Sleep Calculator
Calculate optimal sleep and wake times based on 90-minute sleep cycles for better rest.
What do you want to calculate?
Recommended Bedtimes
Based on 90-minute sleep cycles. Waking at the end of a cycle helps you feel more refreshed.
09:45 PM
optimal
6 sleep cycles
9 hours of sleep
11:15 PM
good
5 sleep cycles
7.5 hours of sleep
12:45 AM
fair
4 sleep cycles
6 hours of sleep
Tip: Try to go to bed at 09:45 PM for optimal rest with 6 full sleep cycles (9 hours).
Understanding Sleep Cycles
Each sleep cycle lasts approximately 90 minutes and consists of four stages:
Light Sleep (N1)
5%Transition between wakefulness and sleep
Light Sleep (N2)
45%Body temperature drops, heart rate slows
Deep Sleep (N3)
25%Physical restoration and immune system boost
REM Sleep
25%Dreams occur, memory consolidation
Recommended Sleep Duration by Age
7-9 hours
Adults (18-64)
7-8 hours
Older Adults (65+)
8-10 hours
Teenagers (14-17)
9-11 hours
Children (6-13)
Tips for Better Sleep
- Maintain a consistent sleep schedule, even on weekends
- Avoid screens for 1 hour before bed (blue light disrupts melatonin)
- Keep your bedroom cool (65-68°F / 18-20°C)
- Avoid caffeine at least 6 hours before bedtime
- Exercise regularly, but not too close to bedtime
- Create a dark, quiet sleeping environment
- Avoid large meals close to bedtime
- Limit alcohol, which can disrupt sleep quality
Disclaimer: This calculator provides general guidelines based on typical 90-minute sleep cycles. Individual sleep needs vary, and sleep cycles can range from 70-120 minutes. If you experience persistent sleep problems, insomnia, or excessive daytime sleepiness, please consult a healthcare professional or sleep specialist.