Your tracker doesn't know how rested you are. You do.
Nightbrain inverts the sleep app: your one-tap morning rating is the ground truth, and last night's wearable data has to earn the right to explain it. A small statistical model, trained only on you, refit every night.
Personal beta · iPhone · Oura
Bedtime consistency matters for you.
Does deep sleep predict your mornings?
too uncertain to say · ~19 more mornings
The order of operations is the whole idea.
Before you look at anything.
One tap, 1–5, straight from the notification. Rating before you see any data keeps your answer honest — the score can't anchor how you think you slept.
Trained on you, only you.
Every night your model retrains on your full history: sleep duration and timing, HRV, resting heart rate, temperature. No population averages standing in for you.
When they're earned.
Nothing surfaces until it clears a real confidence bar. Early on, the honest output is "too uncertain to say" — and Nightbrain says it.
A score that contradicts your own body teaches you to distrust yourself.
Sleep researchers have a name for waking up fine and feeling worse after reading your app: orthosomnia. The score isn't lying, exactly — it's just answering a different question than the one you care about. Nightbrain never grades your night. It predicts how you will say you feel, shows its prediction error honestly, and lets the data argue with itself instead of with you.
It teaches you the statistics while it learns you.
Every concept arrives the day it becomes true of your own model. When your first insight unlocks, that's the day you learn what a credible interval is — yours is on screen. When a promising early pattern collapses, that's the overfitting lesson, demonstrated on your own nights. No course, no toy examples. Skepticism included: the statistical bar is real precisely because you'll know enough to call a bluff.
Starts with Oura. Built for whatever you wear.
Nightbrain reads Oura directly today. Apple Health support comes next — which brings Garmin, Coros, Suunto, Polar, and Apple Watch along with it — followed by direct connections for Whoop, Polar, Fitbit, and Withings.