We need sleep to live.101
Current hypotheses about sleep’s role and function are often based on observing the negative effects of sleep deprivation in humans and animals. When rats are totally deprived of sleep, they die within two to three weeks. They also die if they are deprived of all rapid eye movement (REM) sleep but allowed some non-rapid eye movement (NREM) sleep, although this takes longer — about six weeks.102The cause of death is still in dispute.103
In healthy human volunteers, even one night of total sleep deprivation can decrease cognitive functioning104 105,impair memory106 107 reduce endocrine and metabolic functioning,108 and cause cardiovascular dysfunction.109
After one sleepless night, the effects of sleep loss may be masked by increases in physical and/or mental stimulation. In acute emergencies, a surge of adrenaline can compensate for the lack of sleep. After two or three nights of total sleep deprivation, microsleeps of a few seconds may intrude into wakefulness, causing daytime performance to deteriorate, even if the person is highly motivated to stay awake.110 (Microsleeps are brief sleep episodes that can last for a fraction of a second up to 30 seconds.)
As sleep deprivation continues, microsleeps become longer and more frequent. After about 10 days of total sleep deprivation, electroencephalogram (EEG) recordings can no longer distinguish whether the individual is awake or asleep, even when performing tasks associated with wakefulness, like walking.111
101. Durmer JS, Dinges DF. Neurocognitive consequences of sleep deprivation. Semin Neurol. 2005;25:117-129.
102. Rechtschaffen A. Current perspectives on the function of sleep. Perspect Biol Med. 1998;41:359-390.
103. Benca RM, Kushida CA, Everson CA, et al. Sleep deprivation in the rat: VII. Immune function. Sleep. 1989;12:47-52.
104. Belenky G, Wesenstein NJ, Thorne DR, et al. Patterns of performance degradation and restoration during sleep restriction and subsequent recovery: A sleep dose-response study. J Sleep Res. 2003;12:1-12.
105. Vgontzas AN, Papanicolaou DA, Bixler EO, et al. Circadian interleukin-6 secretion and quantity and depth of sleep. J Clin Endocrinol Metab. 1999;84:2603-2607.
106. Heuer H, Kohlisch O, Klein W. The effects of total sleep deprivation on the generation of random sequences of key-presses, numbers and nouns. Q J Exp Psychol A. 2005;58:275-307.
107. Nilsson JP, Soderstrom M, Karlsson AU, et al. Less effective executive functioning after one night's sleep deprivation. J Sleep Res. 2005;14:1-6.
108. Copinschi G. Metabolic and endocrine effects of sleep deprivation. Essent Psychopharmacol. 2005;6:341-347
109. Smith C. Sleep states and memory processes in humans: procedural versus declarative memory systems. Sleep Med Rev. 2001;5:491-506.
110. Bonnet MH. Acute sleep deprivation. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine. 5th ed. Philadelphia: Elsevier and Saunders; 2011:54-66.
111. Kales A, Tan TL, Kollar EJ, et al. Sleep patterns following 205 hours of sleep deprivation. Psychosom Med. 1970;32:189-200.