Bed at 22:30
Wake at 07:45 (6 cycles, 9 hours of sleep) or 06:15 (5 cycles, 7.5 hours).
Sleep Cycle Calculator
Find bedtimes or wake-up times that fit whole 90-minute sleep cycles.
Go to bed at
Choose a time and select the button.
Runs in your browser — nothing you enter is sent to a server.
How the Sleep Cycle Calculator works
Sleep runs in cycles of roughly 90 minutes. Waking at the end of a cycle, rather than in deep sleep, tends to feel easier. Choose whether you know your wake-up time or your bedtime; the calculator adds about 15 minutes to fall asleep and lists times for 6, 5, 4 and 3 full cycles.
Formulas
Wake-up time
bedtime + 15 min + cycles × 90 min
Bedtime
wake-up time − 15 min − cycles × 90 min
Examples
Up at 07:00
Go to bed at 21:45 (6 cycles) or 23:15 (5 cycles).
Frequently asked questions
Are sleep cycles always 90 minutes?
No — they vary between about 70 and 120 minutes and change through the night. 90 minutes is an average, so treat the times as a guide.
How much sleep do adults need?
Most adults need 7–9 hours a night. Five or six cycles fits that range.
What if I take longer to fall asleep?
Shift the times by the difference. Regular sleep and wake times help most.
Information:
Good to know
For general information only — not medical advice, diagnosis or treatment. Talk to a doctor or other qualified professional about your health.
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