Sleep Calculator: How Much Sleep Do You Need?

This sleep calculator will help you find the best bedtime for you, by maximizing your full sleep cycles. Sleep consists of 90-minutes-long sequences, repeated throughout the night. You'll wake up feeling better if you wake up at the end of a cycle, rather than in the middle of it, so use this calculator to find out what time you should go to sleep if you want to wake up refreshed and alert. And if you are still wondering how important it is to get the right amount of sleep, check how deadly your current sleeping routine is!

The duration of each stage oscillates between 5 and 15 minutes. Early in the night, stages of deep sleep are longer than REM sleep, but this swaps round as the night progresses. People's brains usually don't go from stages 1 to 5, but rather: stages of light sleep, stages of deep sleep, REM, and then back to stages of light sleep and stages of deep sleep.