Sleep about 7 hours a night on a regular schedule

Moderate value
Evidence A
Buys life
Free
Takes time daily
Some willpower

In plain words

People who regularly sleep less than 7 hours have about a 10% higher chance of dying over the same period. The more irregular the schedule, the higher the risk. The people with the most regular sleep have a 20% to nearly 50% lower risk than the least regular. In other words, how regular your schedule is tells you more about the risk of death than how long you sleep.

Cost: Free. You have to set aside time to sleep, and for most people that means trading phone time for sleep. The hard part is fixing the times you go to bed and get up.
What you get: Pooling 16 follow-up studies (observational, not assigning groups), with 1,380,000 (138万) people and 113,000 (11.3万) deaths, people who slept short had about 12% higher risk of death (RR 1.12). People who slept long had about 30% higher (RR 1.30). Another pooled analysis grouped by sleep duration: the 7-hour group had the lowest risk. For under 7 hours, each 1 hour less raised risk by about 6% (RR 1.06). For over 7 hours, each 1 hour more raised it by about 13% (RR 1.13). UK Biobank has wrist-watch records for about 61,000 (6.1万) people, observational. People were split into five groups by how regular their sleep was. The four more regular groups had 20%–48% lower risk of death than the most irregular group. How regular the sleep is predicts death better than how long it lasts. Another UK Biobank study used wrist watches to measure the sleep timing of 51,562 people, of whom 3,853 developed cardiovascular disease during the period. Social jet lag is the difference between the midpoint of sleep on workdays and on weekends. People with social jet lag of 2 hours or more had about 30% higher risk of cardiovascular disease (HR 1.30, 95% CI 1.11–1.54). This association was also present among people with normal sleep duration.
Notes: What needs fixing is sleeping too little and an irregular schedule; there is no need to deliberately cut your sleep. The higher risk among long sleepers is mostly cause and effect running backward: depression, chronic illness and sleep apnea make people sleep more. Also, the point about a regular schedule is currently supported by two follow-up studies, both observational, which on their own make it grade B evidence. For how to catch up after a late night, see §2.38 (catch up on sleep the night after staying up late).
Evidence grade: A : Specific numbers from meta-analyses, large cohorts or randomized trials; for law and policy, the statute or official text.
Sources: Cappuccio FP 等 (2010). Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep. https://doi.org/10.1093/sleep/33.5.585
Yin J 等 (2017). Relationship of Sleep Duration With All-Cause Mortality and Cardiovascular Events: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies. JAHA. https://doi.org/10.1161/JAHA.117.005947
Windred DP 等 (2024). Sleep regularity is a stronger predictor of mortality risk than sleep duration: A prospective cohort study. Sleep. https://doi.org/10.1093/sleep/zsad253
Kumar N, Krishnamurthy S (2026). Social jet lag is associated with incident cardiovascular disease independent of sleep duration and cardiac genetic risk. Journal of Internal Medicine. https://doi.org/10.1111/joim.70133

Mentioned in

Translated from the Chinese original. Original book, section 2, tip 13. This section is about health and medicines. It is general information, not a substitute for a doctor’s diagnosis or prescription. Content may be out of date and rules differ by place. When you actually deal with an agency, a doctor or a court, follow what local officials, doctors and lawyers tell you. Disclaimer