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Sleep Cycle Calculator — Optimal Wake-Up Times
Wake up refreshed by timing your sleep to complete full 90-minute sleep cycles. Avoid waking during deep sleep for more energy and better mood.
Recommended bedtimes to wake at 07:00:
9:46 PM
9.0h · 6 cycles
Excellent11:16 PM
7.5h · 5 cycles
Good12:46 AM
6.0h · 4 cycles
MinimumAnalysis & insights
Sleep cycles run on a ~90-minute rhythm (light → deep → REM, repeat). Waking at the END of a cycle leaves you feeling refreshed; waking mid-cycle (especially during deep sleep) leaves you groggy. The times shown above target completed cycles. Aim for 4-6 full cycles per night (6-9 hours) and pick the wake/bed time that fits your real schedule.
Cycle-aligned sleep schedule
Each option targets the natural end of a 90-minute sleep cycle, minimizing grogginess on waking.
Key insights
Most adults need 4-6 cycles
That's 6-9 hours. Consistent total sleep matters more than the exact number — try a few options for 2 weeks and see which makes you feel best on waking.
Cycle length is approximate
90 minutes is the average. Individual cycles range 70-120 minutes. The first cycle of the night is often shorter; later cycles get longer. If you're consistently waking 10-15 minutes off the suggested times, your personal cycle is just slightly different.
Consistency beats duration
Going to bed and waking at the SAME time daily (even weekends) anchors your circadian rhythm. The body adapts to whatever pattern you reinforce.
Recommended actions(4)
Set a consistent wake time, then back-calculate bedtime
High priorityWake time is the anchor. Bedtime should be 7.5-9 hours earlier (5-6 complete cycles). Don't sleep in on weekends — it shifts your circadian rhythm and makes Monday harder.
Impact: A consistent wake time within ±30 minutes daily is the single most-impactful sleep habit.
Cool, dark, quiet bedroom
High priority65-68°F is ideal for sleep. Blackout curtains or sleep mask. White noise or earplugs if your environment is loud.
No screens 30 minutes before bed
Medium priorityBlue light suppresses melatonin. If you must use a phone, enable night mode or wear blue-blocker glasses.
This tool is for informational purposes only and does not constitute medical advice. Consult a healthcare professional for advice specific to your situation.