Sleep Calculator
Sleep works in 90-minute cycles. Wake up between cycles — not in the middle — and you will feel fresh instead of groggy.
Go to sleep at one of these times:
Set your alarm for one of these times:
Times include about 15 minutes to fall asleep. 6 cycles (9 hours) is ideal for most adults; 5 cycles (7.5 hours) is a good minimum. This is an estimate for information only — not medical advice.
How to use
- Pick a mode: plan bedtime from a wake-up time, or plan wake-up from a bedtime.
- Choose one of the big time cards — the green one is recommended.
- Keep a regular schedule for the best results.