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What time should I wake up if I go to sleep at 10:00 PM?

If you go to sleep at 10:00 PM, wake up at 7:15 AM (6 cycles), 5:45 AM (5 cycles) or 4:15 AM (4 cycles). These times include about 15 minutes to fall asleep.

I'm going to bed at

Set your alarm for

  1. 7:15 AM6 cycles · 9 h of sleep
  2. 5:45 AM5 cycles · 7.5 h of sleep
  3. 4:15 AM4 cycles · 6 h of sleep

What to do with the number

  1. Set your alarm for the time shown, then aim to be in bed with the lights off about 15 minutes before the bedtime.
  2. Pick 5 or 6 cycles on work nights. Four cycles (6 hours) is a short night; do it rarely.
  3. Keep the same wake time every day, weekends included. A steady wake time does more for mornings than any single perfect bedtime.

Common questions

Why 90 minutes?

A full cycle of light, deep and REM sleep lasts about 90 minutes on average. Waking at the end of one usually feels less groggy than waking out of deep sleep.

Why add 15 minutes?

Most adults take 10 to 20 minutes to fall asleep. Without it, every time would be slightly off.

How much sleep do adults need?

At least 7 hours a night for adults 18 to 60, according to the CDC. That is 5 cycles with time to fall asleep.

One thing this cannot do

Cycles vary from roughly 70 to 120 minutes between people and through the night. This calculator uses the average, so treat the times as a starting point: if you keep waking just before the alarm, your cycles are probably a little shorter.

Sources: NIH StatPearls, Physiology, Sleep Stages · CDC, About Sleep.General information, not medical advice.

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