CIRCADIA Open the App

A free sleep tracker for Non-24, Delayed Sleep Phase, and other circadian rhythm disorders Some days are 25 hours long.

Circadia is for people whose body runs on a longer day, a later one, or no steady one at all. Log when you sleep and when you wake. Circadia works out how long your day really is, and tells you when the next sleep is coming.

Open Circadia See What It Does

Free. No download, no card. Works in your browser and installs to your phone.

Two clocks.

Every clock you own tells the world's time. The gold one in Circadia tells yours.

It comes from your own logged sleep, so you can look at 9 am and know whether it's your morning or your 3 am.

Body midnight, day 3: 3:00 am on the wall clock. wall clock a 25-hour body

Sleep that walks around the clock.

Most body clocks run a little long, and morning light nudges them back every day. In Non-24 that nudge doesn't work. The body's day runs 24.5 hours, or 25, or longer, so sleep starts a bit later every day until it has gone all the way around the clock.

Doctors look for it in a sleep diary: one row per day, at least two weeks of them, with the hours you slept shaded in. Move the slider to change the length of the day.

Circadia keeps this diary for you as you log, and works out τ (tau), the real length of your day, from it. How Non-24 works, with sources.

25.0 h

A 25-hour day.

asleep where a 24-hour sleeper stays

You log two times a day. Circadia does the rest.

  1. Your log

    Sleep Now when you lie down. Wake Now when you get up. Add tags and notes if you want them, or bring years of history from Apple Health, Fitbit, Oura and others.

    that +51m is your drift
    Circadia's Log tab, from the App Store set: 86 sleeps, 7h 28m average sleep, plus 36 minutes average drift, the Sleep Now button, and night cards each marked with how much later it started, like plus 51 minutes.

  2. Your rhythm

    How much later each sleep starts, and τ, the real length of your day. Drawn the way sleep labs draw it, for as many years as you've logged.

    Circadia's Rhythm view, filled with the sample log: drifting 33 minutes later each day, a 24.6-hour body day that laps the clock about every 44 days, and a month of sleep climbing later across the chart.

  3. The forecast

    Your next sleep windows, days ahead. Every model is graded afterward against what really happened, so you know how far to trust it.

    even the models get report cards
    Circadia's Next 14 Days: next sleep at 12:21 am, Event Check, and the predicted windows for the coming nights, each with its chance of starting in the window.

  4. A day built from your wake

    Woke at 3 pm? Your meds and meals move with you. The plan starts from when you woke up, not from the clock on the wall.

    Circadia's Clock: a dial of the last 14 days of sleep in rings around the last wake at 7:11 am, and today's plan below it, with meds, meals, wind-down and bed placed from that wake.

  5. Some of it is just for fun

    Daily puzzles that reset at your own midnight, not the world's. Sign in and you're on the leaderboards too.

    Circadia's Games: Inference, Synapse and Tessera, each with a new puzzle at your midnight.
Plus

Will I be awake for it?

Name an appointment once. Event Check tells you whether you're likely to be awake or asleep then, what time it will feel like to your body, and which times that week would be easier. You can also hand it a calendar file you exported, and it pulls the appointments out for you. The file itself is never uploaded.

DentistTuesday, 9:00 am
To your body it feels like3:10 am
Likelyasleep
Easier this weekThursday, 4:00 pm
an example
Free

Show your doctor what your sleep does.

The Doctor's Report is a PDF with your summary numbers, an actogram over the range you pick, your recent sleeps, and how each number was made. It ends with plain-language pages on Non-24 and the other circadian rhythm disorders, for a doctor who may never have seen one.

Or make a QR code. The clinic scans it and opens a read-only page of your last 90 days, with no app and no account. You can revoke it whenever you want.

Free

Track a family, not just yourself.

Add a profile for your child and log their sleep from your account. Send a co-parent an invite code and you both log to the same profile, instead of keeping two copies. Each profile keeps its own sleep goal and thresholds.

When they're 13 or older and ready for their own account, they can graduate. One code moves their whole sleep history over to them.

Plus

So people can see when you'll be asleep.

Subscribe once from Apple Calendar, Google Calendar or Outlook, and your predicted sleep shows up next to everything else. When the forecast changes, the calendar changes too, so the people booking your time can see when you'll be asleep.

Bring your history.

Years of sleep come in at once, so your rhythm fills in from the first day.

Apple HealthFitbitOura RingGarmin, through GuavaAutoSleep Sleep As AndroidSleepmeterEight SleepHuckleberry A spreadsheetPasted notesA Circadia backup

Oura can also sync on its own. Connect it once in Settings and new nights arrive by themselves.Plus

Everything else it does

Log

  • Two times, and anything else you wantQuality, mood, and tags for light, caffeine, melatonin, stress, illness, medication, and screens.
  • Nights that were not nightsA one-tap "did not really sleep", and split sleeps grouped as one.
  • Bring your historyApple Health, Fitbit, Oura, Garmin (through a Guava export), AutoSleep, Sleep As Android, Sleepmeter, Eight Sleep, Huckleberry, a spreadsheet, pasted notes, or a Circadia backup.

Understand

  • Your day length, τMore than one estimator, with a confidence tier, so a number never looks surer than it is.
  • Drift and the actogramHow much later each sleep starts, drawn the way sleep labs draw it.
  • What moves youEach tag against your own other nights. Caffeine nights against the rest. Light nights against the rest.Plus
  • Body timeWhat your 9 am meeting feels like to you, and a Time Zone Passport naming the city whose clock matches yours.

Plan

  • The forecastYour next sleep windows with an uncertainty range. Every forecast model, from a steady one to an adaptive one that learns from your recent nights. The next night is free.all 14 nights are Plus
  • The report cardEvery forecast graded afterward against the sleep that happened.
  • Event Check, calendar, remindersType in an appointment and get an answer in your body's time. The forecast can go on your Apple or Google Calendar and moves when you do.Plus

Share, or don't

  • Doctor's ReportA PDF with the summary numbers, an actogram over the range you pick, your recent sleeps, and how each number was made. Or a link a clinic can open.
  • CircleLet specific people see a slice of your sleep, at a level you choose.
  • LensesFree-running (Non-24), delayed and early sleep, planned multi-sleep, fragmented and irregular sleep, insomnia, hypersomnia and sleep inertia, sudden sleep and cataplexy, baby and child sleep, school-age sleep, caregiver recovery, following someone else's clock, shift work and travel, and the Pattern Finder.
  • YoursExport everything as a backup, a spreadsheet, or a PDF. Delete everything. Neither asks why.

Other people on your hour.

Most people with Non-24 have never met anyone else who has it.

People pick a character instead of a photo. There are daily games, community polls, and a Discord where a lot of the app gets decided.

Join the Discord

Your log can help the research.

Every log in Circadia is private unless you say otherwise.

If you want to, you can share yours with the research cohort. Your name, email and account are stripped first. You pick how much, and you can stop sharing whenever you like. The one thing that can't be pulled back is a dataset that has already been published.

The shared logs are how we learn what Non-24 looks like across a lot of people: how long people's days really run, what moves them, and how to forecast them better.

If you share, you pick the level. These are the four choices in the app:

  1. Share with CircadiaOnly the developer sees it, to make the predictions better.
  2. Share with researchersAcademic collaborators, under a written data-use agreement, to study Non-24.
  3. Include in published researchIt can appear in a published dataset or paper. A published snapshot stays published, but you can stop any future use.
  4. Also share my tag namesYour custom tags go as anonymous codes unless you turn this on.
How the Math Works Read the Journal

Why I made it.

I have Non-24. My sleep starts hours later every day, and some weeks I'm awake for two days at a stretch.

I wanted an app that would let me type in my own sleep and tell me when the next one was coming. None of the ones I tried could do either. So I built one.

I teach contortion. Students kept booking me for 4 pm, while I was asleep. That's why your forecast can go in your calendar.

Most of what's in Circadia now came from the people using it. They find the bugs, they vote on what's next, and some of them share their logs so the math gets better for everyone.

If something's wrong or missing, tell me.

Dayah Founder of Circadia

Free, and Plus.

Everything you need to track it and show a doctor is free. Plus pays for the parts that cost real computing to run.

Free

No ads. No card. No trial clock.

  • Logging, tags, notes, and every import
  • Drift, τ, and the actogram
  • The next night from every forecast model, and the report card
  • Body time and the Time Zone Passport
  • The Doctor's Report PDF
  • Community, a child's profile, themes, export, delete

Plus

A subscription, or one lifetime payment.

  • Adaptive's full forecast, trained on your own nights
  • The full 14-day forecast from every model
  • Event Check, calendar sync, and wake and plan reminders
  • Oura sync
  • What your tags do to your sleep, and the other deep-dive analysis
  • Unlimited members in your Circle
  • Premium themes and the full Tessera picture set

Your log is yours. Sharing of any kind is opt-in, per item, and reversible. Minors never appear in public features. Your data is not sold. Circadia is informational, not a medical device.

Questions.

What is Non-24-Hour Sleep-Wake Disorder?

A circadian rhythm sleep disorder in which the body's internal day runs longer than 24 hours, commonly 24.5 to 26 hours, and does not reset to daylight each morning. Sleep starts later each day and slowly rotates around the clock. It is most common in totally blind people. Sighted people have it too, and are often diagnosed with something else first.

Does it work for Delayed Sleep Phase and the others, or only Non-24?

The full range. There is a lens for each pattern, from Delayed Sleep Phase to shift work to a child's sleep with a co-parent.

Is Circadia free?

Yes. Logging, every import, drift, τ, the actogram, the next night from every forecast model, the report card, and the Doctor's Report are free, with no ads. Plus covers the parts that cost real compute to run: all 14 nights of every forecast, Event Check, calendar sync, reminders, Oura sync, and the deep-dive analysis.

Is my sleep data private?

Yes. Your log is yours. Sharing with a friend, a doctor, the community, or research is opt-in, per item, and reversible. Your data is never sold, and you can export or delete everything at any time.

Can I import from Fitbit, Oura, or Apple Health?

Yes. Apple Health, Fitbit, Oura, Garmin (through a Guava export), AutoSleep, Sleep As Android, Sleepmeter, Eight Sleep, Huckleberry, a spreadsheet, or pasted notes. Oura can also sync on its own with Plus.

How does Circadia predict when I will sleep?

It estimates your τ from your own logged sleeps, then projects the next windows with an uncertainty range. Every forecast is graded afterward against the sleep that actually happened, so you can see how accurate it has been for you before you trust it.

Do I need a diagnosis to use it?

No. Many people start logging before a diagnosis, and a few weeks of logged sleep is often what makes the pattern visible to a doctor.

Is it a medical device?

No. It is informational, not diagnostic. It makes charts and a report you can bring to a doctor. Diagnosis and treatment belong with medical professionals.

Sunny asleep in the crescent moon.

Stop fighting your clock. Start reading it.

Tap “Try with Sample Data” and every chart fills in before you log a single night. Then log the sleep you just had.

Circadia's Calendar on an iPad, filled with the sample log: October with a bar for each day you were awake, and this month's sleeps listed below.
Open Circadia