Sleep Calculator
Calculate optimal bedtime and wake-up times based on 90-minute sleep cycles
Sleep Cycle Calculator
How long it typically takes you to fall asleep
Default: 90 minutes (range: 80-120 minutes)
When you want to wake up
Optimal Bedtimes
To wake up at 07:00, you should go to bed at one of these times:
Sleep Cycle Information
Sleep Stages
Light Sleep
Transition from wake to sleep
5-15 minutes
True Sleep
Brain waves slow down
10-25 minutes
Deep Sleep
Physical restoration
20-40 minutes
REM Sleep
Dreams and memory
10-60 minutes
Better Sleep Tips
Keep consistent sleep/wake times
Cool, dark, quiet bedroom (60-67°F)
No screens 2 hours before bed
Avoid caffeine 6 hours before sleep
Regular exercise (not close to bedtime)
Limit naps to 20-30 minutes
Understanding Sleep Cycles
What are Sleep Cycles?
Sleep cycles are repeated patterns of sleep stages that occur throughout the night. Each cycle lasts approximately 90 minutes and consists of four stages: light sleep (N1, N2), deep sleep (N3), and REM sleep. A typical night includes 5-6 complete cycles.
Why 90-Minute Cycles?
- •Waking up at the end of a cycle feels more refreshing
- •Avoids grogginess from interrupting deep sleep
- •Maximizes sleep efficiency and quality
- •Improves cognitive function and mood
Sleep Duration Guidelines
⚠️ Health Warning: Chronic sleep deprivation increases risk of cardiovascular disease, diabetes, obesity, and premature mortality.
Sleep Deprivation Risks
- • Weakened immune system
- • Weight gain and obesity
- • Increased diabetes risk
- • Heart disease and stroke
- • Depression and anxiety
- • Memory problems
- • Reduced concentration
- • Mood disorders
Related Sleep & Health Calculators
⚠️ Medical Disclaimer: This calculator is for educational purposes only and should not replace professional medical advice. If you have persistent sleep problems, chronic insomnia, or suspect a sleep disorder, please consult with a qualified healthcare professional or sleep specialist.