“It’s clear some people take it too far, and become a little obsessed with making their sleep perfect,” says Kelly Glaser Baron, PhD, first author of the study and an assistant professor of behavioral sciences at Rush Medical College in Chicago.
In her study, Baron and her colleagues wrote about one man who felt that if he did not log eight hours of sleep each night on his tracking app, he would likely be wiped out and unable to function properly the following day. (Here are 5 signs that fitness tracking has become bad for your health.)
The man was averaging 7:45 hours of sleep each night, but the stress of trying to hit his eight-hour goal seemed to be doing more harm than good, Baron says. “He was lying in bed even when he wasn’t tired, and doing other things that really weren’t helpful,” she says.
Can You Trust a Tracker’s Data?
While sleep trackers are getting better and more accurate all the time, Baron says several studies suggest many tracking apps and wearables make mistakes.
“Most can’t tell the difference between light and deep sleep,” she says. “People come into the lab with data saying they’re not getting any deep sleep, and that’s not the case based on what we see in their EEG readings.” (An EEG, or electroencephalogram, is a test that measures electrical activity in your brain in order to shed light on behaviors like sleep and conditions like epilepsy, says the Mayo Clinic.)
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In fact, Baron says, many trackers “don’t come close” to accurately measuring sleep—often because they misinterpret small wrist movements as signs of light sleep or wakefulness.
“Movement detection at the wrist can’t [determine] what’s going on with brain waves,” she adds.
Even If The Data Is Accurate, Is It Helpful?
To date, there is no evidence that using a sleep tracker improves a person’s sleep.
A 2015 study in the journal Sleep found “a critical absence of supporting evidence for the advertised functions and benefits in the majority of the devices.” (Psst! Here are 8 things your sleep habits say about you.)
Especially for those who already struggle to fall asleep or who feel anxious about getting enough rest at night, a sleep tracker may exacerbate that anxiety, Baron says. In her study, she writes that trackers may “reinforce sleep-related anxiety or perfectionism for some patients.”