What Do Sleep Trackers Track?
Published December 2021
A Sleep Tracking True or False
Nothing beats a good night’s sleep, but if you’re having difficulty sleeping, you wouldn’t be alone in turning to a high tech wristwatch or smartphone app. Depending on what you’re looking to learn, sleep trackers might not be giving you an accurate picture of your nightly Z’s - and knowing what the tracker is really measuring can put your mind at ease.
Phyllis Zee, MD, director of Northwestern Memorial Hospital Sleep Disorders Center, explains what sleep trackers do and do not track.
Sleep trackers use an accelerometer, a device that measures how much you move while you slumber. This data goes into an algorithm to estimate the amount of time you sleep, and the quality of your sleep.
Sleep Stages: False
Some devices claim to measure sleep stages, but this isn’t necessarily accurate. Body indicators such as brain wave activity, eye movement and muscle activity measure the four stages of sleep and devices monitor body or wrist movements.
For the most accurate measurement of the stages of sleep, you need to measure sleep and not just lack of movement. This can be done as a sleep test at home, in a laboratory setting or sleep center.
Many sleep trackers haven’t been scientifically evaluated or approved by the FDA, but that doesn’t mean a sleep tracker can’t help you maximize your nightly shuteye.
“Just like activity trackers, a sleep tracker can help promote a healthier lifestyle. It gives you a visual for how well you adhere to your sleep and activity goals, and helps you to be more self-aware,” says Dr. Zee.
Sleep Disorders: False
The activity tracker isn’t going to detect sleep apnea, insomnia, or any other sleep disorder, cautions Dr. Zee.
“Using a tracker can help you recognize patterns. However, for a person with a sleep disorder, the tracker can give false reassurance that everything is OK, or create more anxiety. A tracker can only tell you so much,” she says.
Awake or Asleep: Somewhat True
Most trackers can estimate when a person is awake or asleep. However, there is a degree of error. Each sleep tracker has a different degree of sensitivity to your movements, and even the algorithms can greatly affect the accuracy of the data collected. The slightest movement by your spouse or even a pet could move the device, too.
Sleep is an important part of your physical and emotional health. For most adults, it takes eight to 10 hours for your body to continuously cycle through the stages of sleep three to four times for optimum sleep. Trackers can help you monitor your healthy sleep habits, but, if think you have a sleep disorder, your best bet is to talk to your physician as soon as possible.