The eyes were open throughout most of the NREM sleep period. The mouse-deer displayed polyphasic sleep and crepuscular peaks in activity (04:00-06:00 and 18:00-19:00). The largest amounts of NREM occurred in the morning (06:00-09:00) and the smallest before dusk (at 04:00-06:00). REM sleep occurred throughout most of the daylight hours (08:00-16:00) and in the first half of the night (19:00-02:00). We suggest that the pattern and timing of sleep in the lesser mouse-deer is adapted to the survival of a small herbivorous animal, subject to predation, living in high environmental temperatures in tropical forest undergrowth.
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Affiliation(s)
- Oleg I Lyamin
- A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia.,Joint Russian- Vietnamese Tropical Research and Technological Center, Hanoi, Vietnam.,Department of Psychiatry, University of California Los Angeles, Los Angeles, CA, USA
| | - Jerome M Siegel
- Department of Psychiatry, University of California Los Angeles, Los Angeles, CA, USA
| | - Evgeny A Nazarenko
- A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia.,Joint Russian- Vietnamese Tropical Research and Technological Center, Hanoi, Vietnam
| | - Viatcheslav V Rozhnov
- A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, Moscow, Russia.,Joint Russian- Vietnamese Tropical Research and Technological Center, Hanoi, Vietnam
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