Health & Fitness
Sleep Calculator
This sleep calculator suggests bedtime or wake-up times based on 90-minute sleep cycles and a short fall-asleep buffer.
Quick answer
A typical sleep cycle is about 90 minutes.
What this tells you
- •A typical sleep cycle is about 90 minutes.
- •Recommendations target waking between cycles, not mid-cycle.
- •The calculator includes a 15-minute fall-asleep buffer.
How to Use
- 1Choose whether you want bedtime or wake-time recommendations.
- 2Enter your target time.
- 3Calculate to see three suggested options.
How It Works
Formula
Sleep or wake time is offset by N x 90-minute cycles plus a 15-minute fall-asleep buffer.The calculator estimates timings around 4 to 6 full sleep cycles to improve wake-up timing.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
Wake at 7:00 AM
ModeWake
Time7:00 AM
ResultSuggested bedtimes around full-cycle intervals
Common mistakes
- Treating recommendations as medical advice
- Ignoring personal sleep needs outside cycle timing
- Using inconsistent sleep/wake schedule daily
Frequently Asked Questions
No, cycles vary by person, but 90 minutes is a common estimate.
It approximates average time needed to fall asleep.
No. It is a planning aid, not a diagnostic tool.