This sleep calculator helps you determine optimal bedtimes or wake-up times based on your sleep cycles. Here's how it works:

1. Sleep cycles: Sleep occurs in cycles of approximately 90 minutes each. A complete night's sleep typically consists of 4-6 complete cycles (6-9 hours).
2. Waking between cycles: Waking up at the end of a complete sleep cycle, rather than in the middle, helps you feel more rested and less groggy.
3. Fall asleep time: This calculator factors in the time it typically takes you to fall asleep (average is 10-20 minutes).
4. Calculation method: The calculator works backwards from your wake-up time or forwards from your bedtime, providing options for 4, 5, or 6 complete sleep cycles.