Sleep Calculator

Enter wake-up or bedtime. Uses 90-min REM cycles.

How Sleep Cycles Work

The average sleep cycle lasts about 90 minutes. A full night's sleep consists of 4-6 complete cycles. Waking up at the END of a cycle (rather than in the middle) leaves you feeling refreshed and alert.

How to Use

  1. Enter either your desired wake-up time or bedtime
  2. Click Calculate to see optimal bedtimes or wake-up times
  3. Each suggested time corresponds to a complete 90-minute cycle

Example

If you need to wake up at 7:00 AM, optimal bedtimes are 10:00 PM (6 cycles), 11:30 PM (5 cycles), 1:00 AM (4 cycles).

Pro Tips

  • Consistency is key — go to bed and wake up at the same time daily
  • Aim for at least 7-9 hours for adults
  • Allow 15-20 minutes to fall asleep when planning your bedtime