Editing Sleep (section)

=== Awakening ===
{{Redirect|Waking up }}
{{Further|Wakefulness|Ascending reticular activating system}}
[[File:1900 The Awakening.jpg|thumb|"The Awakening", an illustration to writing by [[Leo&nbsp;Tolstoy]]
]]
Awakening can mean the end of sleep, or simply a moment to survey the environment and readjust body position before falling back asleep. Sleepers typically awaken soon after the end of a REM phase or sometimes in the middle of REM. Internal [[Circadian clock|circadian indicators]], along with a successful reduction of homeostatic sleep need, typically bring about awakening and the end of the sleep cycle.<ref name=AkerstedtEtAl2002>{{cite journal | vauthors = Akerstedt T, Billiard M, Bonnet M, Ficca G, Garma L, Mariotti M, Salzarulo P, Schulz H | display-authors = 6 | title = Awakening from sleep | journal = Sleep Medicine Reviews | volume = 6 | issue = 4 | pages = 267–86 | date = August 2002 | pmid = 12531132 | doi = 10.1053/smrv.2001.0202 | doi-access = free }}</ref> Awakening involves heightened electrical activation in the brain, beginning with the [[thalamus]] and spreading throughout the [[Cerebral cortex|cortex]].<ref name=AkerstedtEtAl2002 />

On a typical night of sleep, there is not much time that is spent in the waking state. In various sleep studies that have been conducted using the electroencephalography, it has been found that females are awake for 0–1% during their nightly sleep while males are awake for 0–2% during that time. In adults, wakefulness increases, especially in later cycles. One study found 3% awake time in the first ninety-minute sleep cycle, 8% in the second, 10% in the third, 12% in the fourth, and 13–14% in the fifth. Most of this awake time occurred shortly after REM sleep.<ref name=AkerstedtEtAl2002 />

Today, many humans wake up with an [[alarm clock]];<ref name=RonnenbergEtAl2007>{{cite journal | vauthors = Roenneberg T, Kuehnle T, Juda M, Kantermann T, Allebrandt K, Gordijn M, Merrow M | title = Epidemiology of the human circadian clock | journal = Sleep Medicine Reviews | volume = 11 | issue = 6 | pages = 429–38 | date = December 2007 | pmid = 17936039 | doi = 10.1016/j.smrv.2007.07.005 | url = https://pure.rug.nl/ws/files/6712602/2007SleepMedRevRoenneberg.pdf | hdl = 11370/65d6f03a-88cd-405c-a067-4afbc1b9ba9d | s2cid = 11628329 | hdl-access = free }}</ref> however, people can also reliably wake themselves up at a specific time with no need for an alarm.<ref name=AkerstedtEtAl2002 /> Many sleep quite differently on workdays versus days off, a pattern which can lead to chronic circadian desynchronization.<ref name=WaterhouseEtAl2012>{{cite journal | vauthors = Waterhouse J, Fukuda Y, Morita T | title = Daily rhythms of the sleep-wake cycle | journal = Journal of Physiological Anthropology | volume = 31 | issue = 5 | pages = 5 | date = March 2012 | pmid = 22738268 | pmc = 3375033 | doi = 10.1186/1880-6805-31-5 | doi-access = free }}</ref><ref name=RonnenbergEtAl2007 /> Many people regularly look at television and other screens before going to bed, a factor which may exacerbate disruption of the circadian cycle.<ref name="ChangAM" /><ref>{{cite journal | vauthors = Basner M, Dinges DF | title = Dubious bargain: trading sleep for Leno and Letterman | journal = Sleep | volume = 32 | issue = 6 | pages = 747–52 | date = June 2009 | pmid = 19544750 | pmc = 2690561 | doi = 10.1093/sleep/32.6.747 }}</ref> Scientific studies on sleep have shown that sleep stage at awakening is an important factor in amplifying [[sleep inertia]].<ref>{{cite journal | vauthors = Tassi P, Muzet A | title = Sleep inertia | journal = Sleep Medicine Reviews | volume = 4 | issue = 4 | pages = 341–353 | date = August 2000 | pmid = 12531174 | doi = 10.1053/smrv.2000.0098 }}</ref>

Determinants of [[alertness]] after waking up include quantity/quality of the sleep, physical activity the day prior, a carbohydrate-rich breakfast, and a low [[Blood sugar level|blood glucose]] response to it.<ref>{{cite journal |last1=Vallat |first1=Raphael |last2=Berry |first2=Sarah E. |last3=Tsereteli |first3=Neli |last4=Capdevila |first4=Joan |last5=Khatib |first5=Haya Al |last6=Valdes |first6=Ana M. |last7=Delahanty |first7=Linda M. |last8=Drew |first8=David A. |last9=Chan |first9=Andrew T. |last10=Wolf |first10=Jonathan |last11=Franks |first11=Paul W. |last12=Spector |first12=Tim D. |last13=Walker |first13=Matthew P. |title=How people wake up is associated with previous night's sleep together with physical activity and food intake |journal=Nature Communications |date=19 November 2022 |volume=13 |issue=1 |pages=7116 |doi=10.1038/s41467-022-34503-2 |pmid=36402781 |pmc=9675783 |bibcode=2022NatCo..13.7116V |language=en |issn=2041-1723|doi-access=free}}</ref>