I have N24 and got tired of apps that don’t understand how we sleep, so I built one. 

Nothing on the market actually handles drift. They assume one consolidated sleep per day, they don’t know what to do with sleepless nights, and they definitely don’t know what to do with us. So I built something that does.

It’s called Circadia and the alpha is live at circadia.owlandkestrel.com. Core features are free and will stay that way, including tracking, drift math, exports, and the doctor’s report.

What it does:

🛏️ Logging — Sleep onset/wake/duration/quality, wake type (natural vs forced, because the math accounts for alarm-forced onsets), stress/illness/medication flags, post-wake mood + cognition check-ins, sleepless-night logging, and auto-detected crash naps with manual override.

📊 The math — Daily drift, variability (steady drift vs chaotic), estimated tau, live sleep pressure updated by the minute, and 14-day sleep debt in plain English (“you’re 38 hours short this fortnight, that’s severe”). Tunable for polyphasic, ME-CFS, and split sleep.

🔮 Predict — Upcoming sleep window forecasts plus an event predictor: type any date/time and see what biological time it lands at, with a confidence score based on your personal sigma.

📅 Chart + Calendar — Interactive drift chart, symptom overlays, mood/cognition trends, and a calendar view with predictions.

📄 Doctor’s report PDF — Multi-page clinical summary with your chart, stats, and recent log. Pick your disorder (N24, DSPS, ASPS, ISWRD, shift work, or general CRSWDs) and it renders the correct ICD-10 code, diagnostic criteria, treatment options, and an honest entrainment-limits caveat with real response rates and references. Built specifically so you can hand it to a sleep doctor who has never heard of N24 and have them actually have something to work with.

📤 Import/export — Import from Sleep As Android, Fitbit, or a Circadia backup. Export as JSON, text log, PDF, or SVG chart anytime.

Coming soon:  
	•	📱 Native iOS + Android (TestFlight beta in \~1-2 weeks, comment if you want in)  
	•	⏰ Smart alarms + push notifications  
	•	🩺 HealthKit / Google Fit / Fitbit / Oura import  
	•	🤝 Partner/caregiver sharing  
	•	☀️ Light exposure + medication logging for entrainment attempts  
	•	📅 Calendar integration so your biological night shows up as an actual blocked event (with zoom integration as well)  
	•	🧠 Mood/cognition correlation with sleep quality + drift  
	•	💊 Phase-response-curve modeler to predict whether melatonin at time X helps or hurts  
	•	🌀 Polyphasic-aware predictions (known limitation right now; you can manually exclude entries to keep your data clean in the meantime)

A couple of asks:  
\- I’m capping the alpha at 100 users so I can actually keep up with feedback.  
\- If you do sign up, \*please\* consider toggling on “share my data with the developer” in your account menu. Anonymized, opt-in, revocable anytime. There’s almost no public data on N24 patterns anywhere, and drift prediction gets meaningfully better with real data behind it.

And please tell me if you find bugs. This is my first app and I’m still learning. 💜 I’m actively working on it in the alpha stage, so expect it to change occasionally (your data will stay safe!). 

N24 App (Alpha launch, native iOS & Android coming soon)