😴 Sleep Calculator

This sleep calculator helps you find the optimal times to wake up or go to bed based on natural 90-minute sleep cycles. Here's how to get the most out of it:

Mode 1 — "I want to wake up at...": Select this tab if you have a fixed wake-up time, such as for work or school. Enter your desired alarm time and click the calculate button. The tool will show you four recommended bedtimes, each corresponding to a different number of complete sleep cycles (3 to 6 cycles). The optimal bedtime with 6 cycles gives you about 9 hours and 14 minutes of sleep, which is ideal for most adults.

Mode 2 — "I want to go to sleep at...": Use this tab if you're going to bed now or at a specific time. Enter your planned bedtime, and the calculator will display the best times to set your alarm so you wake up at the end of a sleep cycle rather than in the middle of deep sleep.

Understanding the results: Each suggested time is color-coded. Green indicates the optimal 6-cycle sleep (recommended for most adults), yellow shows adequate sleep at 4-5 cycles, and red marks the minimum 3 cycles — which should only be used occasionally. The 14-minute fall-asleep buffer is already factored into every calculation, so you don't need to adjust manually.

Tips for better sleep: Try to maintain a consistent sleep schedule even on weekends, avoid screens 30 minutes before bed, and keep your bedroom cool and dark. If you consistently feel groggy despite getting enough hours, you may benefit from tracking your actual sleep patterns and adjusting your bedtime accordingly.