Sleep Cycle Alarm Calculator
Sleep happens in roughly 90-minute cycles. Waking up between cycles feels far better than being woken in deep sleep. Pick a mode, enter a time, and get a list of smart options — completely free, no signup needed.
Results count 6 full cycles backward from your wake-up time, minus about 15 minutes to fall asleep. The 7.5 to 9 hour options are marked recommended.
Results count 6 full cycles forward from bedtime, plus about 15 minutes to fall asleep.
Results
How to use
- Choose a mode: I wake up at… (get ideal bedtimes) or I go to bed at… (get ideal wake-up times).
- Enter the time — or press Bedtime = now — then calculate.
- Pick one of the highlighted recommended options (7.5 to 9 hours of sleep).
- Use the copy button to save the list, or switch 12/24-hour format any time.
Why cycles matter
- Each full sleep cycle is about 90 minutes: light sleep, deep sleep, then REM sleep.
- Waking up in the middle of deep sleep causes grogginess — that is why timing by cycles works better than by hours.
- Five to six full cycles (7.5 to 9 hours) is the sweet spot for most adults.
- Keep a consistent bedtime — your body adapts to a regular rhythm faster than to perfect timing alone.
General estimates based on average cycle lengths, not medical advice. If you struggle with sleep regularly, talk to a doctor.