What Is the Sleep Cycle Calculator

The Sleep Cycle Calculator uses the 90-minute cycle model to estimate better wake-up times from a bedtime, or recommended bedtimes from a fixed wake-up target. It also includes sleep stage notes, age-based duration references, and weekly sleep debt estimation for routine planning.

How to Use This Tool

1. Choose a mode: Calculate Wake-up Time or Calculate Bedtime.
2. Enter your time and sleep onset delay in minutes.
3. Results are calculated automatically as you type, showing 4-7 cycle-based options.
4. Prioritize the options tagged as recommended (usually 5-6 cycles).
5. Enter your weekly average sleep hours in the sleep debt section to check deficit or reserve.

Key Features

• Two-way planning for bedtime and wake-up time
• 4-7 cycle candidate times with recommendation tag
• Sleep stage and age-based sleep duration references
• Weekly sleep debt estimate with catch-up guidance
• Fully local browser-side processing

Typical Use Cases

• Stable schedules during study and exam periods
• Sleep window planning for early commute mornings
• Recovery rhythm planning during training blocks
• Daily routine optimization and long-term sleep habits

Recommended Sleep by Age

• Infant (0-3 months): 14-17 h
• Toddler (1-2 years): 11-14 h
• Preschool (3-5 years): 10-13 h
• School Age (6-13 years): 9-11 h
• Teen (14-17 years): 8-10 h
• Adult (18-64 years): 7-9 h
• Older Adult (65+): 7-8 h

Ways to Improve Sleep Quality

• Keep a stable bedtime and wake-up schedule
• Get natural light soon after waking
• Reduce caffeine intake after 2:00 PM
• Limit phone and computer use in the hour before bed
• Optimize bedroom conditions: 18-22 C and lower noise

Usage Notes

• The output is for schedule planning and does not replace medical diagnosis.
• Use a realistic sleep onset delay for more useful results.
• If you have persistent insomnia, frequent awakenings, or daytime fatigue, seek professional advice.