Sleep Calculator
Calculate sleep schedules based on sleep cycles.
Includes ~15 minutes to fall asleep
Suggested bedtimes
11:15 PM
Based on 90-minute sleep cycles
6 cycles (~9.25 h)
9:45 PM
5 cycles (~7.75 h)
11:15 PM
4 cycles (~6.25 h)
12:45 AM
Sleep needs vary. These times aim to wake you near the end of a cycle — not a clinical sleep plan.
In-depth explanation
Plan bedtimes or wake times around 90-minute sleep cycles, including about 15 minutes to fall asleep. Everything runs locally in your browser — your inputs are not uploaded to produce the result.
Sleep typically moves through stages in roughly 90-minute cycles. Waking near the end of a cycle can feel easier. Most people need a short buffer to fall asleep before the first cycle starts.
Five or six cycles (about 7.5–9 hours including fall-asleep time) suits many adults. Use Sleep Calculator for quick planning; confirm important money, tax, or health decisions with an official source or professional when needed.
Ninety-minute cycles are a simplified model of sleep architecture. Real cycles vary, and waking “between cycles” is not guaranteed to feel better. The 15-minute fall-asleep buffer is a guess — insomnia needs different help.
Most adults do well in a 7–9 hour window including that buffer. Shift work and babies break the model. Use the suggested bed or wake times as experiments, not as a diagnosis of a sleep disorder.
Frequently asked questions
What is a sleep cycle?
Sleep typically moves through stages in roughly 90-minute cycles. Waking near the end of a cycle can feel easier.
Why add 15 minutes?
Most people need a short buffer to fall asleep before the first cycle starts.
How many cycles should I aim for?
Five or six cycles (about 7.5–9 hours including fall-asleep time) suits many adults.
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