1:15 AM
01:15 (24h)
3 cycles · 4.5h
⚠️ Short — naps only
45
Sleep Cycle Calculator
Wake up between cycles, not in the middle of one. 90 min cycle + fall-asleep buffer.
14 min
5minavg 14 min · raise if slow sleeper30min
If you sleep now, wake up at:
2:45 AM
02:45 (24h)
4 cycles · 6h
✅ Sufficient
70
4:15 AM
04:15 (24h)
5 cycles · 7.5h
✨ Ideal for adults
100
5:45 AM
05:45 (24h)
6 cycles · 9h
✨ Ideal for adults
95
Caffeine cut-off time
12:31 AM
Avoid coffee, tea, energy drinks after this time (5h half-life × 4 = 20h clearance)
Nap Recommendations
20 min
Power nap
N1+N2 light sleep only → wake up refreshed, no inertia
90 min
Full cycle nap
1 complete cycle → memory consolidation, creativity boost
Avoid 30–60 min naps — you enter deep sleep but wake before cycle completion, causing grogginess.
Why 90 minutes?
Your brain cycles through light sleep, deep sleep, and REM in ~90-min intervals. Waking between cycles feels natural; waking mid-cycle causes grogginess.
- • 5 cycles (7.5h) — recommended for adults.
- • 6 cycles (9h) — ideal for recovering from sleep debt.
- • 4 cycles (6h) — minimum for cognitive function.
- • 3 cycles (4.5h) — power sleep; avoid if possible.