Sleep trackers promise objectivity, but they may also create a new form of sleep anxiety.

Consumer tracking devices have a margin of error and measure sleep imperfectly, yet they teach us to treat sleep as something that can be scored, judged, and failed.

There is some research to support why this matters. In a 2014 study, researchers manipulated people’s beliefs about how much REM sleep they had received and found that those led to believe they had slept better performed better on cognitive tasks the next day[i]. A 2020 study similarly found that changing people’s perceptions of sleep duration altered next-day cognitive performance, even though the manipulation concerned belief rather than underlying sleep itself.[ii] Perception can sometimes shape functioning alongside, and perhaps apart from, actual sleep.

This helps explain the nocebo effect of sleep tracking. A nocebo occurs when a harmful outcome is produced not by the thing itself, but by the expectation of harm. Once a device tells you that you slept badly, fatigue feels more plausible, irritability easier to confirm, and concentration harder to trust. The number acquires authority before the body has had a chance to speak. In this way, the tracker can do more than record a problem. It can begin to participate in producing it.

Sleep medicine already has a term for the obsessive pursuit of ideal sleep data: orthosomnia. Introduced in a 2017 clinical paper, the term describes a fixation on tracker metrics so intense that it appears to worsen insomnia-like behaviour[iii]. This is what makes sleep trackers more than a neutral tool. They can encourage a relationship to sleep that is fundamentally at odds with sleep itself.

That tension feels especially bleak because sleep has its own eroticism. Good sleep requires the very qualities that will never truly shut down in a constant state of surveillance. It needs softness, lowered vigilance, trust in the body, and a willingness to let go. Tracking disrupts that atmosphere as it reintroduces observation into a state that depends on relinquishing it. 

This is especially worth remembering because consumer sleep trackers are often granted an authority they do not fully deserve. They can be useful, but they are not equivalent to clinical sleep measurement, and their sleep-stage estimates are not infallible.

Research discussed in 2024 also found that how well people felt they had slept predicted next-day positive emotion and life satisfaction more strongly than tracker-measured sleep efficiency[iv]. That does not mean objective sleep is irrelevant. It suggests, rather, that we may be placing too much weight on metrics generated in an uncontrolled environment and treating them as more definitive than they are.

The deeper problem, then, is not only inaccuracy, but sleep tracking teaches people to approach rest with vigilance. Like pleasure, sleep tends to withdraw under pressure. The more aggressively we try to manage it, the more elusive it can become. Sleep trackers sell reassurance through information, but they may instead produce a state in which the sleeper remains psychologically alert and unable to let go.