Sleep Calculator
Compute a wake or bedtime that ends at the completion of a sleep cycle so you feel more rested.
- 6 cycles (9.0 h)9 h
- 5 cycles (7.5 h)7.5 h
- 4 cycles (6.0 h)6 h
How it works
Cycles are ~90 min. Target 5–6 cycles (7.5–9 hours) plus ~15 min to fall asleep.
To wake at 6:30 AM, ideal bedtimes: 9:15 or 10:45 PM.
Frequently asked questions
- Are cycles exactly 90 min?
- Average — real cycles vary from 70 to 120 minutes.
- Do naps count?
- Short (20 min) or full-cycle (90 min) naps avoid post-sleep grogginess.
- Is 6 hours enough?
- For most adults no — 7–9 hours is recommended.
- Does age matter?
- Yes — teens and kids need more.
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