Circadian Rhythm Calculator
Find your optimal sleep and wake times based on natural circadian rhythms
Calculate Your Optimal Sleep Times
Local sunset time for your location
Local sunrise time for your location
Average duration of one complete sleep cycle
How long it typically takes you to fall asleep
Optimal Sleep Schedule
🌟 Recommended: Bedtime: 22:45
Minimum recommended sleep for most adults
Bedtime: 21:15
Ideal sleep duration for most adults
Bedtime: 00:15
Minimum recommended sleep for most adults
Circadian Rhythm Optimization Tips
Understanding Circadian Rhythms
What Are Circadian Rhythms?
Circadian rhythms are natural, internal processes that regulate the sleep-wake cycle and repeat roughly every 24 hours. They are influenced by environmental cues, especially light and darkness.
Natural Sleep Timing
- •Humans naturally sleep 2.5-4.5 hours after sunset
- •Natural wake time aligns closely with sunrise
- •Sleep cycles typically last 90 minutes (70-120 range)
- •5-6 complete cycles provide optimal rest for most adults
Health Effects of Disruption
Physical Health
Increased risk of obesity, diabetes, cardiovascular disease, and weakened immune system
Mental Health
Higher rates of depression, anxiety, mood disorders, and cognitive impairment
Performance
Reduced alertness, concentration, memory, and increased accidents
Sleep Cycle Guide
Stage 1-2: Light Sleep
Transition from wake to sleep, easy to wake up
Stage 3: Deep Sleep
Physical restoration, growth hormone release
REM Sleep
Memory consolidation, dreaming, brain maintenance
Complete cycles ensure you get adequate deep sleep and REM sleep
Chronotypes
Morning Larks (25%)
Natural early risers, peak performance in morning
Night Owls (25%)
Prefer late bedtimes, peak performance in evening
Third Birds (50%)
Flexible sleep patterns, adapt to schedule changes
Your chronotype is largely genetic but can be influenced by age and lifestyle
Sleep Quality Factors
The Science of Sleep and Circadian Rhythms
How This Calculator Works
This calculator uses established sleep science principles to determine optimal bedtimes based on your local sunrise/sunset times and individual sleep patterns.
Calculation Method
- 1.Identifies the natural sleep window (2.5-4.5 hours after sunset)
- 2.Calculates bedtimes that complete full sleep cycles before sunrise
- 3.Accounts for individual time to fall asleep
- 4.Prioritizes schedules that align with circadian biology
Research Foundation
Pre-industrial Sleep Study
Research on three traditional societies shows natural sleep timing relative to sunset
Sleep Cycle Research
Studies confirm 90-minute average cycles with 70-120 minute individual variation
Circadian Biology
Molecular clock research shows 24.1-hour internal rhythm synchronized by light
Individual Variation: While these guidelines work for most people, individual chronotypes, age, and health conditions may require personalized approaches.
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Medical Disclaimer
This calculator provides general guidance based on sleep research and circadian biology principles. It is not intended as medical advice. Individual sleep needs vary greatly due to genetics, age, health conditions, medications, and lifestyle factors. If you have persistent sleep problems, sleep disorders, or health conditions affecting sleep, consult with a healthcare provider or sleep specialist. Some people may have delayed sleep phase syndrome, advanced sleep phase syndrome, or other circadian rhythm disorders that require professional medical evaluation and treatment.