Home Sleep cycle calculator

Sleep cycle calculator

Wake at 07:00, allow 15 minutes to fall asleep, and use 90-minute cycles. Six cycles is 21:45, five is 23:15, four is 00:45, and three is 02:15. In bed at 23:00, you wake at 08:15, 06:45, 05:15, or 03:45.

21:45

Cycles Asleep Clock Note

Why this exists

Counting 90-minute sleep cycles back from the alarm makes a wake-up less likely to land in deep sleep. This clock is separate from the 25-minute focus timer and from the workout interval.

Skip the 15 minutes it takes to fall asleep and the whole table shifts by one cycle, which is how people end up awake at dawn.

  1. 01How to use it

    Choose whether you know the wake time or the bedtime, then change the minutes to fall asleep and the cycle length.

    The first row is six cycles. Fits marks five and six. Short marks three and four.

    Sample returns to 07:00, 15 minutes, and 90. Copy takes the table, and Share keeps that time in the link.

  2. 02What you get

    The large time is the six-cycle clock. Waking at 07:00 points to 21:45.

    The ring runs from the moment you are asleep to the moment you wake.

    Recent combinations stay in this browser.

    EnteredWake at 07:00

    21:45 6 cycles, previous day
    23:15 5 cycles, previous day
    00:45 4 cycles
    02:15 3 cycles

  3. 03Worth knowing

    Minutes to fall asleep stay between 0 and 90, and a cycle stays between 70 and 110.

    This is not a medical reading. If your own cycle is not 90, change the minutes.

    The times stay on this device. Nothing is sent to a server.

Questions

QWhat is 21:45?
AWake at 07:00, 15 minutes to fall asleep, six cycles of 90.
QWhat is 23:15?
AThe same plan with five cycles.
QWhat is 00:45?
AFour cycles, so the night is short.
QWhat is 08:15?
AWake time after going to bed at 23:00 for six cycles.

How this page works it out

This page counts sleep cycles back from a wake time. Wake at 07:00, allow 15 minutes to fall asleep, and use 90-minute cycles: six cycles is 21:45, five is 23:15, four is 00:45, and three is 02:15.

In bed at 23:00, six cycles wakes you at 08:15, five at 06:45, four at 05:15, and three at 03:45. Five and six are marked as a fit. Three and four are marked short. Minutes to fall asleep stay between 0 and 90, and a cycle stays between 70 and 110.

This is separate from the 25-minute focus timer and from the workout interval. The times stay in this browser and nothing is sent to a server.

  • # sleep
  • # 90 minutes
  • # 21:45
  • # 07:00