About SleepyClock
SleepyClock is a tiny, fast, free sleep calculator. No account, no tracking clutter, no paywall — just a science-based answer to "what time should I go to bed?" or "when should my alarm go off?"
Why we built it
Most people set an alarm and hope for the best. But waking up mid-cycle — during deep sleep — is exactly what leaves you groggy. We built SleepyClock to make the 90-minute sleep-cycle method as easy as typing a time.
How the calculator works
- A full sleep cycle lasts about 90 minutes and ends with lighter sleep, so you wake up feeling alert.
- It adds an average 15 minutes to fall asleep, so the "bedtime" we show is the moment to get into bed.
- Pick 2–6 cycles (3–9 hours) depending on your schedule — 5 cycles is the sweet spot for most adults.
- When you have less than 5 hours before your wake time, it automatically suggests a short nap instead.
Who runs SleepyClock
SleepyClock is run by a single person — an independent developer based in Nanchang, China. There is no company, no team, no investors. Every page, calculation, and line of code is built and reviewed by the same person.
The author is a software engineer by day, a self-taught sleep-science reader by night. SleepyClock started as a personal frustration: existing sleep calculators were either too complicated or buried under ads and popups. The goal here is the opposite — a tool that opens in under a second, gives you one answer, and gets out of your way.
If you ever spot something wrong, please email hello@sleepyclock.top. Corrections are taken seriously and the page is updated within a week.
How this site makes money
SleepyClock is free to use and always will be. The site is supported by ads served through Google AdSense. You will see at most one or two unobtrusive ads per page, clearly labelled.
We do not:
- Sell your data (there is no analytics tied to your identity).
- Accept sponsored content or paid placements that influence our recommendations.
- Run affiliate links disguised as editorial content.
Our editorial decisions — what to write, what to recommend, what to leave out — are made independently of advertisers. See our full Editorial Policy.
How we keep content accurate
Every health claim on this site is backed by a published study or a recognized medical source, listed at the bottom of the relevant page under "References". Where evidence is mixed or weak, we say so.
We update pages when:
- A major new study or guideline is published.
- A reader points out a factual error (about once a month, on average).
- A tool's algorithm is improved.
For the full list of sources behind each calculator, see Sources & Methodology.
Contact us
Questions, corrections, or partnership ideas? Email hello@sleepyclock.top.