Can you trust your sleep tracker's score?

On Speaking of Psychology, the American Psychological Association's podcast (episode 387, 2026), host Kim Mills told psychologist Philip Gehrman that her ring sometimes scores a night as poor when she wakes up feeling fine. Was it just making people anxious? Gehrman, who runs a sleep research lab at the University of Pennsylvania, answered that for some people it does, and in that conversation he explained why the score deserves less trust than it gets.

So the worse you sleep, probably the less accurate these devices are.

Philip Gehrman, Speaking of Psychology, 2026

What a tracker measures

Consumer wearables don't measure sleep directly, Gehrman explained. They measure things like movement, heart rate and skin temperature, and use them to estimate when you were asleep. The only direct measure is brain activity, which is what sleep labs record with electrodes on the head.

The research-grade devices he has used since the 1990s publish their validation studies and their methods. Most consumer companies don't, and they keep changing their algorithms, so nobody outside knows exactly how accurate a given device is. What does seem true is that, like research devices, they work best for people who sleep well. Someone lying still and awake in bed looks a lot like someone asleep, so on a bad night a tracker tends to count wakefulness as sleep.

What frustrates him is the morning after. Clients tell him they thought they slept well, but the device said they didn't, so they decide they didn't. A colleague has coined a word, orthosomnia, for people whose sleep gets worse because they become fixated on their tracker data. His advice is to take the numbers with a grain of salt.

A better morning check

The NHS offers a test that needs no device. You may be getting enough sleep if you wake up feeling refreshed, have enough energy to get through the day and can focus on everyday tasks. Gehrman makes a related point in the same episode: people focus on hours, but quality matters too, and how rested you feel during the day is a large part of it.

A tracker can still be useful for noticing patterns, like a bedtime that keeps drifting later. Just don't let one number decide how your day is going to go. And if poor sleep has been going on for weeks and is turning into months, Gehrman's advice is to talk to someone about it rather than wait years, as many of his clients did.

How this fits the Better Sleep program

In the 1h Protocol for Better Sleep, people whose answers point to the Wired pattern, where the mind switches on at lights-out, start by easing off the effort. In the part of the program written for that pattern, you choose up to two well-meant habits to ease off for fourteen nights, and checking a tracker first thing is one of them: give it a rest, or look once a week at most, because a morning score can set the mood for the whole day and it's only an estimate. Your fourteen-night sheet then has you rate your days instead. The first chapter is free: find your sleep pattern.

Source: Speaking of Psychology, Episode 387: Rethinking sleep and mental health, with Philip Gehrman, July 2026 Research: NHS Every Mind Matters, Sleep problems