Tools / Health & family
Sleep calculator
Sleep runs in cycles of about 90 minutes, and waking mid-cycle leaves you groggy. Tell us when you must get up and we'll give the best times to go to bed — or tap “Sleeping now” to know when to set the alarm.
Your file never leaves your device — everything runs in your browser
90 minutes is an average — your cycles may differ a little.
How to use it
- Pick “I must wake at…” or “Sleeping now”.
- Adjust how long you take to fall asleep (15 minutes on average).
- Choose a time — the ones marked ✓ give the recommended hours for your age.
Questions
Why 90 minutes?
One cycle (light, deep and dream sleep) takes about 90 minutes in most adults. Waking at the end of a cycle feels easier than from deep sleep. It's an average and varies.
How many hours do I need?
Adults 7–9, teens 8–10, children (6–13) about 9–11, older adults 7–8. We mark the times inside that range.
I can't sleep at all?
This is for planning only. If insomnia, snoring or daytime tiredness persist, see a doctor.