Health
Sleep Calculator
Bedtime or wake-up time to optimal sleep cycles. Wake up feeling rested, not groggy.
Go to bed at one of these times to wake up refreshed:
Bedtime
9:45 PM
6 cycles
9h 0m
9 hours - Excellent
Bedtime
11:15 PM
5 cycles
7h 30m
7.5 hours - Recommended
Bedtime
12:45 AM
4 cycles
6h 0m
6 hours - Minimum
Bedtime
2:15 AM
3 cycles
4h 30m
4.5 hours - Short nap
How it works: Sleep happens in ~90-minute cycles. Waking at the end of a cycle (rather than mid-cycle) helps you feel refreshed. We also add 15 minutes for the time it takes to fall asleep.
Frequently asked questions
What is a sleep cycle?
A sleep cycle lasts about 90 minutes and includes light sleep, deep sleep, and REM sleep. A full night's rest typically consists of 4-6 complete cycles. Waking at the end of a cycle feels much better than being woken mid-cycle.
How much sleep do I need?
Most adults need 7-9 hours of sleep per night, which equates to 5-6 complete sleep cycles. The calculator recommends 5 cycles (7.5 hours) as the sweet spot for most people.
Why 15 minutes added?
Most people take about 10-20 minutes to fall asleep. We add 15 minutes to account for this, so if you want to wake at 7:00 AM, you should actually get into bed 15 minutes before the calculated bedtime.
Find your optimal bedtime or wake-up time based on natural 90-minute sleep cycles. Wake up feeling refreshed instead of groggy by timing your sleep to cycle boundaries.
Works in both directions: tell us when you need to wake up, and we'll suggest bedtimes, or tell us when you're going to bed and we'll predict your best wake-up times.