I want to wake up at
It's now
Nap starting now
Short naps are best before mid-afternoon, so they don't get in the way of tonight's sleep.
Time to fall asleepMost people take 10 to 20 minutes
When to go to bed and when to wake up, in 90-minute sleep cycles.
I want to wake up at
It's now
Nap starting now
Short naps are best before mid-afternoon, so they don't get in the way of tonight's sleep.
| Age | Hours a day | Cycles |
|---|
General guidance from the US National Sleep Foundation (2015). For children, hours include naps. The NHS says most adults need 7 to 9 hours a night. Everyone is different: how you feel during the day matters more than the exact number.
Through the night you go round a cycle of light, deep and dream (REM) sleep that lasts about 90 minutes. Waking at the end of a cycle, in light sleep, usually feels easier than being pulled out of deep sleep.
So the calculator counts back whole cycles from your alarm and adds the time it takes you to fall asleep. Five cycles is 7½ hours and six is 9 hours, which fits the 7 to 9 hours most adults need.
Cycles aren't exactly 90 minutes for everyone (they run from about 70 to 120), so treat the times as a guide, and set them on your phone's alarm.
This is general guidance, not medical advice. If you regularly struggle to sleep, or feel very tired during the day, talk to a doctor.
When to go to bed and wake up · Free health & fitness app for your browser
Work out when to go to bed and when to wake up, in 90-minute sleep cycles. Pick the time your alarm goes off and see bedtimes for six, five and four cycles (9, 7½ and 6 hours), with five and six marked as recommended for adults; or tap Sleep now for the best times to set your alarm. Plan a 20-minute power nap or a 90-minute full-cycle nap, and change the time it takes you to fall asleep (15 minutes to start). Big, readable times in a 12- or 24-hour clock that follows your phone, recommended hours of sleep for every age, and a plain explanation of how it works. Share your times as a card, then set the one you pick on your phone's alarm. General guidance, not medical advice. Works offline; nothing but your settings is saved.
Free to use. Works on iPhone, Android, Mac and PC; add it to your Home Screen to open it like an app.
Guide: What time should I go to bed? Bedtimes by wake-up time