Can fitness trackers diagnose your sleep disorder?

If you have a fitness tracker, you probably wear it all day, every day to make sure you get an accurate count of your steps and heart rate measure, but there’s a good reason to leave it on while you’re catching some zzz’s, too: It turns out many wearables can also diagnose a common sleep disorder.

According to a new study, researchers found the Apple Watch to be particularly adept at detecting sleep apnea. In fact, it had a 90 percent accuracy rate with the 6,115 participants involved—just based on the wearers’ heart rates. Because the condition affects nearly 22 million people nationwide—and can be life-threatening—this function of fitness trackers could make a huge difference in the 80 percent of cases left undiagnosed.

“What if we could transform wearables people already own—Apple Watches, Android Wears, Garmins, and Fitbits—into inexpensive, everyday screening tools using artificial intelligence?” —Brandon Ballinger, study co-author

“What if we could transform wearables people already own—Apple Watches, Android Wears, Garmins, and Fitbits—into inexpensive, everyday screening tools using artificial intelligence?” study co-author Brandon Ballinger wrote in a Medium post. “Within the US alone, sleep apnea [drives] $150 billion in direct medical spend, lost productivity, and accidents.”

So pay close attention to your tracker—the data it spits out on the daily could end up keeping you healthy in more ways than you might’ve originally thought.

Here’s how to know whether your fitness tracker is really working. Also, take a look at this futuristic jump rope that’s part fitness tracker.