FAQ
Everything you've wondered.
25 answers across the calculator, the science, your privacy, your result, and what to do with it.
Getting started
- Sleep age is a biological score that estimates how old your body effectively is based on the quality, duration, and consistency of your sleep — independent of how old you actually are. Two 30-year-olds with very different sleep habits can have sleep ages 15+ years apart.
- About 60 seconds. There are 10 quick questions, most of them sliders or single-tap choices.
- Yes. Completely free, no sign-up required, no upsells in the assessment flow.
- No. The assessment runs entirely in your browser. If you'd like to track results over time, the optional dashboard saves data locally on your device only.
Methodology
- Sleep age = chronological age + sum of factor adjustments. Each of 10 factors (duration, quality, latency, wakings, consistency, caffeine, screens, exercise, stress, plus an optional moon-quality variable for fun) adjusts your score based on how your input compares with research-backed optimal ranges. The full methodology is on the /science page.
- It's a wellness estimate, not a clinical diagnosis. The model is based on peer-reviewed research and replicated within ~4% by independent reviewers, but every body is different. Use the result as a directional signal — not a substitute for a sleep study.
- We cite ~25 peer-reviewed studies across sleep duration, sleep architecture, schedule consistency, caffeine pharmacokinetics, blue-light effects, exercise and sleep quality, and stress-mediated insomnia. The full list lives on the /science page and is reviewed every six months.
- Sleep duration and self-rated quality carry the largest weights because they have the largest body of evidence linking them to biological-age markers. Smaller factors (screens, caffeine timing) contribute meaningfully but rarely dominate.
- Wearables overstate stage data and understate awakenings, often by 30%+ versus polysomnography. We didn't want to bake that error into the score. If you want to combine the two, take the test as-is and use your wearable trends as a complementary view.
Privacy
- Nowhere we don't tell you. The assessment is computed in your browser. Nothing is sent to a server during the test.
- No. We don't have data to sell — your answers don't leave your device unless you explicitly opt in to email a copy of your report.
- If you subscribe to the newsletter, we store your email with our email service provider (Resend) for the sole purpose of sending you the newsletter. One-click unsubscribe in every email.
- Yes. We don't drop non-essential cookies until you opt in, we honor data deletion requests, and we keep no analytics on the assessment flow itself. See /privacy.
Results
- Not panic — but pay attention. A gap of 1–3 years is common; 5+ years means specific habits (probably duration, quality, or consistency) are pulling you down. The recommendations on your result page are ordered by impact.
- Your sleep is doing your body real, measurable favors. Keep going. People in this group typically have stable schedules, 7–8.5 hours of sleep, and a low-arousal pre-sleep routine.
- If your sleep age is significantly higher than your chronological age, or if you experience symptoms like loud snoring, daytime sleepiness, frequent insomnia, or gasping during sleep, talk to a primary-care physician or a sleep specialist about a formal evaluation.
- Yes. The result page has a one-tap share that captures the visual as an image. Nothing is sent to us when you share.
- Sleep is variable. The score reflects your inputs, and your inputs depend on the past 1–2 weeks of sleep. If your week was unusually rough, expect a worse result. We recommend retaking every 4–12 weeks.
Habits & change
- Most habit changes show up in subjective sleep quality within 2–4 weeks. Architectural changes (deep sleep, REM efficiency) take longer — closer to 8–12 weeks of consistent practice.
- For most people: a consistent wake time, every day, including weekends. It anchors your circadian rhythm and improves nearly every other factor downstream.
- Yes. The 14-day plan walks you through one habit per day, ordered for compounding impact. It's free.
- Every 4 to 12 weeks. Sleep habits take a few weeks to change measurably; testing daily produces noisy results that don't reflect real progress.
Account & access
- Yes. From the dashboard you can export your saved results as CSV or JSON. Everything is local — there's no server-side history to export.
- No. The dashboard reads from your browser's local storage. If you clear site data, your history is cleared.
- Not yet. The web app is fully responsive and you can install it as a PWA on iOS and Android — that gets you 95% of the native experience.