Sleep calculator
Wake up between 90-minute cycles, not in the middle of one. Pick a mode:
FAQ
How does the sleep calculator work?
Sleep runs in roughly 90-minute cycles. Waking between cycles feels easier than waking mid-cycle, so the calculator counts back 5–6 cycles from your wake time, plus about 15 minutes to fall asleep.
How many sleep cycles do I need?
Most adults do best with 5–6 full cycles (7.5–9 hours). The highlighted times give you complete cycles.
What if I'm going to bed right now?
Use the second mode — it shows the best times to set your alarm counting forward from now.
Winding down? Put on a night station — dark scenes, quiet music, and a clock you can read half-asleep.