🌙 Sleep Cycle Calculator
🔒 Seguro e Cliente-side
Plan your sleep around 90-minute REM cycles. Enter a wake time to see when to fall asleep for 4–6 cycles, or enter a bedtime to see good wake times. The calculator adds 14 minutes for falling asleep so the suggested times match real-world sleep onset.
Adds 14 minutes for sleep latency (the time it typically takes to fall asleep). Your real cycle length may be 80–100 minutes — adjust if you wake up groggy at 90.
How to use
- Pick whether you're starting from a target wake time or a bedtime.
- Enter the time in 24-hour format. The calculator adds a 14-minute fall-asleep buffer and computes 4 to 6 full 90-minute cycles.
- Aim for one of the suggested times. Waking up at the end of a cycle (light sleep) usually feels less groggy than waking mid-cycle.
Adults need 5–6 cycles (7.5–9 hours) on average. 4 cycles (6 hours) is a survival minimum, not a target. Sleep latency varies — if you typically fall asleep in 5 minutes or 30+ minutes, mentally adjust the buffer.