Psychology Wiki

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language | Individual differences | Personality | Philosophy | Social |
Methods | Statistics | Clinical | Educational | Industrial | Professional items | World psychology |

Animals · Animal ethology · Comparative psychology · Animal models · Outline · Index

Hibernation is an aspect of dormancy and is a state of inactivity and metabolic depression in animals, characterized by lower body temperature, slower breathing, and lower metabolic rate. Hibernation conserves energy, especially during winter. Hibernation may last several days or weeks depending on species, ambient temperature, and time of year. The typical winter season for a hibernator is characterized by periods of hibernation interrupted by sporadic euthermic arousals wherein body temperature is restored to typical values. Hibernation allows animals to conserve energy during the winter when food is short. During hibernation, animals drastically lower their metabolism so as to tap energy reserves stored as body fat at a slower rate.

A similar period of dormancy in summer is known as aestivation


European Hedgehog

Hibernating animals[]

Animals that hibernate include bats, some species of ground squirrels and other rodents, mouse lemurs, the West European Hedgehog and other insectivores, monotremes and marsupials. Even some rattlesnakes, such as the Western Diamondback, are known to hibernate in caves every winter. Historically, Pliny the Elder believed that swallows hibernated, and ornithologist Gilbert White pointed to anecdotal evidence in The Natural History of Selborne that indicated as much. Birds typically do not hibernate, instead utilizing torpor. However the Common Poorwill does hibernate.[1] Many experts believe that the processes of daily torpor and hibernation form a continuum.[How to reference and link to summary or text]

One animal that some famously consider a hibernator is the bear. However, during a bear's winter sleep state, the degree of metabolic depression is much less than what is observed in smaller mammals. Many prefer to use the term "denning" in place of hibernating. The bear's body temperature remains relatively stable (depressed from 37°C to approximately 31°C) and it can be easily aroused. In contrast, hibernating ground squirrels may have core body temperatures as low as -2°C. Some reptile species are said to brumate, or undergo brumation, but the connection to this phenomenon with hibernation is not clear.

Before entering hibernation most species eat a large amount of food and store energy in fat deposits in order to survive the winter. Some species of mammals hibernate while gestating young, which are born shortly after the mother stops hibernating.

For a couple of generations during the 20th century it was thought that basking sharks settled to the floor of the North Sea and hibernated; however, research by Dr David Sims in 2003 dispelled this hypothesis,[2] showing that the sharks actively travelled huge distances throughout the seasons, tracking the areas with the highest quantity of plankton.

The epaulette sharks have been documented to be able to survive for long periods of time without oxygen, even being left high and dry, and at temperatures of up to 26 °C.[3] Other animals able to survive long periods without oxygen include the goldfish, the red-eared slider turtle, the wood frog, and the bar-headed goose.[4]

Until recently no primate, and no tropical mammal, was known to hibernate. However, animal physiologist Kathrin Dausmann of Philipps University of Marburg, Germany, and coworkers presented evidence in the 24 June 2004 edition of Nature that the Fat-tailed Dwarf Lemur of Madagascar hibernates in tree holes for seven months of the year. This is interesting because Malagasy winter temperatures sometimes rise to over 30 °C (86 °F), so hibernation is not exclusively an adaptation to low ambient temperatures. The hibernation of this lemur is strongly dependent on the thermal behaviour of its tree hole: if the hole is poorly insulated, the lemur's body temperature fluctuates widely, passively following the ambient temperature; if well insulated, the body temperature stays fairly constant and the animal undergoes regular spells of arousal. Dausmann found that hypometabolism in hibernating animals is not necessarily coupled to a low body temperature.

Noise and vibration from snowmobiles, all-terrain vehicles and the like is said to sometimes awaken hibernating animals, who may suffer severely or die as a result of premature awakening in times of food shortage.[How to reference and link to summary or text]

Human hibernation[]

There are many research projects currently investigating how to achieve "induced hibernation" in humans.[1][2] This ability to hibernate humans would be useful for a number of reasons, such as saving the lives of seriously ill or injured people by temporarily putting them in a state of hibernation until treatment can be given. NASA is also interested in possibly putting astronauts in hibernation when going on very long space journeys, making it possible one day to visit far away stars.

Neurophysiology of hibernation[]

See also[]

  • Animal biological rhythms
  • Diapause - a state of metabolic dormancy that requires specific stimuli to trigger and release
  • Dormancy - a period when development is temporarily suspended
  • Estivation - a state of dormancy similar to hibernation, except it is used in the summer
  • Hibernation induction trigger
  • Suspended animation - also similar to hibernation, but induced artificially
  • Torpor - regulated hypothermia for less than a day, often used by birds


  1. Jaeger, E.C. 1948. "Does the poorwill hibernate?" Condor 50:45-46.
  2. (2003) Seasonal movements and behaviour of basking sharks from archival tagging. Marine Ecology Progress Series (248): 187-196.
  3. (08 March 2003)A Shark With an Amazing Party Trick. New Scientist 177 (2385): 46.
  4. Breathless: A shark with an amazing party trick is teaching doctors how to protect the brains of stroke patients. Douglas Fox, New Scientist vol 177 issue 2385 - 08 March 2003, page 46. Last accessed November 9, 2006.

Further reading[]

  • Alloway, T. M., Riedesel, M. L., & McNamara, M. C. (1973). Hibernation: Effects on memory or performance? : Science Vol 181(4094) Jul 1973, 86-87.
  • Andersen, J. (2006). Mechanisms in the shift of a riparian ground beetle (Carabidae) between reproduction and hibernation habitat: Journal of Insect Behavior Vol 19(5) Sep 2006, 545-558.
  • Arnold, W. (1990). The evolution of marmot sociality: II. Costs and benefits of joint hibernation: Behavioral Ecology and Sociobiology Vol 27(4) Oct 1990, 239-246.
  • Bachman, G. C. (1993). Physiological and behavioral ecology of energy acquisition in belding's ground squirrels: Dissertation Abstracts International.
  • Barnes, B. M., & York, A. D. (1990). Effect of winter high temperatures on reproduction and circannual rhythms in hibernating ground squirrels: Journal of Biological Rhythms Vol 5(2) Sum 1990, 119-130.
  • Beckman, A. L., Beaver, T. A., & Lewis, F. A. (1993). Morphine physical dependence in the hibernator: Central nervous system mechanisms underlying the development of dependence remain functional during depression induced by pentobarbital anesthesia: Life Sciences Vol 52(13) 1993, 1079-1086.
  • Beckman, A. L., Dean, R. R., & Wamsley, J. K. (1986). Hippocampal and cortical opioid receptor binding: Changes related to the hibernation state: Brain Research Vol 386(1-2) Oct 1986, 223-231.
  • Beckman, A. L., & Llados-Eckman, C. (1985). Antagonism of brain opioid peptide action reduces hibernation bout duration: Brain Research Vol 328(2) Mar 1985, 201-205.
  • Beckman, A. L., Llados-Eckman, C., Stanton, T. L., & Adler, M. W. (1981). Physical dependence on morphine fails to develop during the hibernating state: Science Vol 212(4502) Jun 1981, 1527-1528.
  • Berger, R. J. (1984). Slow wave sleep, shallow torpor and hibernation: Homologous states of diminished metabolism and body temperature: Biological Psychology Vol 19(3-4) Dec 1984, 305-326.
  • Berger, R. J., & Phillips, N. H. (1995). Energy conservation and sleep: Behavioural Brain Research Vol 69(1-2) Jul-Aug 1995, 65-73.
  • Boshes, M. (1979). An analysis of feeding behaviour and feeding patterns in two species of hibernating rodents, the golden-mantled ground squirrel, Spermophilus lateralis, and the edible dormouse, Glis glis: Dissertation Abstracts International.
  • Bruce, D. S., Ambler, D. L., Henschel, T. M., Oeltgen, P. R., & et al. (1992). Suppression of guinea pig ileum induced contractility by plasma albumin of hibernators: Pharmacology, Biochemistry and Behavior Vol 43(1) Sep 1992, 199-203.
  • Bugaev, S. A., & Nikitina, E. V. (1984). Physiological mechanisms of the "arousal response" in animals in a state of hypobiosis: Neuroscience and Behavioral Physiology Vol 14(6) Nov-Dec 1984, 516-519.
  • Campbell, J. W. (1985). The central effects of bombesin on thermoregulation in euthermic and hibernating ground squirrels (Spermophilus lateralis) with accompanying stereotaxic atlas of the brain of this species: Dissertation Abstracts International.
  • Canguilhem, B., Schmitt, P., Mack, G., & Kempf, E. (1977). Feeding behavior, circannual body weight and hibernation rhythms in European hamsters lesioned in the noradrenergic ascending bundles: Physiology & Behavior Vol 18(6) Jun 1977, 1067-1074.
  • Chauhan, V. P. S., Tsiouris, J. A., Chauhan, A., Sheikh, A. M., Brown, W. T., & Vaughan, M. (2002). Increased oxidative stress and decreased activities of Ca-super(2+)/Mg-super(2+)-ATPase and Na-super(+) / K-super(+)-ATPase in the red blood cells of the hibernating black bear: Life Sciences Vol 71(2) May 2002, 153-161.
  • Dahbi, A., & Lenoir, A. (1998). Nest separation and the dynamics of the Gestalt odor in the polydomous ant Cataglyphis iberica (Hymenoptera, Formicidae): Behavioral Ecology and Sociobiology Vol 42(5) May 1998, 349-355.
  • Danion, J. M., Canguilhem, B., Bentz, I., Imbs, J. L., & et al. (1990). Long-term lithium treatment does not suppress hibernation in European hamsters: Neuropsychobiology Vol 23(1) 1990, 31-37.
  • Dapporto, L., Pansolli, C., & Turillazzi, S. (2004). Hibernation clustering and its consequences for associative nest foundation in Polistes dominulus (Hymenoptera Vespidae): Behavioral Ecology and Sociobiology Vol 56(4) Aug 2004, 315-321.
  • Dark, J., & Miller, D. R. (1997). Metabolic fuel privation in hibernating and awake ground squirrels: Physiology & Behavior Vol 63(1) Dec 1997, 59-65.
  • Dark, J., Miller, D. R., Lewis, D. A., Fried, S. K., & Bunkin, D. (2003). Noradrenaline-lnduced Lipolysis in Adipose Tissue is Suppressed at Hibernation Temperatures in Ground Squirrels: Journal of Neuroendocrinology Vol 15(5) May 2003, 451-458.
  • Duchateau, M. J., Velthuis, H. H. W., & Boomsma, J. J. (2004). Sex ratio variation in the bumblebee Bombus terrestris: Behavioral Ecology Vol 15(1) Jan 2004, 71-82.
  • Golovina, T. N., Malikov, U. M., Shortanova, T. K., & Doemin, N. N. (1985). The proteins and RNA in the neuron-neuroglia system of the ground squirrel brain n. raphe dorsalis during hibernation: Fiziologicheskii Zhurnal SSSR im I M Sechenova Vol 71(8) 1985, 945-951.
  • Hallonquist, J. D. (1979). A comparison of normal and lateral hypothalamic electrically induced feeding in two hibernators, Citellus lateralis and Glis glis: Dissertation Abstracts International.
  • Harlow, H. J. (1980). Behavioral and physiological adaptations by the American badger, Taxidea taxus, to food deprivation and cold: Dissertation Abstracts International.
  • Harrington, M. E., Biello, S. M., & Panula, P. (2000). Effects of histamine on circadian rhythms and hibernation: Biological Rhythm Research Vol 31(3) Jul 2000, 374-390.
  • Hartig, W., Stieler, J., Boerema, A. S., Wolf, J., Schmidt, U., Weissfuss, J., et al. (2007). Hibernation model of tau phosphorylation in hamsters: Selective vulnerability of cholinergic basal forebrain neurons--Implications for Alzheimer's disease: European Journal of Neuroscience Vol 25(1) Jan 2007, 69-80.
  • Haskell, E. H., Walker, J. M., & Berger, R. J. (1979). Effects of cold stress on sleep of an hibernator, the golden-mantled ground squirrel (C. lateralis): Physiology & Behavior Vol 23(6) Dec 1979, 1119-1121.
  • Heller, H. C. (1979). Hibernation: Neural aspects: Annual Review of Physiology Vol 41 1979, 305-321.
  • Hill, V. L., & Florant, G. L. (2000). The effect of linseed oil diet on hibernation in yellow-bellied marmots (Marmota flaviventris): Physiology & Behavior Vol 68(4) Feb 2000, 431-437.
  • Holmes, W. G., & Landau, I. T. (1986). Vaginal estrus in unmated Belding's ground squirrels: Hormones and Behavior Vol 20(2) Jun 1986, 243-248.
  • Hudson, J. W., & Wang, L. C. (1979). Hibernation: Endocrinologic aspects: Annual Review of Physiology Vol 41 1979, 287-303.
  • Jeppesen, L. L. (1977). Photoperiodic control of hibernation in Helix pomatia L. (Gastropoda: Pulmonata): Behavioural Processes Vol 2(4) Dec 1977, 373-382.
  • Katbamna, B., Thodi, C., & Senturia, J. B. (1996). Auditory-evoked brainstem responses in the torpid deermouse: Physiology & Behavior Vol 59(1) Jan 1996, 189-194.
  • Kolaeva, S. G. (1978). Role of endogenous and exogenous components in formation of seasonal rhythms in hibernants: Waking & Sleeping Vol 2(1) Jan 1978, 17-20.
  • Konnerth, T. K. (1980). Female facilitation of social emergence from hibernation in the male Anolis carolinensis: Dissertation Abstracts International.
  • Kortner, G., & Geiser, F. (2000). The temporal organization of daily torpor and hibernation: Circadian and circannual rhythms: Chronobiology International Vol 17(2) 2000, 103-128.
  • Krajci, D., & Malinsky, J. (1974). Ultrastructure and histochemistry of spinal ganglia in hibernating hedgehog: Activitas Nervosa Superior Vol 16(2) May 1974, 103-104.
  • Krilowicz, B. L., Edgar, D. M., & Heller, H. C. (1989). Action potential duration increases as body temperature decreases during hibernation: Brain Research Vol 498(1) Sep 1989, 73-80.
  • Krohmer, R. W., & Crews, D. (1987). Temperature activation of courtship behavior in the male red-sided garter snake (Thamnophis sirtalis parietalis): Role of the anterior hypothalamus-preoptic area: Behavioral Neuroscience Vol 101(2) Apr 1987, 228-236.
  • Lind, H. (1989). Homing to hibernating sites in Helix pomatia involving detailed long-term memory: Ethology formerly Zeitschrift fur Tierpsychologie Vol 81(3) Mar 1989, 221-234.
  • Lyman, C. P., O'Brien, R. C., Greene, G. C., & Papafrangos, E. D. (1981). Hibernation and longevity in the Turkish hamster Mesocricetus brandti: Science Vol 212(4495) May 1981, 668-670.
  • Madeo, M., Granata, T., Facciolo, R. M., Tripepi, S., & Canonaco, M. (2006). Feeding Differences in Pubertal and Aged Golden Hamsters (Mesocricetus auratus) Are Related to Specific Cerebral Expression Pattern of Histamine Subtype 3 Receptor: Behavioral Neuroscience Vol 120(6) Dec 2006, 1235-1241.
  • Magarinos, A. M., McEwen, B. S., Saboureau, M., & Pevet, P. (2006). Rapid and reversible changes in intrahippocampal connectivity during the course of hibernation in European hamsters: PNAS Proceedings of the National Academy of Sciences of the United States of America Vol 103(49) Dec 2006, 18775-18780.
  • Malinska, J., Malinsky, J., & Krajci, D. (1974). Light, electron microscopical, and histochemical study of motor nerve cells in spinal cord of hibernating and non-hibernating hedgehog: Activitas Nervosa Superior Vol 16(2) May 1974, 105.
  • Mateo, J. M., & Johnston, R. E. (2000). Retention of social recognition after hibernation in Belding's ground squirrels: Animal Behaviour Vol 59(3) Mar 2000, 491-499.
  • McNamara, M. C., & Riedesel, M. L. (1973). Memory and hibernation in Citellus lateralis: Science Vol 179(4068) Jan 1973, 92-94.
  • Melnyk, R. B. (1981). Insulin-induced feeding in hibernators: Behavioral & Neural Biology Vol 32(1) May 1981, 70-78.
  • Mendonica, M. T., Tousignant, A. J., & Crews, D. (1996). Courting and noncourting male red-sided garter snakes, Thammophis sirtalis parietalis: Plasma melatonin levels and the effects of pinealectomy: Hormones and Behavior Vol 30(2) Jun 1996, 176-185.
  • Meyers, P. E. (1977). Induction of hibernation in the big brown bat, Eptesicus fuscus, by means of intermittent photic stimulation: Dissertation Abstracts International.
  • Michener, G. R. (1983). Spring emergence schedules and vernal behavior of Richardson's ground squirrels: Why do males emerge from hibernation before females? : Behavioral Ecology and Sociobiology Vol 14(1) 1983, 29-38.
  • Miller, V. M., & South, F. E. (1981). Entry into hibernation in M. flaviventris: Sleep and behavioral thermoregulation: Physiology & Behavior Vol 27(6) Dec 1981, 989-993.
  • Millesi, E., Prossinger, H., Dittami, J. P., & Fieder, M. (2001). Hibernation effects on memory in European ground squirrels ( Spermophilus citellus ): Journal of Biological Rhythms Vol 16(3) Jun 2001, 264-271.
  • Miro, J. L., Canguilhem, B., & Schmitt, P. (1980). Effects of bulbectomy on hibernation, food intake and body weight in the European hamsters, Cricetus cricetus: Physiology & Behavior Vol 24(5) May 1980, 859-862.
  • Mosser, H. C., Boucher, R. R., MacCreadie, T. M., Newman, J. R., & et al. (1995). Morphine antinociception in the non-hibernating and hibernating states of the ground squirrel (Citellus lateralis): Life Sciences Vol 57(15) Sep 1995, 1441-1449.
  • Mrosovsky, N. (1988). Seasonal affective disorder, hibernation, and annual cycles in animals: Chipmunks in the sky: Journal of Biological Rhythms Vol 3(2) Sum 1988, 189-207.
  • Mrosovsky, N. (1989). Seasonal affective disorder, hibernation, and annual cycles in animals: Chipmunks in the sky. New York, NY: Guilford Press.
  • Mrosovsky, N., & Barnes, D. S. (1974). Anorexia, food deprivation and hibernation: Physiology & Behavior Vol 12(2) Feb 1974, 265-270.
  • Mrosovsky, N., & Sherry, D. F. (1980). Animal anorexias: Science Vol 207(4433) Feb 1980, 837-842.
  • Muchlinski, A. E. (1980). The effects of daylength and temperature on the hibernating rhythm of the meadow jumping mouse (Zapus hudsonius): Dissertation Abstracts International.
  • Myers, R. D., Oeltgen, P. R., & Spurrier, W. A. (1981). Hibernation "trigger" injected in brain induces hypothermia and hypophagia in the monkey: Brain Research Bulletin Vol 7(6) Dec 1981, 691-695.
  • Nelson, R. J., Mason, R. T., Krohmer, R. W., & Crews, D. (1987). Pinealectomy blocks vernal courtship behavior in red-sided garter snakes: Physiology & Behavior Vol 39(2) 1987, 231-233.
  • Oeltgen, P. R., & et al. (1982). Hibernation "trigger": Opioid-like inhibitory action on brain function of the monkey: Pharmacology, Biochemistry and Behavior Vol 17(6) Dec 1982, 1271-1274.
  • Osborne, P. G., & Hashimoto, M. (2006). Brain antioxidant levels in hamsters during hibernation, arousal and cenothermia: Behavioural Brain Research Vol 168(2) Mar 2006, 208-214.
  • Osborne, P. G., & Hashimoto, M. (2007). Brain ECF antioxidant interactions in hamsters during arousal from hibernation: Behavioural Brain Research Vol 178(1) Mar 2007, 115-122.
  • Palchykova, S., Deboer, T., & Tobler, I. (2002). Selective sleep deprivation after daily torpor in the Djungarian hamster: Journal of Sleep Research Vol 11(4) Dec 2002, 313-319.
  • Pigage, J. C. (1981). Natural and hormonally induced changes of the reproductive organs and pineal gland activity during hibernation in the ground squirrel, Spermophilus richardsonii: Dissertation Abstracts International.
  • Popova, N. K. (1975). Effect of serotonin on arousing from hibernation: Fiziologicheskii Zhurnal SSSR im I M Sechenova Vol 61(1) Jan 1975, 153-156.
  • Popova, N. K., Voronova, I. P., & Kulikov, A. V. (1993). Involvement of brain tryptophan hydroxylase in the mechanism of hibernation: Pharmacology, Biochemistry and Behavior Vol 46(1) Sep 1993, 9-13.
  • Ralevic, V., Knight, G., & Burnstock, G. (1998). Effects of hibernation and arousal from hibernation on mesenteric arterial responses of the golden hamster: Journal of Pharmacology and Experimental Therapeutics Vol 287(2) Nov 1998, 521-526.
  • Ropski, S. J. (1984). Hibernation of the meadow jumping mouse, Zapus hudsonius: Some physiological and ecological implications: Dissertation Abstracts International.
  • Ruby, N. F., Dark, J., Burns, D. E., Heller, H. C., & Zucker, I. (2002). The suprachiasmatic nucleus is essential for circadian body temperature rhythms in hibernating ground squirrels: Journal of Neuroscience Vol 22(1) Jan 2002, 357-364.
  • Ruby, N. F., Zucker, I., Licht, P., & Dark, J. (1993). Olfactory bulb removal lengthens the period of circannual rhythms and disrupts hibernation in golden-mantled ground squirrels: Brain Research Vol 608(1) Apr 1993, 1-6.
  • Ruckebusch, Y., & Toutain, P. L. (1977). A phylogenetic study of sleep: Confrontations Psychiatriques Vol 10(15) 1977, 9-48.
  • Sallmen, T., Beckman, A. L., Stanton, T. L., Eriksson, K. S., Tarhanen, J., Tuomisto, L., et al. (1999). Major changes in the brain histamine system of the ground squirrel Citellus lateralis during hibernation: Journal of Neuroscience Vol 19(5) Mar 1999, 1824-1835.
  • Sallmen, T., Lozada, A. F., Anichtchik, O. V., Beckman, A. L., Leurs, R., & Panula, P. (2003). Changes in Hippocampal Histamine Receptors Across the Hibernation Cycle in Ground Squirrels: Hippocampus Vol 13(6) 2003, 745-754.
  • Sallmen, T., Lozada, A. F., Beckman, A. L., & Panula, P. (2003). Intrahippocampal histamine delays arousal from hibernation: Brain Research Vol 966(2) Mar 2003, 317-320.
  • Satinoff, E., Adler, N., Kraus, H., & Flammino, F. (1975). Paradoxical sleep duration during lights-off and lights-on in ground squirrels: Physiology & Behavior Vol 15(5) Nov 1975, 631-632.
  • Schulke, O., & Ostner, J. (2007). Physiological ecology of cheirogaleid primates: Variation in hibernation and torpor: Acta Ethologica Vol 10(1) Apr 2007, 13-21.
  • Sollertinskaya, T. N., Nuritdinov, E. N., & Obukhova, M. F. (1992). The role of dermorphin in the regulation of hibernation processes in mammals: Fiziologicheskii Zhurnal SSSR im I M Sechenova Vol 78(4) Apr 1992, 1-13.
  • Spieth, H. R., Xue, F., & Strauss, K. (2004). Induction and Inhibition of Diapause by the Same Photoperiod: Experimental Evidence for a "Double Circadian Oscillator Clock": Journal of Biological Rhythms Vol 19(6) Dec 2004, 483-492.
  • Stanton, T. L., Caine, S. B., & Winokur, A. (1992). Seasonal and state-dependent changes in brain TRH receptors in hibernating ground squirrels: Brain Research Bulletin Vol 28(6) Jun 1992, 877-886.
  • Stanton, T. L., Craft, C. M., & Reiter, R. J. (1984). Decreases in pineal melatonin content during the hibernation bout in the golden-mantled ground squirrel, Spermophilus lateralis: Life Sciences Vol 35(14) Oct 1984, 1461-1467.
  • Stone, C. P. (1927). Recent contributions to the experimental literature on native or congenital behavior: Psychological Bulletin Vol 24(1) Jan 1927, 36-61.
  • Tamura, Y., Shintani, M., Nakamura, A., Monden, M., & Shiomi, H. (2005). Phase-specific central regulatory systems of hibernation in Syrian hamsters: Brain Research Vol 1045(1-2) May 2005, 88-96.
  • Terada, A., & Ibuka, N. (2000). Age affects hibernation in syrian hamsters (mesocricetus auratus): Chronobiology International Vol 17(5) 2000, 623-630.
  • Toutain, P. L., & Ruckebusch, Y. (1975). Arousal as a cyclic phenomenon during sleep and hibernation in the hedgehog (Erinaceus europeanus): Experientia Vol 31(3) 1975, 312-314.
  • Ueda, S., & Ibuka, N. (1995). An analysis of factors that induce hibernation in Syrian hamsters: Physiology & Behavior Vol 58(4) Oct 1995, 653-657.
  • Walker, J. M. (1979). Sleep, daily torpor, and hibernation: Continuous processes of energy conservation: Dissertation Abstracts International.
  • Walker, J. M., Garber, A., Berger, R. J., & Heller, H. C. (1979). Sleep and estivation (shallow torpor): Continuous processes of energy conservation: Science Vol 204(4397) Jun 1979, 1098-1100.
  • Wang, L. C., Lee, T. F., & Jourdan, M. L. (1987). Seasonal difference in thermoregulatory responses to opiates in a mammalian hibernator: Pharmacology, Biochemistry and Behavior Vol 26(3) Mar 1987, 565-571.
  • Warren, H. C. (1895). Hibernation and Allied States in Animals: Psychological Review Vol 2(4) Jul 1895, 416.
  • Weekley, B., & Harlow, H. J. (1985). Effects of pharmacological manipulation of the renin-angiotensin system on the hibernation cycle of the 13-lined ground squirrel (Spermophilus tridecemlineatus): Physiology & Behavior Vol 34(1) Jan 1985, 147-149.
  • Weltzin, M. M., Zhao, H. W., Drew, K. L., & Bucci, D. J. (2006). Arousal from hibernation alters contextual learning and memory: Behavioural Brain Research Vol 167(1) Feb 2006, 128-133.
  • Wiklund, C., Vallin, A., Friberg, M., & Jakobsson, S. (2008). Rodent predation on hibernating peacock and small tortoiseshell butterflies: Behavioral Ecology and Sociobiology Vol 62(3) Jan 2008, 379-389.
  • Wilkinson, M., Buchanan, G. D., Jacobson, W., & Younglai, E. V. (1986). Brain opioid receptors in the hibernating bat, Myotis lucifugus: Modification by low temperature and comparison with rat, mouse and hamster: Pharmacology, Biochemistry and Behavior Vol 25(3) Sep 1986, 527-532.
  • Yu, L.-c., & Cai, Y.-p. (1993). Arousal following intra-preoptic area administration of naltrexone, ICI 174864 or nor-BNI in hibernating ground squirrels: Behavioural Brain Research Vol 57(1) Oct 1993, 31-35.

External links[]