Your body keeps its own time.
Circadia keeps up.
A free sleep tracker and forecaster for every rhythm the 24-hour world doesn't fit — Non-24, Delayed Sleep Phase, irregular and fragmented sleep, shift work, and more. Log your sleep. See your true day length. Know when sleep will come — days ahead.
Not a bad habit. A different clock.
Most people's body clocks reset to the sun every morning. In circadian rhythm sleep disorders they don't: with Non-24 (N24) the internal day runs longer — often 24.5 to 26 hours — so sleep laps the entire clock; with Delayed Sleep Phase (DSPD) it locks in hours later than the world expects; with irregular sleep-wake rhythm it scatters. Fighting any of them feels like permanent jet lag. Understanding your own clock changes everything — "unpredictable" sleep becomes something you can plan a life around.
- Monday11:30 pm
- Tuesday12:20 am+50 min
- Wednesday1:10 am+50 min
- Thursday2:00 am+50 min
- Friday2:50 am+50 min
- …and onaround the clock≈ every 29 days
Log it. Understand it. Plan around it.
Everything is computed from your own nights — no generic sleep advice, no 24-hour assumptions baked in anywhere.
Log sleep in seconds
One tap on Sleep now, one when you wake. Or bring years of history from Fitbit, Oura, Garmin, Sleep As Android, a spreadsheet — even pasted sleep notes.
See your true day length
Circadia estimates your body's own period — your τ — from your real nights, plus your drift per day, your trips around the clock, and what actually steadies you.
Know when sleep will come
Forecast your next sleep windows days ahead — with honest uncertainty bands and a report card that grades the forecast against your own past nights.
Answer "will I be awake?"
Type in an appointment and the event check translates it into your body's time — then suggests easier windows when your clock will actually cooperate.
Track a family, not just yourself
Parents log a child's sleep under their own profile, invite a co-parent with one code, and set per-profile thresholds. When they're ready, the whole history graduates with them.
Walk into appointments with proof
A clean, clinician-ready PDF of your rhythm — the staircase chart that explains in one glance what years of "just sleep earlier" advice never understood.
Plans, on a clock that moves.
Two forecast models — a steady one and an adaptive one that learns from your recent nights — both graded openly on your own history, so you always know how much to trust them. No sleep app should ask for faith.
- Tonight2:40 pm± 1.1 h
- Sat3:35 pm± 1.4 h
- Sun4:30 pm± 1.8 h
- Mon5:25 pm± 2.1 h
- Tue6:20 pm± 2.5 h
Live presence, day-length clubs, a poll of the week, and a map of where everyone's clocks are — all anonymous, all opt-in.
Somebody else is awake at 4 a.m. too.
Circadian rhythm disorders are isolating in a very specific way: the world is asleep when you're wide awake, and wide awake when you finally sleep. Circadia's community shows you who shares your hour — your biological hour — and how your rhythm compares with everyone else's. Built alongside a CRSD community from day one; half the features on this page started as someone's Discord message.
Honest by design.
Free
Circadia is free while in open alpha. No ads, no selling your data — ever.
Yours
Export everything any time — backup file, spreadsheet, or PDF. Delete everything just as easily.
Private
Sharing anything — with friends, with research — is strictly opt-in, per item, and reversible. Minors never appear in public features.
Not a diagnosis
Circadia is informational, not a medical device. Bring the charts to a clinician who can do the diagnosing.
Frequently asked.
What is Non-24-Hour Sleep-Wake Disorder (N24)?
A circadian rhythm sleep disorder where the body's internal day runs longer than 24 hours — commonly 24.5 to 26 hours — so sleep arrives a little later each day and gradually rotates around the entire clock. Most common in totally blind people, but it affects sighted people too.
Does Circadia work for DSPD and other rhythm disorders, or only N24?
The full range. Built-in lenses adapt the app for Delayed Sleep Phase (DSPD), Advanced Sleep Phase, free-running rhythms (N24), irregular or fragmented sleep, split and polyphasic sleep, insomnia, daytime sleepiness, shift work and travel, and caregivers tracking a child's or dependent's sleep.
Is it really free?
Yes — free while in open alpha, no ads, and your data is never sold. Ever.
Can I import from Fitbit, Oura, or another tracker?
Yes: Fitbit, Oura Ring, Garmin, Sleep As Android, Eight Sleep, Huckleberry, CSV spreadsheets — even pasted free-text sleep notes. Oura can sync automatically.
How does the forecast work?
Circadia estimates your intrinsic circadian period — your τ — from your own logged nights, then projects upcoming sleep windows days ahead with honest uncertainty bands. Every forecast is graded against your own past nights in a walk-forward report card, so you always know how accurate it's been for you.
Is Circadia a medical device?
No — it's informational, not diagnostic. It produces clinician-ready charts and PDF reports you can bring to a doctor, but diagnosis and treatment belong with medical professionals.
Stop fighting your clock.
Start reading it.
Open Circadia, tap “Try with sample data”, and see what three weeks of a longer day looks like — then start logging your own.