Wake up refreshed by aligning with your natural sleep cycles.
About This Tool
Sleep Cycle Calculator plans bedtimes or wake-up times from complete sleep cycles. Waking between cycles can help you feel more alert. All calculations run locally in your browser.
How to Use
Pick a mode: bedtime known or wake-up known.
Enter your time, set cycle length and how many options to show.
Switch 12-hour or 24-hour display. Results update automatically.
Use Copy Times or Clear as needed.
Includes 15 minutes to fall asleep before the first cycle starts.
Sleep Cycle Tips
A full cycle is about 90 minutes (light, deep, and REM sleep).
Most adults do well with 5–6 cycles (roughly 7.5–9 hours in bed).
Adjust cycle length (80–110 min) if you know your rhythm.
Keep a steady schedule and limit screens before bed.