What time should you go to bed?
Sleep runs in roughly 90-minute cycles. Waking up between cycles — not in the middle of one — is what actually makes mornings feel easier.
Pick a length and we'll count down for you — your tab title updates too, so you can switch away and still see the time left.
20:00
Wake at 2:45 PM
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Why 90 minutes?
Across a night, sleep moves through the same loop of stages roughly every 90 minutes. Landing an alarm at the seam between two cycles, instead of partway through one, is what the calculator above is doing.
Common questions
- How does the 90-minute sleep cycle work?
- Sleep moves through light, deep, and REM stages in a loop that lasts about 90 minutes. You pass through this loop five to six times a night, and each pass looks a little different — early cycles carry more deep sleep, later cycles carry more REM.
- Why does waking up mid-cycle feel worse?
- If your alarm lands in the middle of a deep-sleep stage, your body has to interrupt something it was partway through, which is what causes grogginess. Waking right at the boundary between two cycles avoids that interruption.
- Is 8 hours the right number for everyone?
- Eight hours is a reasonable average, but because cycles run in 90-minute blocks, whole numbers of cycles land closer to 7.5 or 9 hours, not exactly 8. Treat any number here as a starting point, not a rule.
- Are naps bad for nighttime sleep?
- A short nap earlier in the day rarely affects nighttime sleep for most people. Naps taken late, or ones longer than about 30 minutes without completing a full cycle, are more likely to leave you groggy afterward.
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