cv.cm
All lessons

Text

How to find the best bedtime

You have an alarm time. You will find the bedtimes that end a whole sleep cycle, so the alarm rings in light sleep instead of deep sleep. A cycle is about 90 minutes and falling asleep takes about 14 minutes. For a 07:00 alarm, five cycles means lights out at 23:16.

6-minute read

Today's result A short list of bedtimes for six, five, four and three cycles, or wake-up times if you start from your bedtime.

Open the sleep calculator when you know your alarm time. Pick five or six cycles on a normal night. The shorter options are for nights when you must. Nothing is uploaded.

Open Sleep calculator
Contents

  1. Know the two numbers

    One cycle is about 90 minutes: light sleep, deep sleep, then REM. Falling asleep takes about 14 minutes. Waking at the end of a cycle feels lighter than waking in the middle of one.

    Six to three cycles of 90 minutes count back from a 07:00 alarm, each plus 14 minutes to fall asleep.
    Six to three cycles of 90 minutes count back from a 07:00 alarm, each plus 14 minutes to fall asleep.

  2. Open Sleep calculator on cv.cm

    Wake-up time is selected and 07:00 is filled. The bedtimes sit on the right. Nothing leaves this tab.

    Open Sleep calculator

  3. Enter your alarm time

    Type the time the alarm rings, for example 06:30. Four bedtimes appear: six cycles (9 hours), five (7.5), four (6) and three (4.5). The two longest are marked.

  4. Pick five or six cycles

    For 07:00, six cycles is 21:46 and five is 23:16. Most adults do well on 7.5 to 9 hours. 00:46 (four cycles) and 02:16 (three) are for short nights, not every night.

  5. Or start from your bedtime

    Switch I know my to Bedtime and enter when you lie down, for example 23:00. The list flips to wake-up times: 03:44, 05:14, 06:44 and 08:14. Set the alarm on one of them.

    A 23:00 bedtime plus 14 minutes gives wake-up times at 03:44, 05:14, 06:44 and 08:14.
    A 23:00 bedtime plus 14 minutes gives wake-up times at 03:44, 05:14, 06:44 and 08:14.

  6. Adjust to yourself

    If you usually fall asleep in five minutes, go to bed nine minutes later than the list says. If you wake groggy at the suggested time, try the next cycle up or down for a week. Copy puts the list on the clipboard.

Use with these tools

FAQ

Can I find a bedtime free online?

Yes. cv.cm counts the cycles in this tab. Nothing is uploaded or stored.

Why 23:16 for a 07:00 alarm?

Five cycles of 90 minutes is 450 minutes, plus 14 minutes to fall asleep, counted back from 07:00.

How many hours should I sleep?

Five or six cycles, 7.5 to 9 hours, suit most adults. Three or four cycles are shown for nights when you have no choice.

Is every cycle exactly 90 minutes?

No. Cycles range from about 70 to 120 minutes and change through the night. Treat the times as a starting point and adjust by how you feel.

Does it set an alarm?

No. It only lists times. Set the alarm on your phone or clock.