Privacy
The short version: your sleep stays on your device.
Your entries stay in your browser
All the calculators run entirely in your browser. Times, ages, hours slept and diary entries are never sent to us or anyone else.
What is stored on your device
To save you retyping, the site keeps some things in your browser's local storage: your colour theme and 12- or 24-hour clock choice, the settings of each calculator, the week of hours on the sleep debt page and, if you use it, your on-screen sleep diary (dates, bed and wake times, minutes awake, quality ratings and notes). This is personal health information, so it stays only on this device. Pressing Delete all in the diary, or clearing this site's data in your browser, removes it. The name you type on a printable diary is not saved at all.
Page view counts
We use Cloudflare Web Analytics to count page views and see which pages are useful. It does not use cookies, does not track you across other sites, and never receives what you type into the tools.
Hosting
The site is served by Cloudflare. Like any web host, Cloudflare processes your IP address and browser details to deliver pages and protect the site from abuse; see Cloudflare's privacy policy.
Sound and printing
The nap timer's chime is generated on your device. Printing and CSV downloads are created in your browser and go straight to your printer or downloads folder. The site never asks for your microphone, camera or location.
Links to other sites
Links to other websites, including the research we cite and the tools we recommend, are ordinary links. Those sites have their own privacy policies.