The Study
Association of Objective and Self-Reported Sleep Duration With All-Cause and Cardiovascular Disease Mortality: A Community-Based Study.
This study found that people who slept very little or very much were more likely to die sooner, but it doesn't prove that sleep length caused the deaths — it just shows they went together, like how ice cream sales and shark bites both go up in summer, but one doesn't cause the other.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
Scientists tracked how long people actually slept (using machines) vs. how long they thought they slept, then saw who died over 11 years.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 572 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — sleeping too little (≤5h) is strongly linked to dying sooner.
- 2But saying you sleep 9 hours doesn’t mean you actually do — and that false belief still links to higher death risk, likely because of illness or poor sleep quality.
- 3People who actually slept 5 hours or less were 2.4 times more likely to die early than those who slept 7–8 hours.
- 4People who said they slept less than 4 hours or more than 8 hours also had higher death risk — but their guesses didn’t match the machine data.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Journal of the American Heart Association
Year
2023
Authors
Binbin Zhao, Yuxuan Meng, Xiaoying Jin, Wenyu Xi, Qingyan Ma, Jian Yang, Xiancang Ma, B. Yan
Related Content
Claims (6)
If you sleep 8 to 9 hours every night, you’re less likely to have heart problems later on.
People who sleep 5 hours or less each night are more likely to die sooner from any cause or from heart problems than those who sleep 7 to 8 hours, according to sleep measurements taken in labs.
People who sleep too little (4 hours or less) or too much (more than 8 hours) tend to have a higher risk of dying from any cause or heart disease, while those who sleep 7 to 8 hours have the lowest risk—this might mean that how long you think you slept is more about your health problems or poor sleep quality than how well you actually rested.
People often think they slept more or less than they actually did, so when they fill out sleep surveys, their answers don’t match what machines measure — making those surveys less trustworthy for big health studies.
People who say they sleep too little or too much are more likely to die from heart problems, but only those who actually sleep too little (measured by devices) show a clear link—so sleeping a lot might just mean you’re sick or your sleep is bad, not that you’re sleeping too much.
People who sleep more, as measured by devices, tend to live longer and have fewer heart-related deaths—even those who sleep more than 8 hours don’t seem to be at higher risk.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.