Not medical advice. This tool gives general information, not medical advice. Speak to a doctor or a qualified health professional before changing your diet, sleep or exercise — particularly if you are pregnant, taking medication, or managing a health condition. Full disclaimer.
Precision · Instant · Private
Sleep Calculator
Plan bed and wake times around sleep cycles, using the common 90-minute average. Enter when you want to wake up (or go to bed) and see the ideal times to do the other.
SYSTEM ● ONLINE · LOCAL COMPUTE · ZERO UPLOAD
UNIT // SLEEP.CYCLELIVE
Mode
Go to bed at one of these times
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Best option
5–6
Cycles
Quick Answer
How does a sleep calculator work?
// Answer
Sleep runs in cycles that average about 90 minutes. Cycles vary: the first is often shorter and later ones longer, and length differs from person to person and night to night. Waking from deep sleep tends to leave people groggier than waking from lighter sleep, so this calculator times bed and wake around the average cycle. It cannot see your actual cycles, so treat the times as a rough guide. This calculator counts back (or forward) in 90-minute blocks from your chosen time, accounting for roughly 15 minutes to fall asleep, and suggests bed or wake times.
Why use this tool
Wake up less groggy
Waking from deep sleep tends to feel worse than waking from light sleep, and timing sleep around cycles is one way people try to avoid it. The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults sleep 7 or more hours a night on a regular basis; five or six 90-minute cycles come to 7.5 to 9 hours. The highlighted option is six cycles; the list also shows five, four and three. Four and three cycles (6 and 4.5 hours) are less than the 7 hours a night recommended for adults.
FAQ
Frequently asked questions
About 90 minutes on average, but it varies: the first cycle is often 70 to 100 minutes and later ones 90 to 120, and length differs between people and from night to night. Each cycle moves through light sleep, deep sleep and REM sleep.
Adults are advised to sleep 7 or more hours a night on a regular basis (American Academy of Sleep Medicine and Sleep Research Society). Five or six 90-minute cycles is 7.5 to 9 hours, which fits that range.
A healthy adult typically takes 10 to 20 minutes to fall asleep, so the calculator adds 15 minutes. If you usually take longer or shorter, shift the times to match.