How much sleep do adults need for good health?
Short answer
Lowest risk at about 7 hours.
In large population studies, death risk was lowest at about 7 hours, and diabetes risk at 7 to 8 hours. Shorter and longer sleep were both linked to more risk. These are links, not proof.
This page says what the research shows. It does not say whether you should change how long you sleep.
Where the evidence stands
Each dot is one on-topic paper. Steps near the top answer the question more directly. Select a dot to see the study.
↑ Stronger evidence
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Trials in people: death and chronic disease
Trials that measured death, heart disease and other health outcomes directly.
0Not done yet. This is the step that would answer the question.
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Trials in people: other measures
Trials that measured other health or performance measures.
1 -
Trials in people: lab tests or safety
Trials that measured lab tests, side effects or safety.
0None among the papers we read.
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Population studies
Studies that followed or surveyed groups of people. They show links, not causes.
11 -
Blood levels and genes
Studies that link blood levels or genes to health.
1
↓ Weaker evidence
- Points to benefit
- Mixed
- No difference
- No direction
- Points to harm
Not on the ladder: 4 reviews of many studies (shown below), 5 opinion or narrative papers. Counts are papers, not people. Some studies appear in more than one paper.
See every studyWhat we found
- Across 153 studies of 5,172,710 people, short sleepers had 1.12 times the death risk of normal sleepers, and higher diabetes (1.37) and obesity (1.38) risk. Itani 2017
- Across 137 studies of 5,134,036 people, long sleepers had 1.39 times the death risk of normal sleepers, and higher stroke (1.46) and diabetes (1.26) risk. Jike 2018
- Death risk was lowest at 7 hours in two cohorts: 322 721 adults in Japan, China, Singapore and Korea, and 25,430 adults in Sweden. Svensson 2021, Åkerstedt 2022
- Genetic studies fit short sleep as a possible cause of heart attack, but found long sleep unlikely to cause most heart diseases. Daghlas 2019, Ai 2021
What the research says
Death risk is lowest near 7 hours
In 322 721 adults in Japan, China, Singapore and Korea, 7 hours was the low point for death from all causes and from heart disease. Sleeping 10 hours or more carried the highest risk: 1.34 times the risk for men and 1.48 times for women.
In 25,430 Swedish adults, risk was lowest at 7 hours but low from 5 to 8 hours. Under 5 hours carried 1.24 times the risk, and 9 hours or more 1.30 times. This U-shape showed only in people over 60.3 years.
Studies: Svensson 2021, Åkerstedt 2022
Short sleep and heart disease: genetic support
In 461,347 UK adults, compared with 6 to 9 hours, short sleepers (under 6 hours) had a 20% higher heart attack risk and long sleepers (over 9 hours) 34% higher. A genetic analysis was consistent with short sleep causing heart attacks.
A genetic study of 404 044 UK adults linked genes for short sleep to 5 of 12 heart diseases, including heart attack. Genes for long sleep were not linked to any. In Chinese adults aged 45 and older, 6 to 8 hours went with the lowest heart disease risk.
Studies: Daghlas 2019, Ai 2021, He 2025
Diabetes and weight follow similar patterns
A pooled review found diabetes risk lowest at 7 to 8 hours: under 7 hours carried 1.18 times the odds, and over 8 hours 1.13 times. Large pooled reviews also linked short sleep (1.38) and, more weakly, long sleep (1.08) to obesity.
In 27,473 adults in Taiwan, short sleep went with 21% higher odds of obesity. In Spanish teenagers, sleeping under 7 hours went with more overweight than 8 to 10 hours. These studies observe people; they do not test changing sleep.
Studies: Liu 2025, Itani 2017, Jike 2018, Lin 2025, Martínez-Gómez 2023
Long sleep and dementia links are less certain
Genes for long sleep were not linked to any of 12 heart diseases. Among 1,360 Chinese adults with diabetes, sleeping over 9 hours went with lower heart disease odds (0.36 times), the opposite of most studies here.
In UK Biobank, short and long sleep links with digestive cancer death disappeared after adjusting for smoking, type 2 diabetes and body mass index. Sleep measures were linked to dementia, but links weakened after adjusting for heart risk factors and were absent in genetic analysis for Alzheimer disease.
Only one small trial changed sleep
In a trial of 80 adults with overweight who slept under 6.5 hours, sleep counseling added about 1.2 hours of sleep a night. Food intake fell by 270 kcal a day compared with the control group, and weight went down.
In 195 adults with obesity after diet weight loss, short sleepers (under 6 hours) regained 5.3 kg over a year. Sleep was measured, not assigned, so this is a link. No trial here tested death or disease.
Studies: Tasali 2022, Bogh 2023
What reviews of many studies found
Reviews pool or sum up earlier studies. They are not on the ladder, because they repeat studies already counted there.
Systematic review · Li 2022
Gathered 69 meta-analyses. Each hour less among short sleepers was linked to 3-11% higher risk of death, heart disease, stroke and diabetes; each hour more among long sleepers to 7-17% higher risk of similar conditions.
Pooled review (meta-analysis) · Itani 2017
Pooled 153 studies with 5,172,710 people. Short sleep was linked to higher risk of death (RR 1.12), diabetes, high blood pressure, heart disease and obesity. Death risk rose in a straight line below six hours.
Pooled review (meta-analysis) · Jike 2018
Pooled 137 studies with 5,134,036 people. Long sleep was linked to higher risk of death (RR 1.39), diabetes, heart disease, stroke and obesity, but not high blood pressure. Authors ask whether the link is causal.
Pooled review (meta-analysis) · Liu 2025
Pooled observational studies (number not given). Under 7 hours (OR 1.18) and over 8 hours (OR 1.13) were both linked to type 2 diabetes, a U-shape with lowest risk at 7 to 8 hours.
How the research grew
The papers we read span 2008 to 2025. 8 of the 22 on-topic papers came out in 2024 to 2026. The earliest trial in people here is from 2022.
- 2008
- 2016
- 2017
- 2018
- 2019
- 2021
- 2022
- 2023
- 2024
- 2025
Each dot is one on-topic paper, colored by what it found. Rings mark key papers:
- 2008. 2008 review ties short sleep to obesity rise. Van Cauter 2008
- 2017. Largest pooled review: short sleep, 5,172,710 people. Itani 2017
- 2018. Companion pooled review links long sleep too. Jike 2018
- 2019. Genetic analysis fits short sleep causing heart attacks. Daghlas 2019
- 2022. Trial: extending sleep cut food intake. Tasali 2022
Who was studied
Who took part, and how many. The largest trial here had 80 people; the largest population study had 502,383.
- Trials in people
- Population, blood and gene studies
- People in the study, log scale1101001,00010,000100,0001,000,000
- Points to benefit
- Mixed
- No difference
- No direction
- Points to harm
Bars use a log scale: each step is ten times more people. Reviews, animal studies and papers with no count in the abstract are not shown.
Who funds this research
One trial paper (35129580) changed sleep; it reported no conflicts and NIH funding. One cohort (34477853) has an author paid by many drug companies, stated as outside the work. Company ties did not change the confidence.
- No stake declared 1
- Tasali 2022No stake declared
Funding rule. A stake is always shown. Confidence is lowered only when every supporting study comes from a party with a stake. "No disclosure in PubMed" means the PubMed record has no conflict-of-interest statement. It does not mean there is no conflict.
All 22 on-topic papers
Each paper shows what it tested, what it found, and who has a stake. Every paper also has its own page that explains how much it counts and how it fits. See every study as a list.
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Effect of Sleep Extension on Objectively Assessed Energy Intake Among Adults With Overweight in Real-life Settings: A Randomized Clinical Trial.
80 people · adults aged 21 to 40 with overweight who slept under 6.5 hours a night
TestedCounseling to sleep up to 8.5 hours in bed, vs keeping usual sleep
Sleep rose by about 1.2 hours a night. Food intake fell by -270 kcal/d (95% CI, -393 to -147 kcal/d) vs control, giving weight reduction in the sleep extension group.
Points to benefitNo stake declaredAbstract onlyNo conflicts reported; funded by NIH institutes.
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Habitual sleep duration, healthy eating, and digestive system cancer mortality.
406,584 people · UK Biobank adults aged 38 to 73, followed a median 12.6 years
TestedShort (6 h or less) and long (9 h or more) sleep vs 7-8 h, then deaths from digestive cancers
Short sleep (1.09; 1.01-1.18) and long sleep (1.14; 1.03-1.27) were both linked to higher death from digestive cancer. Adjusting for smoking, diabetes and BMI removed the links.
MixedNo stake declaredAbstract onlyNo competing interests declared; funded by cancer and Novo Nordisk foundations.
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Sleep duration and cardiovascular disease risk in type 2 diabetes: A prospective cohort study.
1,360 people · Chinese adults with type 2 diabetes in a national aging study
TestedSleep hours (average 6.45) and long sleep over 9 h vs shorter, then new heart disease, stroke or heart failure
Each extra hour of sleep was tied to lower heart disease risk (OR: 0.92, 95% CI: 0.86-0.99). Sleep over 9 h had OR: 0.36 (95% CI: 0.15-0.85) versus shorter sleep.
Points to benefitNo stake declaredAbstract onlyNo conflicts of interest declared.
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Interactive effects of sleep duration and dietary patterns on obesity moderated by age.
27,473 people · adults in Taiwan from a health check-up program
TestedShort sleep vs adequate sleep, with four diet patterns, and obesity
Short sleep was linked to 21% higher odds of obesity than adequate sleep (OR 1.21; 95% CI, 1.15-1.29). Younger adults with too little sleep had higher odds than older adults.
Points to benefitNo stake declaredAbstract onlyNo competing interests declared.
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The Relationship Between Sleep Duration and Cardiovascular Disease: A Prospective Cohort Study Based on Charls.
13,078 people · Chinese adults aged 45 and over in a national aging study
TestedSleep hours (under 5 h up to 8 h) and whether people had heart disease, across three survey waves
Sleep under 5 hours was linked to higher heart disease risk, and 6 to 8 hours to the lowest risk. Each extra hour of sleep went with about 9% lower odds of CVD.
Points to benefitNo stake declaredAbstract onlyNo competing interests declared.
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Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study.
60,977 people · UK Biobank adults, average age 62.8, wearing a movement sensor
TestedHow regular sleep and wake times were vs how long people slept, and deaths over about 6 years
Higher sleep regularity was linked to 20%-48% lower risk of death from any cause. It predicted death better than sleep duration did. No duration-specific hours are in the abstract.
No differenceNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Sleep Characteristics and Risk of Stroke and Dementia: An Observational and Mendelian Randomization Study.
502,383 people · UK Biobank adults, average age 56.5
TestedSelf-reported sleep duration, insomnia, napping, snoring and others vs stroke and dementia
Almost all sleep measures were linked to dementia risk (all p < 0.001, except insomnia), but links weakened after adjusting for heart risk factors. Genetic analysis found no link to dementia. Duration-specific numbers are not in the abstract.
No differenceNo stake declaredAbstract onlyThe authors report no relevant disclosures.
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Insufficient sleep predicts poor weight loss maintenance after 1 year.
195 people · adults with obesity who lost weight on a low-calorie diet
TestedSleep under 6 h a night vs 6 h or more, tracked over 1 year of weight maintenance
After a 13.1 kg weight loss, short sleepers regained 5.3 kg (p = .0008) and lost less body fat (p = .007) than normal sleepers over 1 year.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed; trial also tested liraglutide, a drug.
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Population study: followed a groupMartínez-Gómez et al., 2023European journal of preventive cardiology · PubMed
Sleep duration and its association with adiposity markers in adolescence: a cross-sectional and longitudinal study.
1,216 people · Spanish adolescents followed at ages 12, 14 and 16
TestedSleep under 7 h and 7 to under 8 h compared with 8 to 10 h, measured by 7-day wrist sensor
Compared with 8-10 h sleepers, those under 7 h had overweight or obesity ratios of 1.30 at 12 years, 1.93 at 14 and 1.32 at 16. Those never meeting sleep advice had about 5 times more.
Points to benefitNo stake declaredAbstract onlyNo conflict of interest declared.
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Sleep duration and mortality, influence of age, retirement, and occupational group.
25,430 people · Swedish adults, working and retired, in a national cohort
TestedSleep hours (under 5 h, 5 to 8 h, 9 h or more) compared with 7 h, then deaths
Death risk was U-shaped: HR 1.24 (95% CI 1.10, 1.39) under 5 h and HR 1.30 (95% CI 1.12, 1.51) at 9 h or more. The lowest risk was at 7 h, with low risk across 5 to 8 h, and the U-shape held only for people over 60.3.
MixedNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Association of Sleep Duration With All- and Major-Cause Mortality Among Adults in Japan, China, Singapore, and Korea.
322,721 people · adults in 9 Asian cohorts, average age 54.5, followed about 14 years
TestedSleep hours compared with 7 hours, then deaths
Seven hours was the low point for death from all causes, heart disease and other causes. All-cause death was J-shaped, highest at 10 h or more for men (HR, 1.34; 95% CI, 1.26-1.44) and women (HR, 1.48; 95% CI, 1.36-1.61).
MixedCompany stakeAbstract onlyOne author reports personal fees from many drug companies and grants from several, stated as outside this work.
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Population study: followed a groupDaghlas et al., 2019Journal of the American College of Cardiology · PubMed
Sleep Duration and Myocardial Infarction.
461,347 people · UK Biobank adults free of heart disease, plus genetic data
TestedShort (under 6 h) and long (over 9 h) sleep vs 6 to 9 h, then heart attacks
Compared with 6 to 9 h, short sleepers had a 20% higher heart attack risk (HR: 1.20; 95% CI: 1.07 to 1.33) and long sleepers 34% higher (HR: 1.34; 95% CI: 1.13 to 1.58). Genetic analysis fit a causal effect of short sleep.
MixedNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Causal associations of short and long sleep durations with 12 cardiovascular diseases: linear and nonlinear Mendelian randomization analyses in UK Biobank.
404,044 people · white British adults in UK Biobank
TestedGenes linked to sleep length, short sleep (6 h or less) and long sleep (9 h or more), used to test effects on 12 heart diseases
Genes for short sleep raised risk of high blood pressure, blood clots in lung, coronary artery disease, heart attack and chronic heart disease (P < 0.001). Genes for long sleep were not linked to any of the 12.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Sleep features and the risk of type 2 diabetes mellitus: a systematic review and meta-analysis.
adults in observational studies of type 2 diabetes
TestedNight sleep under 7 h or over 8 h compared with 7 to 8 h; also sleep quality, evening type and naps
Sleep under 7 h (OR = 1.18; 95% CI = 1.13, 1.23) or over 8 h (OR = 1.13; 95% CI = 1.09, 1.18) raised diabetes risk. Lowest risk was at 7 to 8 h, a U-shape.
MixedNo stake declaredAbstract onlyNo competing interests declared.
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Sleep duration and health outcomes: an umbrella review.
69 studies · adults in 69 meta-analyses of sleep duration and health
TestedShort and long sleep compared with normal sleep; per 1-hour change in sleep per 24 hours
A 1-h reduction per 24 hours among short sleepers was linked to 3-11% higher risk of all-cause death, heart disease, stroke and type 2 diabetes. A 1-h increase in long sleepers was linked to 7-17% higher risk of stroke death, heart disease, stroke and diabetes.
MixedNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Long sleep duration and health outcomes: A systematic review, meta-analysis and meta-regression.
137 studies, 5,134,036 people · adults in 137 long-term follow-up studies
TestedLong sleepers compared with normal sleepers
Long sleep was linked to higher risk of death (RR, 1.39; 95% CI, 1.31-1.47), diabetes (1.26), heart disease (1.25), stroke (1.46) and obesity (1.08). It was not linked to high blood pressure (1.01).
Points to harmNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Short sleep duration and health outcomes: a systematic review, meta-analysis, and meta-regression.
153 studies, 5,172,710 people · adults in 153 long-term follow-up studies
TestedShort sleepers compared with normal sleepers
Short sleep was linked to higher risk of death (RR, 1.12; 95% CI, 1.08-1.16), diabetes (1.37), heart disease (1.16), coronary heart disease (1.26) and obesity (1.38). Death risk rose linearly below six hours.
Points to benefitNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Insomnia, Short Sleep, and Their Treatments: Review of Their Associations with Weight.
adults in studies reviewed on insomnia, short sleep and weight
TestedReviews links of insomnia and short sleep with weight gain, and effects of sleep treatments on weight
Short sleep is associated with weight gain, but links between insomnia, short sleep and obesity are inconsistent. More prospective trials are needed.
No weight on the ladderNo stake declaredAbstract onlyNo competing interests declared.
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The links between sleep duration, obesity and type 2 diabetes mellitus.
adults and others in studies reviewed on sleep, obesity and type 2 diabetes
TestedReviews experiments with sleep loss and cohort studies of short sleep
Cohort studies established short sleep as a risk factor for obesity and type 2 diabetes. Small studies tied short sleep to less weight loss after lifestyle change or bariatric surgery.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Sleep and diabetes.
people in studies reviewed on sleep and type 2 diabetes
TestedReviews abnormal sleep length (short and long) and sleep apnea vs diabetes
Large cohorts support a link between abnormal sleep duration, both short and long, and type 2 diabetes. The author notes big methods limits that block firm conclusions.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Insomnia and obesity.
adults in studies reviewed on short sleep, insomnia and obesity
TestedReviews studies of short sleep and overweight, and of people with insomnia
Studies show both positive and negative links between short sleep and overweight. The author says the evidence that sleep duration causes obesity is insufficient.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
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Sleep and the epidemic of obesity in children and adults.
children and adults in lab and population studies reviewed
TestedReviews lab sleep cuts in young adults and population studies of short sleep and weight
The review says short sleep is tied to higher body mass index, and to weight gain and obesity in children and young adults. Lab sleep loss shifted hunger and blood sugar hormones.
No weight on the ladderNo disclosure in PubMedAbstract onlyNo disclosure in PubMed.
32 papers we read and set aside as off topic
- Yuan et al., 2023. Epidemiology of sarcopenia: Prevalence, risk factors, and consequences. (systematic review)
- Irwin et al., 2016. Sleep Disturbance, Sleep Duration, and Inflammation: A Systematic Review and Meta-Analysis of Cohort Studies and Experimental Sleep Deprivation. (pooled review (meta-analysis))
- de Souza et al., 2025. Sleep quality and duration and frailty in older adults: a systematic review. (systematic review)
- Peng et al., 2024. Incidence and factors influencing delayed onset of lactation: a systematic review and meta-analysis. (pooled review (meta-analysis))
- Lu et al., 2021. Sleep disturbances during pregnancy and adverse maternal and fetal outcomes: A systematic review and meta-analysis. (pooled review (meta-analysis))
- Simonson et al., 2024. Multidimensional sleep health and diabetic retinopathy: Systematic review and meta-analysis. (pooled review (meta-analysis))
- Khalid et al., 2024. Effects of magnesium and potassium supplementation on insomnia and sleep hormones in patients with diabetes mellitus. (randomized trial)
- Riemersma-van der Lek et al., 2008. Effect of bright light and melatonin on cognitive and noncognitive function in elderly residents of group care facilities: a randomized controlled trial. (randomized trial)
- Duffy et al., 2022. High dose melatonin increases sleep duration during nighttime and daytime sleep episodes in older adults. (randomized trial)
- Pavlou et al., 2024. Effect of Time-Restricted Eating on Sleep in Type 2 Diabetes. (randomized trial)
- Zuraikat et al., 2024. Chronic Insufficient Sleep in Women Impairs Insulin Sensitivity Independent of Adiposity Changes: Results of a Randomized Trial. (randomized trial)
- Duan et al., 2025. Effects of time-restricted eating on actigraphy-derived sleep parameters: post hoc analysis of a randomized, isocaloric feeding study. (randomized trial)
- Narvaez et al., 2025. Reduced sleep irregularity does not impact peripheral vascular function before or following total sleep deprivation. (randomized trial)
- Facer-Childs et al., 2019. Resetting the late timing of 'night owls' has a positive impact on mental health and performance. (randomized trial)
- Wilms et al., 2019. Sleep Loss Disrupts Morning-to-Evening Differences in Human White Adipose Tissue Transcriptome. (randomized trial)
- Roberge et al., 2019. Lifestyle Habits, Dietary Factors, and the Metabolically Unhealthy Obese Phenotype in Youth. (population study: followed a group)
- St-Laurent et al., 2025. An interdisciplinary intervention improves lifestyle behaviours in women living with obesity and subfertility: A secondary analysis of a randomized controlled trial. (randomized trial)
- Guerlich et al., 2022. Sleep duration and problem behaviour in 8-year-old children in the Childhood Obesity Project. (population study: followed a group)
- Twedt et al., 2023. Sleep intervention and glycemic control in gestational diabetes mellitus: a feasibility study. (randomized trial)
- Chan, 2024. Effects of sleep deprivation on food-related Pavlovian-instrumental transfer: a randomized crossover experiment. (randomized trial)
- Xin et al., 2022. Impact of chronic sleep restriction on sleep continuity, sleep structure, and neurobehavioral performance. (trial, not randomized)
- Stager et al., 2026. Adolescent sleep restriction, macronutrient consumption, and self-reported hunger: A randomized clinical trial. (randomized trial)
- Balcan et al., 2025. Characteristics of short REM sleepers and long-term CPAP use in the RICCADSA cohort. (population study: followed a group)
- Kuo et al., 2023. Predictors of Abnormal Sleep Duration in Older Adults With Hip Fracture and Diabetes. (population study: followed a group)
- Ezpeleta et al., 2023. Alternate-Day Fasting Combined with Exercise: Effect on Sleep in Adults with Obesity and NAFLD. (randomized trial)
- Kanki et al., 2023. Poor sleep and shift work associate with increased blood pressure and inflammation in UK Biobank participants. (population study: followed a group)
- Huang, 2025. Sleep Irregularity, Circadian Disruption, and Cardiometabolic Disease Risk. (opinion or narrative review)
- Dong et al., 2022. Association between sleep duration and depression in US adults: A cross-sectional study. (population study: one-time survey)
- Chen et al., 2025. Association of Sleep Duration With Incident Carotid Plaque: A Prospective Cohort Study. (population study: followed a group)
- Sonti et al., 2022. Leveraging genetic discoveries for sleep to determine causal relationships with common complex traits. (opinion or narrative review)
- Wannamethee, 2024. Napping and Obesity in Adults - What do we Know? (opinion or narrative review)
- Zhang et al., 2024. Insomnia and sleep duration for kidney function: Mendelian randomization study. (gene study (mendelian randomization))
Words on this page
- Hazard ratio (HR)
- Compares how often something happened in two groups over time. 1 means no difference. 0.80 means 20% lower risk; 1.20 means 20% higher.
- Relative risk (RR)
- Compares the risk in two groups. 1 means no difference. 0.85 means 15% lower risk.
- Odds ratio (OR)
- Another way to compare two groups. 1 means no difference. Below 1 means lower odds, above 1 higher odds.
- 95% CI (confidence interval)
- The range where the true result likely lies. If the range includes no effect (1 for ratios, 0 for differences), the result is not clear.
- p-value (p =)
- How likely a result this large would be by chance if there were no real effect. Below 0.05 is usually called a clear result.
- Pooled review (meta-analysis)
- A study that combines the results of many earlier studies to get one overall answer.
- Cohort study
- A study that follows a large group of people over years. It shows links, not causes.
- Gene study (Mendelian randomization)
- A study that uses natural gene differences between people as a kind of experiment.
How the short answer is set
Fixed rules turn the studies into the short answer, so the same studies always give the same answer. The rules start from GRADE, a standard system for rating evidence, in plain language.
| Confidence | What it means |
|---|---|
| High | We are confident the answer is right. |
| Moderate | The answer is probably right, but it could change. |
| Low (this page) | The answer may well change. |
| Very low | Any answer is very uncertain. |
| Not tested in people | Only cell or animal studies exist. |
Why low here
- Evidence on death and disease comes only from population studies, which show links.
- Short-sleep links are consistent, and genetic studies point to heart harm.
- Long-sleep results disagree: genetic studies found no heart disease link.
- The one trial that changed sleep was small and measured food intake.
Hard limit used. No trial changed sleep and then measured death, heart disease, diabetes or dementia, so these hours are links from population studies, not proof that changing sleep changes risk.
How this page was made
Label
- Search
- PubMed, Nov 14, 2026. Searches written by Claude Opus 5.5; papers ranked by PubMed
- First read of all 54 papers
- Claude Sonnet
- Independent second read
- Claude Haiku
- Disagreements settled by
- Claude Opus 5.5
- Page text written by
- Claude Opus 5.5
- Charts
- Drawn by code from the study records
- Source check by a person
- Not yet. Required before search engines may list this page.
- Expert review
- No
- Papers read in full
- 0 of 54; all from PubMed abstracts
- Method
- v0.2, created Nov 14, 2026
Search. We ran four PubMed searches for sleep duration and death, heart disease and other health outcomes: pooled and systematic reviews since 2012 (10 of 204), trials in people (22 of 227), population studies (22 of 2,177). The first number is how many papers we read; the second is how many PubMed found. We took the ones PubMed ranks as most relevant. See the full PubMed search. Of the 54 papers read, 22 were on topic.
Limits. Digestery reads at most about 60 papers per question, so large fields are sampled, not covered in full. Abstracts can leave out key details, such as side effects and funding.
Review queue
These items wait for a person. Search engines are asked not to list the page until the first one is done.
- OpenThe short answer is new. It waits for a source check by a person.
- OpenItani 2017 and Jike 2018 are companion meta-analyses; they and umbrella review Li 2022 likely share cohorts. Check overlap.
- OpenUK Biobank feeds Daghlas 2019, Ai 2021, Guo 2024, Nôga 2025 and Windred 2024; these results are not independent.
- OpenHe 2025 and Jin 2025 both use the CHARLS study; participants may overlap.
- OpenBogh 2023 is a sleep analysis inside a liraglutide drug trial; no COI or funding in PubMed record. Check the funder.
- OpenSvensson 2021 coded company stake for one author's drug-company fees stated outside the work; confirm this should count.
- OpenNôga 2025 partly funded by Novo Nordisk Fonden; reads disagreed on stake; kept none (foundation, no competing interests declared).
- OpenMartínez-Gómez 2023 studies teenagers, not adults; kept relevant but indirect for an adult question.
- OpenHe 2025: n is the 2011 wave (13,078) of three; analysis looks partly cross-sectional despite cohort label.
- OpenJin 2025 links sleep over 9 hours to lower heart disease odds in diabetes, unlike other studies; few long sleepers.
- OpenReads disagreed on relevance of Simonson 2024 (diabetic eye disease), Lu 2021 (pregnancy), Wannamethee 2024 (naps), Sonti 2022 (methods); all kept off-topic.
Page history
| Date | Change | Reason |
|---|---|---|
| Nov 14, 2026 | Page created from 54 papers. | First version of the page. |
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