What Is the Sleep Cycle Calculator?
A sleep cycle calculator computes circadian bedtime and wake-up schedules mapped to ultradian 90-minute sleep cycles.
How Does the Sleep Cycle Calculator Work?
Subtracts or adds discrete multiples of 90-minute sleep intervals along with average sleep onset latency.
Sleep Cycle Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Bedtime = Wake Time - Latency - (Cycles × 90 min); Wake Time = Bedtime + Latency + (Cycles × 90 min)
Maps sleep duration to natural 90-minute ultradian cycles plus average sleep onset latency.
How to Use the Sleep Cycle Calculator
- Specify whether you want to calculate your bedtime from a required alarm time or calculate wake-up options from your bedtime.
Step-by-Step Example Calculation
Waking Up at 7:00 AM with 15-Minute Falling Asleep Buffer
Input Values:
mode:wake_at
targetTime:07:00
latencyMinutes:15
Worked Steps: Optimal recommended bedtime for 5 complete cycles (7.5 hours of sleep) is 11:15 PM.
Understanding Your Result
Provides specific time targets corresponding to 6 cycles (9.0h), 5 cycles (7.5h), 4 cycles (6.0h), and 3 cycles (4.5h).
Factors That Affect the Result
- Caffeine half-life (5–7 hours), evening blue light exposure, bedroom temperature, and individual sleep cycle duration variances (80–120 min).
When Should You Use This Calculator?
- Setting alarms for early flights or morning shifts, beating morning fatigue, and optimizing circadian rhythms.
Assumptions & Limitations
- Assumes a standard 90-minute cycle length. Actual individual cycles can range from 80 to 120 minutes across the night.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Based on American Academy of Sleep Medicine polysomnography sleep architecture models.