How the sleep ranges and bedtimes work
The recommended range comes from the National Sleep Foundation's expert panel: 7–9 hours for adults aged 18–64 and 7–8 hours from 65 1. The panel also named a wider band that may be appropriate for some people, and the tool shows it under your result 1.
The American Academy of Sleep Medicine and the Sleep Research Society recommend at least 7 hours a night on a regular basis for adults 2.
Bedtimes are simple arithmetic: your wake time, minus the hours of sleep, minus your own estimate of how long you take to fall asleep.
How to use your bedtime
Pick one row and keep that wake time on most days. In a study of about 61,000 UK Biobank participants, regular sleep was associated with lower mortality risk, and regularity predicted risk more strongly than duration 3.
Caffeine can quietly cost you sleep: in a small study, 400 mg taken six hours before bed still reduced measured sleep by more than an hour 4. Our guide Sleep deeper covers light, caffeine and when to talk to a doctor.
| Age | Recommended | May be appropriate |
|---|---|---|
| 18–25 | 7–9 h | 6 h, 10–11 h |
| 26–64 | 7–9 h | 6 h, 10 h |
| 65+ | 7–8 h | 5–6 h, 9 h |
Questions people ask
How much sleep do I need at 40?
For adults aged 26–64, the National Sleep Foundation recommends 7–9 hours a night 1. The AASM and Sleep Research Society recommend at least 7 hours on a regular basis 2.
Is 6 hours of sleep enough?
For most adults it falls short of the recommended 7–9 hours, although the National Sleep Foundation panel lists 6 hours as possibly appropriate for some people 1. Regularly sleeping less than 7 hours is associated with poorer health in adults 2.
What time should I go to bed if I wake up at 6?
For 7.5 hours of sleep and 15 minutes to fall asleep, lights out at 22:15. For 8 hours, 21:45. Use the tool to set your own wake time and settling time.
Does sleeping in on weekends help?
A big shift on weekends makes your rhythm less regular. In a large cohort study, more regular sleep was associated with lower mortality risk 3. If you need more sleep, an earlier night usually keeps your rhythm steadier than a long lie-in.
Sources
- Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40–43.
- Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843–844.
- Windred DP, Burns AC, Lane JM, et al. Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study. Sleep. 2024;47(1):zsad253.
- Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195–1200.