Sleep Cycle Calculator

This sleep cycle calculator helps you pick a bedtime or wake-up time based on sleep cycles. A commonly cited figure is that a cycle lasts about 90 minutes, so waking at the end of a cycle may feel easier than waking in the middle of one. Enter when you want to wake up and see suggested times to go to bed, or enter a bedtime and see possible wake-up times. It can also help you plan a nap. Cycle length varies between people and with age, so the results are an educational estimate, not medical advice. If you have ongoing trouble sleeping, feel tired despite enough hours, or have concerns about your child's sleep, consult a clinician. The tool is free, needs no account, and runs in your browser, so your sleep times are not uploaded. It also works offline once the page has loaded, which is handy when you plan your night.