Adequate sleep is essential for general healthy functioning. This paper reviews recent research on the effects of chronic sleep restriction on neurobehavioral and physiological functioning and discusses implications for health and lifestyle. Restricting sleep below an individual's optimal time in bed (TIB) can cause a range of neurobehavioral deficits, including lapses of attention, slowed working memory, reduced cognitive throughput, depressed mood, and perseveration of thought. Neurobehavioral deficits accumulate across days of partial sleep loss to levels equivalent to those found after 1 to 3 nights of total sleep loss. Recent experiments reveal that following days of chronic restriction of sleep duration below 7 hours per night, significant daytime cognitive dysfunction accumulates to levels comparable to that found after severe acute total sleep deprivation. Additionally, individual variability in neurobehavioral responses to sleep restriction appears to be stable, suggesting a trait-like (possibly genetic) differential vulnerability or compensatory changes in the neurobiological systems involved in cognition. A causal role for reduced sleep duration in adverse health outcomes remains unclear, but laboratory studies of healthy adults subjected to sleep restriction have found adverse effects on endocrine functions, metabolic and inflammatory responses, suggesting that sleep restriction produces physiological consequences that may be unhealthy. Circadian Rhythms and Sleep Circadian regulation Non-REM sleep Physiological Psychology Sleep Deprivation Sleep Disorders Sleep Deprivation Effects on Decision Making REFERENCES Rechtschaffen A, Bergmann BM, Everson CA, Kushida CA, Gilliland MA. Sleep deprivation in the rat: I. Conceptual issues. Sleep 1989;12:1–4. Google Scholar Rechtschaffen A, Bergmann BM. Sleep deprivation in the rat: an update of the 1989 paper. Sleep 2002;25:18–24. Google Scholar Dinges DF, Chugh DK. Physiologic correlates of sleep deprivation. In: Kinney JM, Tucker HN, eds. Physiology, stress, and malnutrition: Functional correlates, nutritional intervention. New York: Lippincott-Raven; 1997:1–27. The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep 2003;26:117–26. Google Scholar Guilleminault C, Powell NB, Martinez S, et al. Preliminary observations on the effects of sleep time in a sleep restriction paradigm. Sleep Med 2003;4:177–84. Google Scholar Carskadon MA, Roth T. Sleep restriction. In: Monk TH, ed. Sleep, sleepiness and performance. Chichester: John Wiley & Sons; 1991:155–67. Google Scholar Dinges DF, Pack F, Williams K, et al. Comparative utility of instruments for monitoring sleepiness-related performance decrements in the operational environment. J Sleep Res 2004;13:219–27. Google Scholar Dorrian J, Rogers NL, Dinges DF. Psychomotor vigilance performance: neurocognitive assay sensitive to sleep loss. In: Kushida C, ed. Sleep Deprivation. New York: Marcel Dekker; 2005. Google Scholar Dinges DF, Kribbs NB, eds. Performing while sleepy: effects of experimentally induced sleepiness. Winchester, England: John Wiley & Sons; 1991. Google Scholar Kleitman N. Sleep and wakefulness. Second ed. Chicago: University of Chicago Press; 1963. Google Scholar Doran SM, Van Dongen HPA, Dinges DF. Google Scholar Chee MWL, Chuah LYM, Venkatraman V, Chan WY, Philip P, Dinges DF. Functional imaging of working memory following normal sleep and after 24 and 35 h of sleep deprivation: Correlations of fronto-parietal activation with performance. Neuroimage. In press. Dorrian J, Dinges DF. Sleep deprivation and its effects on cognitive performance. Encyclopedia of sleep medicine; Hoboken, NJ: J. Wiley & Sons; 2005. Google Scholar Harrison Y, Horne JA. The impact of sleep deprivation on decision making: A review. J Expl Psychol: Appl 2000;6:236–249. Google Scholar Banks S, Catcheside P, Lack L, Grunstein RR, McEvoy RD. Slow-release caffeine as a countermeasure to driver sleepiness induced by partial sleep deprivation. J Sleep Res 2001;10:203–9. Google Scholar De Valck E, De Groot E, Cluydts R. Effects of slow-release caffeine and a nap on driving simulator performance after partial sleep deprivation. Percept Mot Skills. 2003;96:67–78. Google Scholar Lenne MG, Dwyer F, Triggs TJ, Rajaratnam S, Redman JR. The effects of a nap opportunity in quiet and noisy environments on driving performance. Chronobiol Int 2004;21:991–1001. Google Scholar Macchi MM, Boulos Z, Ranney T, Simmons L, Campbell SS. Effects of an afternoon nap on nighttime alertness and performance in long-haul drivers. Google Scholar Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet 1999;354:1435–9. Google Scholar Tochikubo O, Ikeda A, Miyajima E, Ishii M. Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder. Hypertension 1996;27:1318–24. Google Scholar Kato M, Phillips BG, Sigurdsson G, Narkiewicz K, Pesek CA, Somers VK. Effects of sleep deprivation on neural circulatory control. Hypertension 2000;35:1173–5. Google Scholar Spiegel K, Leproult R, L’Hermite-Baleriaux M, Copinschi G, Penev PD, Van Cauter E. Google Scholar Dinges DF, Douglas SD, Zaugg L, et al. Leukocytosis and natural killer cell function parallel neurobehavioral fatigue induced by 64 hours of sleep deprivation. J Clin Invest 1994;93:1930–9. Google Scholar Shearer WT, Reuben JM, Mullington JM, et al. Soluble TNF alpha receptor 1 and IL-6 plasma levels in humans subjected to the sleep deprivation model of spaceflight. J Allergy Clin Immunol 2001;107:165–70. Google Scholar Spiegel K, Sheridan JF, Van Cauter E. Effect of sleep deprivation on response to immunization. JAMA 2002;288:1471–2. Google Scholar Balachandran DD, Ewing SB, Murray BJ, LeBeau L, Mullington JM. Human host response during chronic partial sleep deprivation.