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Sleep Cycle Optimal Bedtime Calculator

Wake after N × 90-minute sleep cycles (+ 15 min to fall asleep).

Calculates optimal bedtimes for waking up after complete 90-minute sleep cycles to minimise sleep inertia.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Bedtime = wake_time − N × 90 min − 15 min (fall-asleep)

In depth

Calculates optimal bedtimes for waking up after complete 90-minute sleep cycles to minimise sleep inertia.