Loading Legacy
If you go to bed at 22:30, try waking at:
3:14 AM
3 cycles · 4h 30m of sleep
4:44 AM
4 cycles · 6h of sleep
6:14 AM
5 cycles · 7h 30m of sleep
7:44 AM
6 cycles · 9h of sleep
How it works
Note: Sleep cycles vary between individuals. These times are estimates to help you plan — actual sleep quality depends on many factors. Consult a sleep specialist for persistent sleep issues.
Sleep Cycle Calculator uses 90-minute sleep cycle science to calculate optimal wake-up times (from bedtime) or bedtimes (from wake time), accounting for the time it takes to fall asleep, to help you wake refreshed.
Sleep Cycle Calculator is a high-performance utility designed to help users streamline their workflow. Built with modern web technologies, it ensures fast processing times and high-quality outputs directly in your browser.
Each sleep cycle lasts approximately 90 minutes and progresses through NREM Stage 1, 2, 3 (slow-wave sleep) and REM sleep. The average time to fall asleep (sleep latency) is 10–20 minutes. Wake times are calculated as: bedtime + fall-asleep-time + (cycles × 90 minutes). The 5-cycle option (7.5 hours) is highlighted for most adults. Recommended sleep: adults 7–9 hours (CDC), teens 8–10 hours, school-age children 9–12 hours.
A complete sleep cycle lasts approximately 90 minutes and includes light sleep, deep sleep (slow-wave sleep), and REM sleep. Most adults cycle through 4–6 complete cycles per night.
Waking up mid-cycle — especially during deep sleep — causes sleep inertia, the groggy feeling that can last 15–60 minutes. Waking at the end of a 90-minute cycle minimizes this effect.
The CDC recommends 7–9 hours for adults (18–60), 8–10 hours for teens (13–18), and 9–12 hours for school-age children (6–12). Individual needs vary.
To wake at 6 AM with 5 complete cycles (7.5h) plus ~14 min to fall asleep, aim to be in bed by 10:16 PM. For 6 cycles (9h), go to bed at 8:46 PM.