Sleep deprivation

===Weight gain ===
{{main|Sleep and weight}}
A lack of sleep can cause an imbalance in several hormones that are critical for weight gain. Sleep deprivation increases the level of ghrelin (hunger hormone) and decreases the level of leptin (fullness hormone), resulting in an increased feeling of hunger and a desire for high-calorie foods.<ref name="VanCauter">{{cite journal | vauthors = Van Cauter E, Spiegel K | title = Sleep as a mediator of the relationship between socioeconomic status and health: a hypothesis | journal = Annals of the New York Academy of Sciences | volume = 896 | issue = 1 | pages = 254–261 | year = 1999 | pmid = 10681902 | doi = 10.1111/j.1749-6632.1999.tb08120.x | bibcode = 1999NYASA.896..254V | s2cid = 36513336 }}</ref><ref name="RatExperiments"/> Sleep loss is also associated with decreased growth hormone and elevated cortisol levels, which are connected to obesity. People who do not get sufficient sleep can also feel sleepy and fatigued during the day and get less exercise. Obesity can cause poor sleep quality as well. Individuals who are overweight or obese can experience obstructive sleep apnea, gastroesophageal reflux disease (GERD), depression, asthma, and osteoarthritis, all of which can disrupt a good night's sleep.<ref>{{Cite web|title=The Link Between Obesity and Sleep Deprivation|url=https://www.sleepfoundation.org/physical-health/obesity-and-sleep|access-date=21 January 2021|website=Sleep Foundation|date=4 December 2020 |language=en}}</ref>

In rats, prolonged, complete sleep deprivation increased both food intake and energy expenditure, with a net effect of weight loss and ultimately death.<ref>{{cite journal | vauthors = Everson CA, Bergmann BM, Rechtschaffen A | title = Sleep deprivation in the rat: III. Total sleep deprivation | journal = Sleep | volume = 12 | issue = 1 | pages = 13–21 | date = February 1989 | pmid = 2928622 | doi = 10.1093/sleep/12.1.13 | doi-access = free }}</ref> This study hypothesizes that the moderate chronic [[sleep debt]] associated with habitual short sleep is associated with increased appetite and energy expenditure, with the equation tipped towards food intake rather than expenditure in societies where high-calorie food is freely available.<ref name="RatExperiments">{{cite journal | vauthors = Taheri S, Lin L, Austin D, Young T, Mignot E | title = Short sleep duration is associated with reduced leptin, elevated ghrelin, and increased body mass index | journal = PLOS Medicine | volume = 1 | issue = 3 | pages = e62 | date = December 2004 | pmid = 15602591 | pmc = 535701 | doi = 10.1371/journal.pmed.0010062 | doi-access = free }}</ref>
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