Sleep Cycle Calculator
Find the best wake-up times based on 90-minute sleep cycles and when you go to bed.
Fill in your details, then check your personalized result and recommendations.
Formula
Wake time = bedtime + (90 min × cycles) + 15 min to fall asleep
Worked example
Bed now → wake after 5 or 6 cycles for refreshed mornings
What the sleep calculator does
Sleep happens in repeating cycles of roughly 90 minutes, each moving through light sleep, deep sleep, and REM. Waking at the end of a cycle leaves you feeling refreshed, while waking in the middle of deep sleep often leaves you groggy. This calculator suggests ideal wake-up times based on when you plan to go to bed.
How the calculation works
The tool adds about 15 minutes — the average time to fall asleep — to your chosen bedtime, then counts complete 90-minute cycles from there. It shows wake times after four, five, and six cycles so you can pick a target that fits your schedule while still ending on a cycle boundary.
How to interpret your result
Most adults feel best after five or six full cycles, equal to about 7.5 to 9 hours of sleep. If you must wake earlier, finishing four cycles is better than waking mid-cycle at an awkward time. These are guidelines — cycle length varies between individuals and from night to night.
Health recommendations
Keep a consistent sleep and wake schedule, limit screens and caffeine before bed, and keep your bedroom cool and dark. Prioritising regular, sufficient sleep supports recovery, mood, metabolism, and overall health as much as diet and exercise do.
FAQ
+How long is a sleep cycle?
About 90 minutes, cycling through light, deep and REM sleep stages.
+Why wake at the end of a cycle?
Waking between cycles, rather than mid-deep-sleep, helps you feel more refreshed.
+How many cycles do I need?
Most adults need 5–6 complete cycles, roughly 7.5–9 hours of sleep.