The Science of Sleep Cycles
Feeling groggy when your alarm goes off is a common experience. This is often because you've been woken up in the middle of a deep sleep stage. Understanding sleep cycles can help you time your sleep to wake up feeling more refreshed and alert.
What is a Sleep Cycle?
When you sleep, your brain cycles through different stages: light sleep, deep sleep, and REM (Rapid Eye Movement) sleep. A complete sleep cycle lasts about 90 minutes on average. Waking up at the end of a cycle, when you are in a lighter stage of sleep, is much easier than being jolted awake from deep sleep.
How the Calculator Works
This calculator works backward or forward from your desired wake-up or bedtime in 90-minute increments. It also accounts for the fact that it takes the average person about 14 minutes to fall asleep.
- Wake Up At: If you select a wake-up time, the calculator will suggest several bedtimes. Each suggested time allows for a certain number of full 90-minute sleep cycles (e.g., 9 hours for 6 cycles, 7.5 hours for 5 cycles).
- Go To Bed At: If you choose a bedtime, the calculator will show you the best times to set your alarm, again based on completing full sleep cycles.
Tip for Better Sleep: For most adults, getting 5-6 full sleep cycles (7.5 to 9 hours) is ideal for optimal health and daytime performance. Consistency is key, so try to stick to a regular sleep schedule, even on weekends.