The relationship of sleep with temperature and metabolic rate in a hibernating primate.


STUDY OBJECTIVES: It has long been suspected that sleep is important for regulating body temperature and metabolic-rate. Hibernation, a state of acute hypothermia and reduced metabolic-rate, offers a promising system for investigating those relationships. Prior studies in hibernating ground squirrels report that, although sleep occurs during hibernation, it manifests only as non-REM sleep, and only at relatively high temperatures. In our study, we report data on sleep during hibernation in a lemuriform primate, Cheirogaleus medius. As the only primate known to experience prolonged periods of hibernation and as an inhabitant of more temperate climates than ground squirrels, this animal serves as an alternative model for exploring sleep temperature/metabolism relationships that may be uniquely relevant to understanding human physiology. MEASUREMENTS AND RESULTS: We find that during hibernation, non-REM sleep is absent in Cheirogaleus. Rather, periods of REM sleep occur during periods of relatively high ambient temperature, a pattern opposite of that observed in ground squirrels. Like ground squirrels, however, EEG is marked by ultra-low voltage activity at relatively low metabolic-rates. CONCLUSIONS: These findings confirm a sleep-temperature/metabolism link, though they also suggest that the relationship of sleep stage with temperature/metabolism is flexible and may differ across species or mammalian orders. The absence of non-REM sleep suggests that during hibernation in Cheirogaleus, like in the ground squirrel, the otherwise universal non-REM sleep homeostatic response is greatly curtailed or absent. Lastly, ultra-low voltage EEG appears to be a cross-species marker for extremely low metabolic-rate, and, as such, may be an attractive target for research on hibernation induction.





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Publication Info

Krystal, Andrew D, Bobby Schopler, Susanne Kobbe, Cathy Williams, Hajanirina Rakatondrainibe, Anne D Yoder and Peter Klopfer (2013). The relationship of sleep with temperature and metabolic rate in a hibernating primate. PLoS One, 8(9). p. e69914. 10.1371/journal.pone.0069914 Retrieved from

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Andrew Darrell Krystal

Professor Emeritus of Psychiatry and Behavioral Sciences

My research is focused on better understanding the pathophysiology of sleep disorders and mood disorders and developing improved treatments for these conditions. My primary research tools are: electroencepahlography (EEG), polysomnography (PSG), computer signal analysis and modeling, functional magnetic resonance imaging (fMRI), and positron emission tomograophy (PET). Nearly all of my projects have been carried out with humans, however, projects are ongoing with gene knock-out models in mice, and lemurs in collaboration with the Duke Primate Center. A few representative current studies are: 1) Defining physiologic (EEG, PSG, PET, fMRI) correlates of sleep complaints and subtyping insomnia on the basis of the associated pathophysiology, 2) Studying the relationship of EEG data recorded during non-REM sleep, daytime function, and insomnia treatment response, 3) Developing new pharmacologic and non-pharmacologic treatments for insomnia, 4) Studying the relationship of natural sleep and hibernation-like phenomena (torpor), 5) Predicting depression treatment response on the basis of pre-treatment EEG and structural MRI data.


Anne Daphne Yoder

Braxton Craven Distinguished Professor of Evolutionary Biology

My work integrates field inventory activities with molecular phylogenetic techniques and geospatial analysis to investigate Madagascar, an area of the world that is biologically complex, poorly understood, and urgently threatened. Madagascar has been designated as one of the most critical geographic priorities for conservation action, retaining less than 10% of the natural habitats that existed before human colonization. It is critical that information be obtained as quickly as possible to document the biota that occurs in the remaining and highly threatened forested areas of western Madagascar, to gain an understanding of the evolutionary processes and associated distributional patterns that have shaped this diversity, and to use this information to help set conservation priorities. Phylogenetic and biogeographic analysis of Malagasy vertebrates, each with unique life-history and dispersal characteristics, are conducted to identify areas of high endemism potentially associated with underlying geological features, and also to test for the role that geographic features have played in generating patterns of vertebrate diversity and distribution. My lab also has a significant focus on capacity-building through the education and training of both American and Malagasy students. Research opportunities for American graduate students are enhanced by the formation of Malagasy/American partnerships.


Peter H. Klopfer

Professor Emeritus of Biology

mother-infant attachments in mammals and imprinting in birds

development and control of aggressive behavior, and its neurobiological mechanisms.

causes of species diversity.

hibernation in lemurs

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