Enter your wake-up time and get the best bedtimes for 6, 5, 4 and 3 sleep cycles (90 minutes each + 15 min to fall asleep).
| Input | Result |
|---|---|
| Wake 07:00, 15 min to sleep | 6 cycles: 21:45 · 5: 23:15 · 4: 00:45 · 3: 02:15 |
| Wake 06:30, 15 min | 6 cycles: 21:15 · 5: 22:45 · 4: 00:15 · 3: 01:45 |
| Wake 08:00, 20 min | 6 cycles: 22:10 · 5: 23:40 · 4: 01:10 · 3: 02:40 |
Sleep runs in ~90-minute cycles of light → deep → REM. Counting 90-minute blocks backwards from your wake time and adding ~15 min to fall asleep lands the alarm between cycles, when waking feels lightest.
Adults do best on 5–6 cycles (7.5–9 h). 4 cycles (6 h) is a short-night fallback, not a habit; 3 cycles is an emergency-only nap strategy.
The 15-minute figure is an average. If you typically take 30, add it — the calculator accepts your own fall-asleep time. Lying awake past your planned bedtime? Get up, dim light, retry when drowsy.