Relationship of sleep duration with all-cause mortality and cardiovascular events: a systematic review and dose-response meta-analysis of prospective cohort studies.

Question:

How much sleep is associated with the lowest risk of all-cause mortality and cardiovascular disease-related events and mortality?

Conclusion:

The lowest-risk duration of sleep is 7 hours per day. Both longer and shorter sleep durations were associated with increased risk of all-cause mortality and cardiovascular disease-related mortality.

Process:

67 of 1436 studies qualified for analysis
All studies were prospective
Study quality ranked on a 9-point scale; average rating was 7

Analysis:

Populations were generally healthy (not already diagnosed with heart disease or stroke)
All studies had 3 categories of sleep duration (best amount, too little, too much)
Measures: all-cause mortality and events and mortality related to: cardiovascular disease, coronary heart disease, stroke

Results:

Risk of mortality and cardiovascular events, based on difference from 7-hours of sleep per day:

Risk from the shortest amounts of sleep
- 13% increased risk for all-cause mortality
- 14% increased risk for cardiovascular disease-related events and mortality
- 22% increased risk for coronary artery disease-related events and mortality
- Stroke (no significant findings)
Risk from the longest amounts of sleep
- 35% increased risk for all-cause mortality
- 36% increased risk for cardiovascular disease-related events and mortality
- 21% increased risk for coronary artery disease-related events and mortality
- 45% increased risk for stroke-related events and mortality

Risk of mortality and cardiovascular events based on each hour difference from 7-hours of sleep per day:

For each hour less than 7
- 6% increased risk for all-cause mortality
- 6% increased risk for cardiovascular disease-related events and mortality
- 7% increased risk for coronary artery disease-related events and mortality
- 5% increased risk for stroke-related events and mortality
For each hour more than 7
- 5% increased risk for all-cause mortality
- 5% increased risk for cardiovascular disease-related events and mortality
- 5% increased risk for coronary artery disease-related events and mortality
- 5% increased risk for stroke-related events and morality

Other Information:

Studies do not measure quality of sleep
The follow-up periods to track patients weren’t specified in the review
Most studies occurred before wearable sleep tracking devices (e.g. Fitbits) were invented, so data was reported by patients