Sleep calculator

Sleep calculator (cycles)

You should go to bed at one of these times:

Sleep runs in ~90-minute cycles; waking up at the end of a cycle (not in the middle) leaves you more rested. 15 minutes are added for falling asleep. For guidance only.

This sleep calculator suggests the best times to go to bed or wake up, based on 90-minute sleep cycles.

How it works

Choose whether you want to wake up at a specific time or go to sleep right now, and the tool lists several options — each a whole number of sleep cycles — with the most balanced one marked as recommended. It’s for guidance only and doesn’t replace advice from a sleep specialist.

FAQ

Why 90-minute cycles?

A full sleep cycle lasts about 90 minutes on average. Waking up at the end of a cycle, rather than in the middle of one, tends to leave you feeling more rested.

Why does it add 15 minutes?

Those 15 minutes account for the average time it takes to fall asleep after going to bed, so the cycles are counted from the moment you actually drift off.

Is this tool medical advice?

No. It's a simple guide based on average cycle length. Actual sleep needs and cycle length vary from person to person.