Knowledge is power—and when it comes to sleep, many of us assume the more we know about our habits and patterns, the more power we’ll have to improve our ZZZs. But measuring the quality of your shut-eye isn't quite so simple. After all, the accuracy of data collected by sleep trackers isn't necessarily accurate—and even if it was, that doesn't mean it would help you optimize your sleep.
Earlier this year, a study in the Journal of Clinical Sleep Medicine examined the real-world effects of using sleep trackers. In a series of case studies, the researchers found trackers were unlikely to help people achieve better sleep. In most cases, they actually seemed to make things worse.
“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.
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.
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.)
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.
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.”
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.”
Some may argue that healthy sleep patterns are more likely to develop when you're not focusing so much on it. Overanalyzing sleep could lead you to think about it more when you climb into bed, which in turn could lead to problems drifting off.
“Overall, I think a large number of people need to sleep more, so I’m glad people are getting interested in improving sleep,” Baron says. But, she adds, it’s not clear what sort of person would benefit most from using a sleep tracker.
“I think your average, stressed out, over-worked person who doesn’t pay enough attention to the amount of sleep they’re getting could benefit if a tracker helped them realize they needed more,” she adds. “But again, there’s no data on that.”
There’s no doubt that many Americans need more sleep. A recent National Safety Council report found that half of Americans are sleep deprived.
But rather than carefully tracking our sleep habits, most of us need to focus on improving them.
“I think setting a consistent bedtime, and giving yourself time to transition before bed without a screen is helpful,” Baron says. “Not watching that extra show so you can go to bed 15 or 30 minutes earlier is probably going to help.”
Some of these sleep tracking apps offer ways to record your pre-bedtime habits—what you ate or drank, or watched or read, right before bed on nights when you slept poorly. That could help you recognize stuff you're doing that messes with your sleep.
Baron also recommends talking to your spouse or partner about wanting to get more sleep, and turning the light off a little earlier.
She adds, “I don’t think you need another piece of electronics to help you with sleep."