Editing Sleep (section)

===Sleep duration and quality===
Sleep duration measures the length of sleep, whereas sleep quality includes factors such as speed in falling asleep and whether sleep is unbroken.<ref>{{cite web | url=https://www.sleepfoundation.org/sleep-hygiene/how-to-determine-poor-quality-sleep | title=How to Determine Poor Sleep Quality | date=17 December 2020 }}</ref><ref>{{cite web | url=https://www.thensf.org/what-is-sleep-quality/ | title=What is Sleep Quality? | date=12 April 2024 }}</ref> Adequate quality sleep is linked with better mood and the abilities to express and quickly process [[emotion]].<ref>{{Cite journal |last1=Lollies |first1=Friederike |last2=Schnatschmidt |first2=Marisa |last3=Bihlmeier |first3=Isabell |last4=Genuneit |first4=Jon |last5=In-Albnon |first5=Tina |last6=Holtmann |first6=Martin |last7=Legenbauer |first7=Tanja |last8=Schlarb |first8=Angelika Anita |date=December 2022 |title=Associations of sleep and emotion regulation processes in childhood and adolescence - a systematic review, report of methodological challenges and future directions |journal=Sleep Science |language=en |volume=15 |issue=4 |pages=490–514 |doi=10.5935/1984-0063.20220082 |pmid=36419813 |issn=1984-0659 |pmc=9670771 }}</ref>

Low quality sleep has been linked with health conditions like [[cardiovascular disease]], [[obesity]], and [[mental illness]]. While poor sleep is common among those with cardiovascular disease, some research indicates that poor sleep can be a contributing cause. Short sleep duration of less than seven hours is correlated with [[coronary heart disease]] and increased risk of death from coronary heart disease. Sleep duration greater than nine hours is also correlated with coronary heart disease, as well as [[stroke]] and cardiovascular events.<ref name="Hale">{{cite journal | vauthors = Hale L, Troxel W, Buysse DJ | title = Sleep Health: An Opportunity for Public Health to Address Health Equity | journal = Annual Review of Public Health | volume = 41 | issue = 1 | pages = 81–99 | date = April 2020 | pmid = 31900098 | pmc = 7944938 | doi = 10.1146/annurev-publhealth-040119-094412 | doi-access = free }}</ref><ref name="Jackson">{{cite journal | vauthors = Jackson CL, Redline S, Emmons KM | title = Sleep as a potential fundamental contributor to disparities in cardiovascular health | journal = Annual Review of Public Health | volume = 36 | issue = 1 | pages = 417–440 | date = March 2015 | pmid = 25785893 | pmc = 4736723 | doi = 10.1146/annurev-publhealth-031914-122838 }}</ref><ref name="Cespedes">{{cite journal | vauthors = Cespedes Feliciano EM, Quante M, Rifas-Shiman SL, Redline S, Oken E, Taveras EM | title = Objective Sleep Characteristics and Cardiometabolic Health in Young Adolescents | journal = Pediatrics | volume = 142 | issue = 1 | pages = e20174085 | date = July 2018 | pmid = 29907703 | pmc = 6260972 | doi = 10.1542/peds.2017-4085 }}</ref><ref name="pmid27647451">{{cite journal | vauthors = St-Onge MP, Grandner MA, Brown D, Conroy MB, Jean-Louis G, Coons M, Bhatt DL | title = Sleep Duration and Quality: Impact on Lifestyle Behaviors and Cardiometabolic Health: A Scientific Statement From the American Heart Association | journal = Circulation | volume = 134 | issue = 18 | pages = e367–e386 | date = November 2016 | pmid = 27647451 | pmc = 5567876 | doi = 10.1161/CIR.0000000000000444 | type = Review }}</ref>

In both children and adults, short sleep duration is associated with an increased risk of obesity, with various studies reporting an increased risk of 45–55%. Other aspects of sleep health have been associated with obesity, including daytime napping, sleep timing, the variability of sleep timing, and low sleep efficiency. However, sleep duration is the most-studied for its impact on obesity.<ref name="Hale"/>

Sleep problems have been frequently viewed as a symptom of mental illness rather than a causative factor. However, a growing body of evidence suggests that they are both a cause and a symptom of mental illness. Insomnia is a significant predictor of [[major depressive disorder]]; a [[meta-analysis]] of 170,000 people showed that insomnia at the beginning of a study period indicated a more than the twofold increased risk for major depressive disorder. Some studies have also indicated correlation between insomnia and [[anxiety]], [[post-traumatic stress disorder]], and [[suicide]]. Sleep disorders can increase the risk of [[psychosis]] and worsen the severity of psychotic episodes.<ref name="Hale"/>

Sleep research also displays [[race and health|differences in race]] and class. Short sleep and poor sleep are observed more frequently in ethnic minorities than in whites in the US. African-Americans report experiencing short durations of sleep five times more often than whites, possibly as a result of social and environmental factors. A study done in the USA suggested that higher rates of sleep apnea (and poorer responses to treatment) are suffered by children in disadvantaged neighborhoods (which, in context, includes a disproportionate effect on children of African-American descent).<ref name="Wang">{{cite journal | vauthors = Wang R, Dong Y, Weng J, Kontos EZ, Chervin RD, Rosen CL, Marcus CL, Redline S | display-authors = 6 | title = Associations among Neighborhood, Race, and Sleep Apnea Severity in Children. A Six-City Analysis | journal = Annals of the American Thoracic Society | volume = 14 | issue = 1 | pages = 76–84 | date = January 2017 | pmid = 27768852 | pmc = 5291481 | doi = 10.1513/AnnalsATS.201609-662OC }}</ref>