How Much Sleep Do I Need?
Bedtime by age
Sleep need is set by age band. The cycle count follows from the target, not the other way round.
For children under 6, the total includes naps. Subtract nap time from the night target rather than stacking both.
Sleep needs change across your life. The ranges below reflect consensus recommendations from the CDC and sleep-medicine bodies. Treat them as healthy targets rather than hard rules, and let how you feel and function be the final check.
Recommended sleep by age
| Age group | Age | Sleep per 24h | In cycles |
|---|---|---|---|
| Newborn | 0-3 months | 14-17 hours | Cycles are ~50 min and not yet consolidated |
| Infant | 4-11 months | 12-16 hours | Cycles lengthen toward 60 min |
| Toddler | 1-2 years | 11-14 hours | Naps still carry part of the total |
| Preschool | 3-5 years | 10-13 hours | Cycles approach 70-90 min |
| School age | 6-12 years | 9-12 hours | 6-8 cycles |
| Teen | 13-18 years | 8-10 hours | 5-7 cycles, with a later body clock |
| Adult | 18-64 years | 7-9 hours | 5-6 cycles |
| Older adult | 65+ years | 7-8 hours | 5-6 cycles, often lighter and more broken |
Ranges are consensus recommendations from the CDC, the American Academy of Sleep Medicine and the Sleep Research Society. For everyone under about six years old the total includes naps, so subtract nap time from the night rather than stacking the two.
The range is the point
Sleep need is a two-hour band, not a number, and where you sit inside it is partly genetic and partly situational. Illness, hard training, pregnancy, high cognitive load and recovery from sleep debt all push you toward the upper end. Nothing pushes a healthy adult below seven except a rare genetic short-sleep variant, which is far less common than the number of people who believe they have it.
The practical test is not how you feel in bed, it is what happens without an alarm. If you wake naturally within about 20 minutes of your usual time on a free day, you are getting enough. If you sleep two hours longer, you have been running a debt all week.
Hours vs. sleep cycles
Because sleep runs in roughly 90-minute cycles, 7.5 hours (5 cycles) and 9 hours (6 cycles) tend to feel better than in-between amounts that interrupt a cycle. The sleep calculator turns your wake-up time into cycle-aligned bedtimes automatically.
Signs you are not getting enough
- You rely on an alarm and feel groggy for a long time after waking.
- You feel sleepy during the day or fall asleep within minutes of sitting still.
- You sleep much longer on days off, which is a sign of sleep debt.
Next: find your best time to wake up or read about the 90-minute sleep cycle.