Your watch said 92. Your BRI was 24. Both are right.

One of the more confusing morning experiences for someone using both a watch and a phone-based sleep monitor goes like this: the watch reports a strong night ("Sleep score: 92, you slept like a champion") and the phone reports something concerning ("BRI 24, in the moderate-OSA range").

The instinct is to ask "which one is wrong?" Reasonable instinct, wrong question. Both are right. They're measuring different things.

I want to walk through what each of them is actually telling you, because once you see it, the contradiction stops being a contradiction.

What a watch sleep score actually measures

"Sleep score" is a composite. The exact recipe varies by manufacturer, but the ingredients are similar: how long you were in bed, how much of that time you were estimated to be in deep or REM sleep, how much you moved around, how stable your heart rate was, and (on devices with the sensor) how stable your blood oxygen was. The score blends those into a single number on a 0–100 scale.

It's a useful summary. It correlates reasonably well with how rested you'll feel. The components it draws from are real signals.

What the score is not is a measurement of breathing events. The watch typically can't tell whether your airway closed for 11 seconds at 3:47 a.m. and ended with a gasp — unless that event was big enough to disturb your heart rate or oxygen long enough for the watch to flag it as a "possible breathing disturbance." Many events don't reach that threshold.

So a high sleep score means: you slept long enough, you reached the expected stages, your heart rate stayed stable, and your overall night looked unremarkable from the wrist. All of which can be true on a night where, acoustically, breathing pauses are stacking up.

What BRI measures

BRI — Breathing Irregularity Index — is the per-hour count of breathing-irregularity events SomniSense detects acoustically. Apneas (full pauses ≥ 10 seconds), hypopneas (significant reductions ≥ 10 seconds), divided by hours of sleep. It uses the same scale clinicians call AHI in lab studies. (See Understanding BRI for what the number is and isn't.)

What BRI does not measure: how long you slept, what stages you reached, how rested your nervous system feels, whether your heart rate was stable. Those are real signals; they're just not in this number.

So a BRI of 24 means: regardless of whether the rest of the night looked good on a watch, your breathing was disturbed at a rate that, in a lab, would be in the moderate-OSA range. That number doesn't depend on whether you also got enough deep sleep, or whether your HRV was solid.

Why both can be high — and what it means when they are

Some bodies are very good at maintaining sleep architecture even under acoustic disruption. The breathing pauses happen, the body briefly arouses, the airway re-opens, and the sleep stages keep cycling more or less on schedule. The watch sees a normal night because the wrist signals stayed within range. The phone catches the breathing events because microphones don't depend on heart rate to register them.

This is a real pattern, and it's actually one of the more clinically interesting ones. A high sleep score with a high BRI suggests:

• You're tolerating breathing disruption better than the average person — for now. Younger and more cardiovascularly fit bodies often do.
• The disruption is still happening, and the long-term cardiovascular and cognitive load is real even if the next-morning subjective experience is fine.
• The watch isn't going to flag this as a problem because, by its measures, it isn't one yet. The breathing data is the early warning.

This is, incidentally, a big part of why "I feel fine, my watch says I'm fine" doesn't rule out OSA. The watch is honest about what it can see. What it can't see is whether your airway was closing in the dark while everything else stayed within bounds.

Why both can be low

The reverse case — low sleep score, low BRI — is also informative. If your breathing was clean (BRI under 5) and your watch still says you slept poorly, the disruption was something other than breathing. Stress, anxiety, noise, partner movement, alcohol's effect on heart rate without affecting the airway. These are different problems with different fixes. Knowing your breathing wasn't the issue narrows the search.

This is where two devices reading the same night actually do useful work. Either alone, you'd guess. Together, you can rule things in and out.

How to read them together

One night of either device is anecdote. A pattern over a month is signal. If you're going to take one of these conversations to a clinic, take the month of evidence, not the individual night.