Sleep Cycle Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles.
Fall asleep by one of these times:
Based on ~90-minute sleep cycles, plus a 15-minute estimate to fall asleep. Waking up between cycles (rather than mid-cycle) tends to feel less groggy — actual cycle length varies somewhat from person to person.
Overview
Suggests bedtimes or wake-up times aligned to full sleep cycles rather than an arbitrary number of hours, based on the idea that waking between cycles feels more refreshing.
- Works in either direction: from a wake-up time or a bedtime
- Includes a buffer for time to actually fall asleep
- Shows several options spanning different total sleep amounts
How to use it
- 1Choose whether you're setting a wake-up time or bedtime
- 2Enter that time
- 3Pick from the suggested cycle-aligned times
Frequently asked questions
Why 90-minute cycles?
Sleep progresses through cycles of roughly 90 minutes each, moving through lighter and deeper stages. Waking up near the end of a cycle, rather than in the middle of deep sleep, tends to feel less groggy.
Does everyone have exactly 90-minute cycles?
No — this varies somewhat by person and even night to night. 90 minutes is a commonly used average, so treat the suggested times as a helpful range rather than an exact science.