When to Go to Bed to Wake Up Rested
Find the best time to go to bed or wake up based on 90-minute sleep cycles, with age-based sleep recommendations — right in your browser.
Result
This page opens the sleep calculator in reverse mode: you set the time your alarm goes off, and it counts backwards to the moments you should be falling asleep. Each suggestion is a whole number of 90-minute sleep cycles plus the 15 minutes an average person needs to drift off, so a 07:00 alarm yields bedtimes like 21:45 for six cycles or 23:15 for five.
Why cycles matter: a night of sleep is not uniform — you cycle through light sleep, deep sleep and REM roughly every 90 minutes. An alarm that fires at the end of a cycle catches you in light sleep, and getting up feels easy; the same alarm 30 minutes earlier can drag you out of deep sleep, which is what makes some mornings feel broken regardless of total hours.
Pick the option that gives you the recommended amount for your age — for most adults that is five to six full cycles, i.e. 7.5–9 hours. The calculator highlights the variants that fit your selected age group, and everything is computed locally in your browser.