9 meta-analyses
Physical · Concept
Sleep and Metabolic Health
Short sleep is linked with higher risk of type 2 diabetes, obesity and metabolic syndrome, with a U-shape for diabetes and the lowest risk at seven to eight hours.
5 of 9 sources behind this entry were read from the abstract only; they are marked in the sources list.
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When to seek a professional
- Loud snoring with witnessed gasping/choking or breathing pauses plus daytime sleepiness (possible obstructive sleep apnea), refer to a clinician
- Difficulty falling or staying asleep at least 3 nights/week for 3+ months with daytime impairment (possible chronic insomnia disorder), refer to a clinician
- Excessive daytime sleepiness despite adequate time in bed, or falling asleep involuntarily during activities, refer to a clinician
Informational
For most adultsShift workersOlder adults
What the evidence says
What the sources say
Meta-analyses associate short sleep with higher risk of type 2 diabetes, obesity and metabolic syndrome. For type 2 diabetes the dose-response is U-shaped, with lowest risk at seven to eight hours (Shan 2015); for obesity each hour below seven hours raised risk, with no significant long-sleep effect (Zhou 2019); and for metabolic syndrome short sleep carries a dose gradient (Iftikhar 2015; Hu 2022; Malektojari 2025), while long sleep contributes in some analyses but not others.
Common misconceptions
- “Sleep has nothing to do with weight or blood sugar.” Short sleep tracks with worse metabolic markers.
- “Only diet and exercise matter for metabolism.” Short sleep also tracks with higher risk of type 2 diabetes, obesity and metabolic syndrome.
What we won't claim
- Do not claim to diagnose, treat, or cure insomnia, sleep apnea, or any sleep disorder
- Do not promise guaranteed, instant, or permanent improvements in sleep
- Do not present these general hygiene techniques as clinical therapy (e.g., CBT-I) or a substitute for medical care
9 meta-analyses
- Agreement
- Direction recorded for 0 of 9 sources; not yet recorded for the rest.
- The claim's outcome
- Outcome not yet recorded
- Certainty
- No source states a certainty rating.
- How the sources were read
- Some sources are based on abstracts, not full texts.
What each source measured and concluded (9)
meta-analysis · 2025
Pirahesh et al. (2025) — Association between sleep duration and risk of nonalcoholic fatty liver disease: A systematic review and meta-analysis
- What it measured
- Nonalcoholic fatty liver disease (NAFLD)
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review and meta-analysis (observational studies)
- Studies and participants, as stated
- 31 studies; 836,117 participants
meta-analysis · 2015
Shan et al. (2015) — Sleep Duration and Risk of Type 2 Diabetes: A Meta-analysis of Prospective Studies
- What it measured
- Incidence of type 2 diabetes
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Meta-analysis of prospective observational studies
- Studies and participants, as stated
- 482,502 participants; 18,443 incident cases; 10 articles/11 reports
meta-analysis · 2019
Zhou et al. (2019) — Dose-response association between sleep duration and obesity risk: a systematic review and meta-analysis of prospective cohort studies
- What it measured
- Obesity risk by sleep duration
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review and dose-response meta-analysis of prospective cohort studies
- Studies and participants, as stated
- N=12 studies (16 reports)
meta-analysis · 2022
Yang et al. (2022) — Short sleep duration and the risk of nonalcoholic fatty liver disease/metabolic associated fatty liver disease: a systematic review and meta-analysis
- What it measured
- NAFLD/MAFLD risk by short sleep duration
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review and meta-analysis
- Studies and participants, as stated
- N=15 studies; 261,554 participants
- Heterogeneity, as stated
- I2=71.92%)
meta-analysis · 2025
Malektojari et al. (2025) — Association Between Sleep Duration and Related Risk Factors with Metabolic Syndrome: A Systematic Review and Meta-analysis
- What it measured
- Metabolic syndrome (MetS) risk by sleep duration and related factors
- How it was read
- based on the abstract, not the full text
- What the review says it includes
- Systematic review and meta-analysis of observational studies
- Studies and participants, as stated
- N=26 studies; 279,571 participants
meta-analysis · 2022
Hu et al. (2022) — Association of sleep duration and sleep quality with the risk of metabolic syndrome in adults: a systematic review and meta-analysis.
- What it measured
- Association between sleep duration and risk of MetS.
- How it measured it
- Self-administered questionnaires, PSQI, objective sleep measurements.
- How it was read
- read in full text
- What the review says it includes
- Meta-analysis of 62 studies
- Studies and participants, as stated
- N=874,367 participants across 62 studies
meta-analysis · 2013
Holliday et al. (2013) — Short Sleep Duration Is Associated with Risk of Future Diabetes but Not Cardiovascular Disease: a Prospective Study and Meta-Analysis
- What it measured
- Risk of developing type 2 diabetes and cardiovascular disease.
- How it measured it
- Self-report questionnaire.
- Its conclusion, in its own words
- “In contrast, short sleep duration (<6 h) was prospectively related to future, incident type 2 diabetes; this result was corroborated via meta-analysis of 10 prospective studies including more than 440,000 total participants.”
- How it was read
- read in full text
- What the review says it includes
- Prospective cohort study with meta-analysis of 10 prospective studies
- Studies and participants, as stated
- Prospective study: N=241,949 - Meta-analysis: N=447,124 participants across 10 studies
meta-analysis · 2018
Bakri et al. (2018) — Short night sleeping is associated with higher risk of diabetes in older adults
- What it measured
- Risk of type II diabetes.
- How it measured it
- Questionnaire (self-report).
- How it was read
- read in full text
- What the review says it includes
- Meta-analysis of 7 reports
- Studies and participants, as stated
- N=402,397 participants across 7 studies
meta-analysis · 2015
Iftikhar et al. (2015) — Sleep Duration and Metabolic Syndrome. An Updated Dose-Risk Metaanalysis.
- What it measured
- Metabolic syndrome risk by sleep duration
- How it was read
- screened only, not extracted
- What the review says it includes
- Dose-risk meta-analysis of cross-sectional studies
- Studies and participants, as stated
- 18 studies; 75,657 participants
Key sources (9)
Every source below is shown with its study design and links to the original study. This is the audit trail.
meta-analysisAssociation between sleep duration and risk of nonalcoholic fatty liver disease: A systematic review and meta-analysis
meta-analysisSleep Duration and Risk of Type 2 Diabetes: A Meta-analysis of Prospective Studies
meta-analysisDose-response association between sleep duration and obesity risk: a systematic review and meta-analysis of prospective cohort studies
meta-analysisShort sleep duration and the risk of nonalcoholic fatty liver disease/metabolic associated fatty liver disease: a systematic review and meta-analysis
meta-analysisAssociation Between Sleep Duration and Related Risk Factors with Metabolic Syndrome: A Systematic Review and Meta-analysis
meta-analysisAssociation of sleep duration and sleep quality with the risk of metabolic syndrome in adults: a systematic review and meta-analysis.
meta-analysisShort Sleep Duration Is Associated with Risk of Future Diabetes but Not Cardiovascular Disease: a Prospective Study and Meta-Analysis
meta-analysisShort night sleeping is associated with higher risk of diabetes in older adults
meta-analysisSleep Duration and Metabolic Syndrome. An Updated Dose-Risk Metaanalysis.
“Abstract only” means the review read that paper’s abstract, not its full text; “screened only” means it was included at re-screening and not extracted. Both stay in the trail with their DOI, because how a source was read is part of the audit.
Explore all 891 studies in Sleep →
The full evidence base this focus area draws on, every study with its design and DOI.What it is for
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