Sleep Calculator: Best Bedtime & Wake Times
Plan bedtimes and wake-ups around 90-minute sleep cycles to wake refreshed and rested
Sleep Planner
Bedtime Options
To wake up at 6:30 AM
9:15 PM
Best pick — 6 cycles (9h sleep)
9:15 PM
6 cycles · 9h sleep
10:45 PM
5 cycles · 7.5h sleep
12:15 AM
4 cycles · 6h sleep
1:45 AM
3 cycles · 4.5h sleep
Includes ~15 min to fall asleep. Waking at the end of a 90-min cycle avoids grogginess.
About this Tool
Sleep runs in ~90-minute cycles, and waking mid-cycle causes grogginess. This calculator counts backwards from your alarm (or forwards from bedtime) in full cycles — adding 15 minutes to fall asleep — so you wake at the lightest sleep stage.
Common Use Cases
Early Workdays
Pick the bedtime that gives 5-6 full cycles before a 6 AM alarm.
Late Nights
If bedtime is fixed, find the wake time that completes whole cycles.
Shift Workers
Plan daytime sleep blocks that still end at a cycle boundary.
Naps & Recovery
Use the 3-cycle option when only a short night is possible.
Pro Tips
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Aim for 5-6 Cycles
Most adults need 7.5-9 hours — the green-tagged options above.
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Keep It Consistent
Same bed/wake times daily trains your body clock better than catch-up sleep.
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Wind Down First
Dim screens and avoid caffeine 6h before bed so the 15-min buffer holds.
FAQs
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