Sleep Calculator
Pick when you need to wake up and get bedtimes that line up with full 90-minute sleep cycles, or enter a bedtime to see the best times to set your alarm.
How much sleep do you need?
| Age | Recommended sleep |
|---|---|
| Teens 13–18 | 8–10 hours |
| Adults 18–60 | 7 or more hours |
| Adults 61–64 | 7–9 hours |
| Adults 65+ | 7–8 hours |
Sleep runs in cycles of roughly 90 minutes, moving from light sleep to deep sleep to REM. Waking at the end of a cycle, rather than in the middle of deep sleep, tends to leave you less groggy. Five cycles is 7.5 hours; six is 9.
Frequently asked questions
What time should I go to bed to wake up at 6 AM?
For five full cycles (7.5 hours) plus 15 minutes to fall asleep, aim for about 10:15 PM. For six cycles (9 hours), 8:45 PM.
How long is a sleep cycle?
About 90 minutes on average, though it ranges from roughly 70 to 120 minutes and changes through the night.
Is 6 hours of sleep enough?
For most adults, no. The CDC recommends at least 7 hours a night for adults 18–60.