Fitness trackers and sleep apps: when numbers stress you more than they help
You wake up and reach for your phone before you're even properly awake. A number decides how your day begins. Sleep score: 62. Poor sleep, the app says. But you actually felt rested.
What activity trackers actually do
That trackers increase movement is well established. A meta-analysis of 39 studies with more than 160,000 participants found an overall positive effect. People who use trackers take more steps, and other research confirms this too.
What matters more is how long the effect lasts. Together, 70 studies show: about 1,100 more steps a day after four months, still around 1,050 after six months, only 464 after a year, and barely anything after two years. Whether that's down to the well-known novelty effect or simply because any behavior change gets harder to sustain over time isn't something the numbers alone can settle. On average, there is an effect, but it gets smaller. How fast varies from person to person.
When sleep itself becomes a task
With sleep, the research is much younger and more fragmented. In 2017, sleep physician Kelly Baron and colleagues described three cases from their own practice and named the phenomenon orthosomnia, modeled on orthorexia, the compulsive fixation on "correct" eating.
The three patients had different sleep problems, some already known. On top of that came a fixation on the tracker data that, in the end, occupied them more than sleep itself. Even the researchers couldn't say at the time whether the fixation triggered the problems or just made them worse.
This has since grown into a research field of its own. In 2025, the Bergen Orthosomnia Scale became the first measurement tool for it: it shows links to sleep effort, mistaken beliefs about "correct" sleep, and perfectionism. A study of more than 500 people found, depending on the definition used, 3 to 14 percent with notable scores. A smaller study of insomnia patients in 2023, by contrast, found no clear worsening from tracker use. So it doesn't affect everyone the same way.
Two effects, differently supported by evidence
The effect of trackers on movement is well supported by many large studies; the only real uncertainty is why the effect fades over time.
Orthosomnia is younger. It started with three described cases; there's still no recognized diagnosis, though there's now a dedicated, validated measurement tool. What's mainly still open is who sleep trackers actually trigger the phenomenon in: people already prone to sleep-related worry may be more likely to reach for a tracker in the first place.
The mechanism behind it is already known from sleep research: when you consciously try to force sleep, it often raises your baseline arousal, known in sleep research as hyperarousal. A tracker adds fuel to that, because it hands you a new, seemingly objective target every morning.
What's behind the need for control
Psychoanalyst Benigna Gerisch, together with Vera King and Hartmut Rosa, examined where the urge to rely so heavily on numbers comes from. Their project on the "measured life" surveyed around 1,000 people, 64 of them in in-depth interviews.
When tracker data and your own sense of things don't match, it often creates unease. You feel rested; the app reports poor sleep. Gerisch sees this as an attempt to make inner processes controllable that resist exactly that kind of control.
Trust your body at least as much as your screen
A tracker shows you patterns over weeks that you'd otherwise miss. That's exactly where its value lies. It gets difficult when the numbers become more important than what your body is telling you right now.
In my sessions, I therefore advise clients to put the tracker aside for a few days now and then and pay attention to their own signals directly instead: how a muscle feels, how rested you really are, with no number in between.
Researchers call this interoception, the sensing of internal bodily signals. It can be trained; early studies show positive effects from practices such as mindfulness exercises. To me, that's exactly what vitality means: learning again to notice more clearly what your body is telling you.