Use free tools to calculate optimal bedtimes, wake-up times, power naps, and sleep windows using 90-minute cycles. Wake up refreshed, boost focus, and improve your daily energy.
Sleep Tool helps you align your rest with natural 90-minute sleep cycles. Instead of guessing a bedtime, choose when you want to wake up (or when you can sleep), and we calculate the most refreshing options.
Whether you’re a student juggling classes, a professional with early meetings, or a parent on duty, our tools are fast, free, and work entirely in your browser — no sign-up required.
These tips are general info, not medical advice.
Pick when you want to wake up. We’ll suggest bedtimes that land on full 90-minute cycles.
Going to bed at a specific time? Get ideal wake-up times that match full cycles.
Set a start time and get a smart nap end time (10–25 mins for alertness, or 90 mins for a full cycle).
Choose a time range you can sleep, and we’ll find the best windows that fit full cycles.
All tools run locally in your browser — no data is sent to our servers.
Sleep cycles average ~90 minutes across light, deep, and REM stages. Waking at the end of a cycle tends to feel easier.
Common targets are 4–6 cycles (≈6–9 hours). Life happens — use the planner to get the best you can.
No — they’re general educational tools. If you have ongoing sleep issues, consult a medical professional.
No. The tools calculate entirely in your browser. See Privacy for details on ads/analytics cookies.
Last updated: August 20, 2025
Sleep Tool (“we”, “our”, “us”) respects your privacy. The calculator tools run locally in your browser — we do not collect or store the times you enter.
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Discover more tips on sleep, health, and productivity in our blog.
Learn the science behind sleep cycles and how to wake up with maximum energy.
Read More →Not everyone needs 8 hours! Find your perfect sleep duration with tips backed by science.
Read More →Struggling with late nights? Follow these steps to reset your body clock naturally.
Read More →Questions, suggestions, or collaboration ideas? We’d love to hear from you.
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