Sleep Cycle Calculator
Find the best time to go to sleep or wake up, so you rise feeling refreshed — not groggy.
Recommended times
A full sleep cycle lasts about 90 minutes. Waking at the end of a cycle helps you feel rested. The highlighted options (6 or 5 cycles ≈ 9h / 7.5h) match the adult recommendation of 7–9 hours.
How the sleep calculator works
Sleep happens in cycles of roughly 90 minutes, moving between light sleep, deep sleep, and REM. If your alarm rings in the middle of a deep-sleep phase, you wake up tired — even after a long night. This calculator counts backwards (or forwards) in 90-minute cycles and adds ~15 minutes for falling asleep, so your wake-up lands at the end of a cycle.
🌙 Plan by wake-up
Enter the time you must get up. We list the bedtimes that let you finish full cycles before the alarm.
⏰ Plan by bedtime
Going to bed now? We tell you the ideal wake-up times to rise energised.
💤 7–9 hours
The highlighted results match the adult sleep range recommended by sleep experts.
Want to sleep better tonight?
Read our quick guides on how much sleep you really need and how to fix your sleep schedule.
Read sleep tips →