Sleep Calculator
Find the best bedtimes or wake-up times based on 90 minute sleep cycles. Includes a 15 minute fall-asleep buffer.
Find your best wake-up times
Suggested wake-up times
3:15 AM
3 cycles, 4h 30m
4:45 AM
4 cycles, 6h
Ideal range
6:15 AM
5 cycles, 7h 30m
Ideal range
7:45 AM
6 cycles, 9h
Ideal range
9:15 AM
7 cycles, 10h 30m
10:45 AM
8 cycles, 12h
Based on a 15-minute fall-asleep buffer and 90-minute sleep cycles. Waking at the end of a cycle helps you feel more refreshed.
Frequently Asked Questions about the Sleep Calculator
What is a 90-minute sleep cycle?
A full sleep cycle lasts about 90 minutes and moves through light sleep, deep sleep, and REM. Most adults complete 4 to 6 cycles per night.
What is REM sleep?
REM (Rapid Eye Movement) is the dream stage of each cycle. It supports memory, learning, and mood. REM periods get longer toward the end of the night.
Why should I wake at the end of a sleep cycle?
Waking during deep sleep leaves you groggy (sleep inertia). Waking at the end of a cycle, when sleep is lightest, helps you feel refreshed even with less total sleep.
Why does the calculator add 15 minutes?
On average, healthy adults need about 15 minutes to fall asleep. The buffer makes the suggested times more accurate to real-world wake-ups.
What is sleep debt?
Sleep debt is the gap between the sleep you need and what you get. Chronic shortfalls hurt focus, mood, and immunity. Aim for 5 to 6 full cycles (7.5 to 9 hours) most nights.
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