Sleep Calculator
Waking up at the end of a sleep cycle — not in the middle of deep sleep — is what makes mornings feel easy. Enter the time you need to wake up and this calculator lists the bedtimes that give you 6, 5, 4 or 3 complete sleep cycles, including the ~15 minutes it takes to fall asleep.
TheCalculators — Sleep Calculator
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Recommended Bedtime
21:45
6 full cycles (9 h sleep) before waking at 07:00
Options at a glance
- Wake-up Time
- 07:00
- Cycle Length
- 90 min
- Fall-asleep Allowance
- 15 min
- 6 Cycles
- 21:45 · 9 h
- 5 Cycles
- 23:15 · 7.5 h
- 4 Cycles
- 00:45 · 6 h
Bedtime options
Bedtimes assume ~15 minutes to fall asleep and count backwards in whole cycles so your alarm lands between cycles, when you are lightest asleep. Individual cycles run 70–110 minutes — adjust after a few nights.
Most useful next
Formula
Bedtime = wake time − (cycles × cycle length + fall-asleep time)
Pro tips
- • Count backwards in whole cycles — waking mid-cycle is what causes grogginess (sleep inertia).
- • Adults do best on 5–6 cycles; teenagers often need 6–7.
FAQ
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