Sleep Cycle Calculator
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Wake-time suggestions after 4, 5, or 6 sleep cycles from your bedtime — planning aid only, not medical advice.
Rates last reviewed: July 2026
Bedtime
Suggested wake (5 cycles)
6:00 AM
7.5 hours of sleep
- 4 cycles (6 h)
- 4:30 AM
- 5 cycles (7.5 h)
- 6:00 AM
- 6 cycles (9 h)
- 7:30 AM
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Sleep cycles and wake times
Sleep is often described in repeating cycles of lighter and deeper stages, commonly about 90 minutes each. Waking near the end of a cycle — when sleep is lighter — may feel easier than waking mid-cycle, though individual sleep architecture varies.
This calculator adds 4, 5, or 6 full cycles (default 90 minutes each) to your bedtime and shows corresponding wake times. It does not account for how long it takes you to fall asleep, night awakenings, or sleep disorders.
Example: bedtime 10:30 PM with 90-minute cycles suggests wake windows around 4:30 AM (4 cycles), 6:00 AM (5 cycles), and 7:30 AM (6 cycles). Use as a rough schedule hint — not a substitute for clinical sleep guidance.
Official sources
Rates and formulas in this calculator reference the documentation below. Confirm current numbers on the source site before relying on them. Links do not imply endorsement by those organizations of Calcometry or this tool.
Reference to CDC materials or links does not imply endorsement or recommendation by CDC, ATSDR, HHS, or the U.S. Government.
Common questions
Is 90 minutes always correct?
No. Cycle length varies by person and night. Some people use 80–110 minutes in apps. This tool defaults to 90 minutes as a common planning reference.
Should I count time to fall asleep?
Many planners add 15–20 minutes before the first cycle starts. This calculator uses your entered bedtime as cycle zero — adjust bedtime earlier if you need buffer time.
Is this medical advice?
No. Sleep needs differ by age, health, and lifestyle. Consult a healthcare provider for insomnia, sleep apnea, or persistent fatigue.