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The Functions of Sleep

Sleep Disorders Center, Division of Pulmonary and Critical Care, Department of Medicine, University of Maryland, Baltimore, MD 21201

Topical Section: The Function of Sleep

Sleep is a ubiquitous component of animal life including birds and mammals. The exact function of sleep has been one of the mysteries of biology. A considerable number of theories have been put forward to explain the reason(s) for the necessity of sleep. To date, while a great deal is known about what happens when animals sleep, there is no definitive comprehensive explanation as to the reason that sleep is an inevitable part of animal functioning. It is well known that sleep is a homeostatically regulated body process, and that prolonged sleep deprivation is fatal in animals. In this paper, we present some of the theories as to the functions of sleep and provide a review of some hypotheses as to the overall physiologic function of sleep. To better understand the purpose for sleeping, we review the effects of sleep deprivation on physical, neurocognitive and psychic function. A better understanding of the purpose for sleeping will be a great advance in our understanding of the nature of the animal kingdom, including our own.
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Keywords sleep; sleep function; sleep deprivation; sleep theories; sleep restoration

Citation: Samson Z Assefa, Montserrat Diaz-Abad, Emerson M Wickwire, Steven M Scharf. The Functions of Sleep. AIMS Neuroscience, 2015, 2(3): 155-171. doi: 10.3934/Neuroscience.2015.3.155


  • 1. Rechtschaffen A (1971) The control of sleep. In Hynt WA (ed): Human Behavior and its control. Cambridge, MA; Shenkman Publishing Company, Inc.
  • 2. Rechtschaffen (1998) Current perspectives on the function of sleep. Perspect Biol Med 41(3): 359 (32).
  • 3. Destexhe A, Contreras D, Steriade M (1999) Spatiotemporal analysis of local field potentials and unit discharges in cat cerebral cortex during natural wake and sleep states. J Neurosci 19(11):4595-4608.
  • 4. Borbely AA (1982) A two process model of sleep regulation. Hum Neurobiol 1: 195-204.
  • 5. Aristotle (1908) On sleep and sleeplessness; Translated by John Isaac Beare; 2014; Kindle Edition.
  • 6. Piéron H (1912) Le problème Physiologique du Sommeil Paris; Maison Et Cie; Editeurs; Libraires de L'Académie de Médicine
  • 7. Morrison AR (2013) Coming to grips with a “new” state of consciousness: the study of Rapid Eye Movement Sleep in the 1960's. J Hist Neurosci 22: 392-407.    
  • 8. Shepard JW, Biysse DJ, Chesson AL Jr, et al. (2005) History of the development of sleep medicine in the United States. J Clin Sleep Med 1: 61-82.
  • 9. Schmidt MH (2014) The energy allocation function of sleep: A unifying theory of sleep, torpor, and continuous wakefulness. Neurosci Biobehav Rev 47(0): 122-153.
  • 10. Weitzman E D, Nogeire C, Perlow M, et al. (1974) Effects of a prolonged 3-hour sleep-wake cycle on sleep stages, plasma cortisol, growth hormone and body temperature in man. J Clin Endoc Metab 38(6): 1018-1030.
  • 11. Guyon A, Balbo M, Morselli, et al. (2014) Adverse effects of two nights of sleep restriction on the hypothalamic-pituitary-adrenal axis in healthy men. J Clin Endoc Metab 99(8): 2861-2868.
  • 12. Van Cauter E, Plat L (1996) Physiology of growth hormone secretion during sleep. J Pediatr 128(5 Pt 2): S32-37.
  • 13. Van Cauter E, Blackman JD, Roland D, et al. (1991) Modulation of glucose regulation and insulin secretion by circadian rhythmicity and sleep. J Clin Invest 88(3): 934-942.
  • 14. Spiegel K, Luthringer R, Follenius M, et al. (1995) Temporal relationship between prolactin secretion and slow-wave electroencephalic activity during sleep. Sleep 18(7): 543-548.
  • 15. Luboshitzky R, Herer P, Levi, et al. (1999) Relationship between rapid eye movement sleep and testosterone secretion in normal men. J Androlo 20(6): 731-737.
  • 16. Jung CM, Melanson EL, Frydendall EJ, et al. (2011) Energy expenditure during sleep, sleep deprivation and sleep following sleep deprivation in adult humans. J Physiolo 589 (Pt 1): 235-244.
  • 17. Klingenberg L, Sjodin A, Holmback U, et al. (2012) Short sleep duration and its association with energy metabolism. Obesity Reviews: An Official Journal of the International Association for the Study of Obesity 13(7): 565-577.
  • 18. Spiegel K, Tasali E, Penev P, et al. (2004) Brief communication: sleep curtailment in healthy young men is associated with decreased leptin levels, elevated ghrelin levels, and increased hunger and appetite. Ann Int Medi 141(11): 846-850.
  • 19. Spaeth AM, Dinges DF, Goel N (2013) Effects of experimental sleep restriction on weight gain, caloric intake, and meal timing in healthy adults. Sleep 36(7): 981-990.
  • 20. Lange T, Dimitrov S, Bollinger, et al. (2011) Sleep after vaccination boosts immunological memory. J Immunol (Baltimore, Md.: 1950), 187(1): 283-290.
  • 21. Irwin MR, Wang M, Campomayor CO, et al. (2006) Sleep deprivation and activation of morning levels of cellular and genomic markers of inflammation. Arch Int Med 166(16): 1756-1762.
  • 22. Tamakoshi A, Ohno Y, JACC Study Group (2004) Self-reported sleep duration as a predictor of all-cause mortality: Results from the JACC study, japan. Sleep 27(1): 51-54.
  • 23. Rod NH, Kumari M, Lange T, et al. (2014) The joint effect of sleep duration and disturbed sleep on cause-specific mortality: Results from the whitehall II cohort study. PloS One 9(4): e91965.
  • 24. Altman NG, Izci-Balserak B, Schopfer E, et al. (2012) Sleep duration versus sleep insufficiency as predictors of cardiometabolic health outcomes. Sleep Med 13(10): 1261-1270.
  • 25. Van Leeuwen WM, Lehto M, Karisola P, et al. (2009) Sleep restriction increases the risk of developing cardiovascular diseases by augmenting proinflammatory responses through IL-17 and CRP. PloS One 4(2): e4589.
  • 26. Spiegel K, Leproult R, Van Cauter E (1999) Impact of sleep debt on metabolic and endocrine function. Lancet 354(9188): 1435-1439.
  • 27. Tochikubo O, Ikeda A, Miyajima E, et al. (1996) Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder. Hypertension 27(6), 1318-1324.
  • 28. Banks S, Dinges DF (2007) Behavioral and physiological consequences of sleep restriction. J Clin Sleep Med: JCSM: Official Publication of the American Academy of Sleep Medicine 3(5): 519-528.
  • 29. Walker MP, Brakefield T, Morgan A, et al. (2002) Practice with sleep makes perfect: Sleep-dependent motor skill learning. Neuron 35(1): 205-211.
  • 30. Nishida M, Walker MP (2007) Daytime naps, motor memory consolidation and regionally specific sleep spindles. PloS One 2(4): e341.
  • 31. Gais S, Molle M, Helms K, et al. (2002) Learning-dependent increases in sleep spindle density. J Neurosci: The Official Journal of the Society for Neuroscience 22(15): 6830-6834.
  • 32. Marshall L, Helgadottir H, Molle M, et al. (2006) Boosting slow oscillations during sleep potentiates memory. Nature 444(7119): 610-613.
  • 33. Astill RG, Piantoni G, Raymann RJ, et al. (2014) Sleep spindle and slow wave frequency reflect motor skill performance in primary school-age children. Frontiers Hum Neurosci 8: 910.
  • 34. De Koninck J, Lorrain D, Christ, et al. (1989) Intensive language learning and increases in rapid eye movement sleep: Evidence of a performance factor. Int J Psychophysiol: Official Journal of the International Organization of Psychophysiology 8(1): 43-47.
  • 35. Abel T, Havekes R, Saletin, et al. (2013) Sleep, plasticity and memory from molecules to whole-brain networks. Curr Biolo: CB 23(17): R774-788.
  • 36. Walker MP (2009) The Year in Cognitive Neuroscience. Ann NY Acad Sci 1156: 168-197.    
  • 37. Goldstein AN, Walker MP (2014) The role of sleep in emotional brain function. Ann Rev Clin Psycholo 10: 679-708.
  • 38. Lim J, Dinges D F (2010) A meta-analysis of the impact of short-term sleep deprivation on cognitive variables. Psycholo Bulletin 136(3): 375-389.
  • 39. Belenky G, Wesensten NJ, Thorne DR, et al. (2003) Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: A sleep dose-response study. J Sleep Res 12(1): 1-12.
  • 40. Dinges D, Powell J (1985) Microcomputer analyses of performance on a portable, simple visual RT task during sustained operations. Behav Res Method Instrum Comput 17(6): 652-655.
  • 41. Van Dongen HP, Maislin G, Mullington JM, et al. (2003) The cumulative cost of additional wakefulness: Dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep 26(2): 117-126.
  • 42. Rupp TL, Wesensten NJ, Bliese PD, et al. (2009) Banking sleep: Realization of benefits during subsequent sleep restriction and recovery. Sleep 32(3): 311-321.
  • 43. Meddis R (1975) On the function of sleep. Animal Behav 23: 676-691.    
  • 44. Webb W (1974) Sleep as an adaptive response. Perceptual Motor Skills 38: 1023-1027.    
  • 45. Webb WB (1979) Theories of sleep functions and some clinical implications. The Functions of Sleep: 19-35.
  • 46. Siegel JM (2009) Sleep viewed as a state of adaptive inactivity. Nat Rev Neurosci 10: 747-753
  • 47. Berger RJ, Phillips NH (1993) Sleep and energy conservation. Physiolo 8: 276-281.
  • 48. Berger RJ, Phillips NH (1995) Energy conservation and sleep. Behav Brain Res 69(1-2): 65-73.
  • 49. Adam K (1980) Sleep as a restorative process and a theory to explain why. Prog Brain Res 53: 289-305.    
  • 50. Oswald I (1980) Sleep as restorative process: Human clues. Prog Brain Res 53: 279-288.
  • 51. Clugston GA, Garlick P J (1982) The response of protein and energy metabolism to food intake in lean and obese man. Hum Nutr: Clin Nutr 36(1): 57-70.
  • 52. Karnovsky M L, Reich P, Anchors JM, et al (1983) Changes in brain glycogen during slow-wave sleep in the rat. J Neurochem 41(5): 1498-1501.
  • 53. Benington JH, Heller HC (1995) Restoration of brain energy metabolism as the function of sleep. Prog Neurobiolo 45(4): 347-360.
  • 54. Benington JH (2000) Sleep homeostasis and the function of sleep. Sleep 23(7): 959-966.
  • 55. Reimund E (1994) The free radical flux theory of sleep. Med Hypotheses 43(4): 231-233.
  • 56. Siegel JM (2005) Clues to the functions of mammalian sleep. Nature 437(7063): 1264-1271.
  • 57. Xie L, Kang H, Xu Q, et al. (2013) Sleep drives metabolite clearance from the adult brain. Science (New York, N.Y.) 342(6156): 373-377.
  • 58. Moruzzi G (1966) Functional significance of sleep for brain mechanisms. In: Eccles JC, ed. Brain and conscious experience. Berlin: Springer-Verlag: 345-388.
  • 59. Moruzzi G (1972) The sleep-waking cycle. Ergeb Physiol 64: 1-165
  • 60. Krueger JM, Obal F (1993) A neuronal group theory of sleep function. J Sleep Res 2(2): 63-69.
  • 61. Kavanau JL (1996) Memory, sleep, and dynamic stabilization of neural circuitry: evolutionary perspectives. Neurosci Biobehav Rev 20: 289-311.
  • 62. Kavanau JL (1997a) Memory, sleep and the evolution of mechanisms of synaptic efficacy maintenance. Neurosci 79: 7-44.
  • 63. Kavanau JL (1997b) Origin and evolution of sleep: roles of vision and endothermy. Brain Res Bulletin 42: 245-264.
  • 64. Kavanau JL (1994) Sleep and dynamic stabilization of neural circuitry: A review and synthesis. Behav Brain Res 63(2): 111-126.
  • 65. Jouvet M (1975) The function of dreaming: a neurophysiologist's point of view. In: Gazzaniga, M.S., Blakemore, C. (Eds.), Handbook of Psychobiology. Academic Press, Inc., New York, pp. 499-527.
  • 66. Crick F, Mitchison G (1983) The function of dream sleep. Nature 304(5922): 111-114.


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Copyright Info: 2015, Samson Z Assefa, et al., licensee AIMS Press. This is an open access article distributed under the terms of the Creative Commons Attribution Licese (http://creativecommons.org/licenses/by/4.0)

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