Sleep trackers are everywhere today. You can find them in standalone wearable devices, smartphones, smartwatches, and fitness trackers. Some apps can give you information about hours of continuous sleep, how much time you spent in each sleep cycle, sleep quality, and sleep efficiency, among other data. But how accurate are these commercial sleep trackers, and how useful is the data in analyzing our sleep habits?
The Difficulty of Assessing Sleep Trackers
We live in an ever-advancing technological age. As soon as any new technology has been developed, its replacement or upgrade is already being prepared. This constant advancement means that often by the time researchers can set up a study, some of the consumer sleep trackers they are testing have been discontinued.
However, it is still important to assess their accuracy. According to a 2019 Gallup survey, 19% of Americans use a wearable activity tracker, and the same number use a mobile health app. More than one in four Americans use one or the other, and around 10% actively use both. When this data was combined with past statistics, the survey concluded that 34% of Americans at some point had worn a fitness tracker or smartwatch to monitor their health. Additionally, 32% had tracked their statistics through an app.
Testing Sleep Trackers
In 2020, a study into wearable sleep tracker efficiency by a team of neuroscientists at West Virginia University (WVU) was published in the journal Nature and Science of Sleep. The study involved five adults wearing nine popular commercial sleep trackers for a period of 98 consecutive nights of sleep, as well as a standard electroencephalography (EEG)-based medical device typically used to assess sleep. The trackers’ results were then looked at in direct comparison to the data from the EEG device to assess their level of accuracy. Seven out of the nine trackers either over or underestimated at least one of the sleep metrics they were recording. None of them appeared to record sleep stages accurately.
Why Sleep Trackers Are Not Always Accurate
Sleep trackers are still not as accurate as they could be in assessing your sleep time, mainly based on how they gather their data. Most consumer devices and apps rely on monitoring your body movement when lying down instead of assessing whether you are asleep. They base this on a set of predetermined algorithms programmed into the device. Suppose you are a person who tends to lie very still in bed or you have an abnormal sleep pattern or routine. In that case, your tracker or app may not be able to factor this in and differentiate between being awake and asleep. All this means that the data is often nothing more than an educated “guesstimate” of both how many hours of sleep you are getting and the quality of sleep time.
More people are supposedly getting an insight into their sleep patterns as usage of sleep trackers and apps increases. However, when the data is not completely accurate, it leads to an upswing of people claiming they have a sleep disorder and seeking treatment for self-diagnosed sleep issues.
Research on this phenomenon was conducted by a team of sleep researchers from Rush University Medical College and Northwestern University’s Feinberg School of Medicine. As part of their study, they came up with the term “orthosomnia” to describe a person obsessed with perfecting their wearable sleep data. After looking at three separate case studies, the team found that an obsession with perfecting their tracker’s sleep score raised levels of sleep anxiety. Insomnia levels also appeared to rise as people tried to spend more time in bed to increase their sleep duration despite evidence of the trackers overestimating sleep. One of the more significant outcomes of the cases studied was how much people believe the data from a wearable sleep tracker to be generally accurate. This belief does not completely change, even when a controlled sleep study contradicts it.
Sleep trackers and wearable technology are a growing part of our daily lives, and their popularity is only increasing. If you are someone who uses one, it is worth seeing the data they produce as giving you an insight into how you are sleeping. Tracking your sleep with one of the many available smart devices can allow you to compare one night’s sleep to another based on the same parameters.
If you are concerned about your sleep behaviors or getting good quality sleep, the best option is still to speak to your doctor or healthcare professional.