About SleepTimingGuide
A free, simple tool to help you plan your sleep around natural 90-minute cycles.
What This Tool Is and Why It Exists
SleepTimingGuide.com is a free online calculator designed to help you plan your sleep schedule around the natural rhythm of sleep cycles. Most people cycle through stages of sleep in roughly 90-minute intervals. Waking up at the end of a cycle — rather than mid-cycle — often feels more refreshing and less groggy.
This tool exists because sleep timing is surprisingly easy to optimize with a little arithmetic, yet most people never think to do it. By entering when you need to wake up, when you plan to go to bed, or when you want to start a nap, you get clear, instant recommendations that align with natural sleep cycle boundaries.
How It Works
The calculator is straightforward:
- Wake time mode: Enter the time you need to wake up and the calculator works backward to suggest ideal bedtimes based on 4, 5, or 6 complete 90-minute cycles.
- Bedtime mode: Enter when you plan to go to bed and the calculator works forward to suggest ideal wake-up times.
- Nap mode: Enter when your nap starts and the calculator suggests end times for a quick 20-minute reset, a single 90-minute cycle, or a longer 3-hour recovery nap.
- Fall-asleep buffer: Most people take a few minutes to fall asleep after lying down. The adjustable buffer (default 15 minutes) is factored into all bedtime and wake-time suggestions.
All calculations happen instantly in your browser. No data is sent to any server, and nothing you enter is stored or transmitted.
Your Privacy and Data
This tool processes everything locally on your device. There are no accounts, no logins, and no personal data collected from the calculator itself. We may use standard analytics tools (such as Google Analytics) to understand general usage patterns — but these are anonymized and do not include what you enter into the calculator. See our Privacy Policy for full details.
Our Commitment to Accuracy
We built this tool to be transparent and straightforward. The 90-minute sleep cycle figure is a widely referenced estimate used in sleep research and sleep hygiene guidance. Individual sleep cycle lengths vary from person to person, and this tool is intended as a helpful planning aid, not a medical or clinical instrument.
Results are estimates for general informational purposes. They are not medical advice, diagnosis, or treatment recommendations. If you have sleep concerns, please consult a qualified healthcare provider.
Contact
Questions, feedback, or suggestions? We would love to hear from you. Reach us at contact@sleeptimingguide.com or visit our Contact page.