Sleep Cycle Calculator — Best Times to Sleep or Wake

Wake between cycles, not mid-deep-sleep: enter your alarm — see six ideal bedtimes, fall-asleep buffer included.

Quick answer: Free sleep calculator: ideal bedtimes for your alarm in 90-minute cycles (3-6 cycles, 15-min fall-asleep buffer).

How to use

  1. Choose wake-up or bedtime mode.
  2. Enter the time.
  3. Read the 3-6 cycle options.

About this tool

Waking mid-deep-sleep feels awful even after 8 hours; waking between cycles feels lighter. This tool works backwards from your alarm in 90-minute cycles (3-6 cycles), including the average 15-minute fall-asleep time — plus a wake-time mode.

FAQ

Is 90 minutes exact?
Population average — individuals range 80-120 min; adjust over a week.
Why 6 cycles?
Some adults need 9h — options listed so you can experiment.
15-minute buffer?
Average fall-asleep time — lie down at that minute.
Sleep-now mode?
Bedtime mode shows the alarms that complete cycles from now.
Naps?
One 90-min cycle, or 20 min before deep sleep starts.
Medical note?
Chronic insomnia needs a doctor — this is arithmetic, not medicine.