Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. During sleep, there is a marked decrease in muscle activity and interactions with the surrounding environment. While sleep differs from wakefulness in terms of the ability to react to stimuli, it still involves active brain patterns, making it more reactive than a coma or disorders of consciousness.[1]
Sleep occurs in repeating periods, during which the body alternates between two distinct modes: REM and non-REM sleep. Although REM stands for "rapid eye movement", this mode of sleep has many other aspects, including virtual paralysis of the body.[2] Dreams are a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep.
During sleep, most of the body's systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems;[3] these are vital processes that maintain mood, memory, and cognitive function, and play a large role in the function of the endocrine and immune systems.[4] The internal circadian clock promotes sleep daily at night, when it is dark. The diverse purposes and mechanisms of sleep are the subject of substantial ongoing research.[5] Sleep is a highly conserved behavior across animal evolution,[6] likely going back hundreds of millions of years.[7]
Humans may suffer from various sleep disorders, including dyssomnias, such as insomnia, hypersomnia, narcolepsy, and sleep apnea; parasomnias, such as sleepwalking and rapid eye movement sleep behavior disorder; bruxism; and circadian rhythm sleep disorders. The use of artificial light has substantially altered humanity's sleep patterns.[8] Common sources of artificial light include outdoor lighting and the screens of electronic devices such as smartphones and televisions, which emit large amounts of blue light, a form of light typically associated with daytime. This disrupts the release of the hormone melatonin needed to regulate the sleep cycle.[9]
- ^ "Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke". www.ninds.nih.gov. Retrieved 15 February 2023.
- ^ Nelson, Ryan (20 June 2021). "The Dichotomy Of Sleep: REM And Non-REM Stages, And Their Impact On Human Health". Quantify Sleep. Retrieved 15 July 2023.
- ^ Krueger JM, Frank MG, Wisor JP, Roy S (August 2016). "Sleep function: Toward elucidating an enigma". Sleep Medicine Reviews. 28: 46–54. doi:10.1016/j.smrv.2015.08.005. ISSN 1087-0792. PMC 4769986. PMID 26447948.
- ^ "Sleep-wake cycle: its physiology and impact on health" (PDF). National Sleep Foundation. 2006. Archived (PDF) from the original on 30 August 2017. Retrieved 24 May 2017.
- ^ Bingham R, Terrence S, Siegel J, Dyken ME, Czeisler C (February 2007). "Waking Up To Sleep" (Several conference videos). The Science Network. Archived from the original on 24 July 2011. Retrieved 25 January 2008.
- ^ Joiner WJ (October 2016). "Unraveling the Evolutionary Determinants of Sleep". Current Biology. 26 (20): R1073–R1087. Bibcode:2016CBio...26R1073J. doi:10.1016/j.cub.2016.08.068. PMC 5120870. PMID 27780049.
- ^ Keene, Alex C & Duboue, Erik R. (12 June 2018). "The origins and evolution of sleep". The Journal of Experimental Biology. 221 (11). doi:10.1242/jeb.159533. PMC 6515771. PMID 29895581. Retrieved 10 January 2023.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Randall DK (19 September 2012). "Book excerpt: How the lightbulb disrupted our sleeping patterns and changed the world". National Post. Archived from the original on 7 April 2019. Retrieved 31 August 2016.
"... the sudden introduction of bright nights during hours when it should be dark threw a wrench into a finely choreographed system of life.
- ^ "How Blue Light Affects Sleep". Sleep Foundation. 4 November 2020. Retrieved 18 November 2021.