When do you need to be up?
Or tap Now to use the current time.
Results
How it works
Sleep happens in 90-minute cycles — each one moves through light sleep, deep sleep (slow-wave), and REM sleep. Waking mid-cycle leaves you groggy; completing a cycle leaves you alert.
The calculator adds 15 minutes to fall asleep (sleep-onset latency), then counts backward or forward in 90-minute increments. Hitting a natural cycle boundary is the goal.
Most adults need 5–6 full cycles (7.5–9 h). The gold option is the sweet spot for the majority. Use the 4-cycle option only when you have no other choice.
Quick tips
- → Keep your wake time the same every day — even weekends. This anchors your circadian rhythm.
- → Dim lights and avoid screens 30–60 min before the calculated bedtime.
- → A cool room (65–68 °F / 18–20 °C) helps you fall asleep faster, shrinking that 15-min estimate.
- → If you nap, keep it under 30 min to avoid entering a full cycle.