Sleep Cycle Calculator Formula
Understand the math behind the sleep cycle calculator. Each variable explained with a worked example.
Formulas Used
Bedtime (6 cycles / 9 hrs)
bedtime_6 = bed_6_cycles >= 0 ? bed_6_cycles / 60 : (bed_6_cycles + 1440) / 60Bedtime (5 cycles / 7.5 hrs) - Recommended
bedtime_5 = bed_5_cycles >= 0 ? bed_5_cycles / 60 : (bed_5_cycles + 1440) / 60Bedtime (4 cycles / 6 hrs)
bedtime_4 = bed_4_cycles >= 0 ? bed_4_cycles / 60 : (bed_4_cycles + 1440) / 60Ideal Sleep Duration
ideal_sleep_hours = 7.5Variables
| Variable | Description | Default |
|---|---|---|
wake_hour | Wake-up Hour (24h)(hour) | 7 |
wake_minute | Wake-up Minute(min) | 0 |
wake_total_min | Derived value= wake_hour * 60 + wake_minute | calculated |
bed_6_cycles | Derived value= wake_total_min - 540 | calculated |
bed_5_cycles | Derived value= wake_total_min - 450 | calculated |
bed_4_cycles | Derived value= wake_total_min - 360 | calculated |
How It Works
Sleep Cycles
One complete sleep cycle lasts approximately 90 minutes. Most adults need 5-6 complete cycles per night.
Waking between cycles (rather than mid-cycle) helps you feel more refreshed.
Worked Example
Waking up at 7:00 AM.
- 01Wake time = 7:00 = 420 minutes
- 026 cycles: 420 - 540 = -120 min => (-120 + 1440) / 60 = 22.0 (10:00 PM)
- 035 cycles: 420 - 450 = -30 min => (-30 + 1440) / 60 = 23.5 (11:30 PM)
- 044 cycles: 420 - 360 = 60 min => 60 / 60 = 1.0 (1:00 AM)
Frequently Asked Questions
How long is a sleep cycle?
A sleep cycle lasts about 90 minutes and includes stages of light sleep, deep sleep, and REM sleep.
How many hours of sleep do I need?
Most adults need 7-9 hours. The ideal amount is 5 complete cycles (7.5 hours), but 6 cycles (9 hours) is also healthy.
Learn More
Guide
Sleep Calculator Guide: Optimize Your Sleep Cycles for Better Rest
Learn how sleep cycles work, how many hours you really need, and how to use a sleep calculator to wake up feeling refreshed. Science-backed tips for better sleep quality.
Ready to run the numbers?
Open Sleep Cycle Calculator