Bedtime Calculator
Find the best bedtimes based on 90-minute sleep cycles to wake up refreshed at a given time.
How This Works
A full sleep cycle lasts about 90 minutes, moving through light sleep, deep sleep and REM sleep. Waking up at the end of a cycle (rather than in the middle of one) generally feels more refreshing. We also add about 15 minutes for the average time it takes to fall asleep.
Formula
Example
To wake up at 7:00 AM with 5 full cycles (7.5 hours of sleep), you'd want to fall asleep by 11:15 PM — so plan to be in bed around 11:00 PM.
Frequently Asked Questions
What time should I go to bed to wake up at 7:00 AM?
Good options are 2:15 AM (4.5h), 12:45 AM (6h), 11:15 PM (7.5h), 9:45 PM (9h).
Why 90-minute increments?
A full sleep cycle lasts approximately 90 minutes. Waking up at the end of a cycle, rather than mid-cycle, tends to feel less groggy.