Western Pennsylvanians changed the clocks a few weeks ago and lost an hour of sleep, so it may be fitting that March is Sleep Awareness Month.

The benefits of getting enough or not too much sleep are all around, but how does anyone really know if they are getting restful, beneficial sleep?

One idea is to wear a sleep tracking device and some wearable tech devices like Fitbits and Apple Watches come equipped with sleep tracking capabilities.

But do they really work and which ones work best?

Researchers at West Virginia University set out to answer those questions and put the devices to the test.

A team of neuroscientists at WVU was prompted by a lack of independent, third-party evaluations of sleep trackers. Joshua Hagen, director of the Human Performance Innovation Center at the WVU Rockefeller Neuroscience Institute, tested the efficacy of eight commercial sleep trackers and published the team’s findings in the journal Nature and Science of Sleep.

Researchers observed five healthy adults – two males, ages 26 and 41, and three females, ages 22, 23 and 27 – who participated by wearing the sleep trackers for a combined total of 98 nights.

“Sleep is one of the most important factors for health and performance and is slowly but surely becoming an easily trackable metric to consumers and athletes alike,” Hagen said.

“So while devices that can measure this are now extremely common, that data is only actionable if it’s accurate. There are no regulations for consumer devices as there are for medical, so we feel like it’s an obligation to our customers – athletes, military, patients – to scientifically assess the accuracy of these devices.”

What did they discover?

Trackers made by Fitbit and Oura came out on top in measuring total time asleep, total time awake and sleep efficiency, the study said.

All of the other devices tested either overestimated or underestimated at least one of those sleep metrics and none of the eight could quantify sleep stages – REM, non-REM – with effective accuracy to be useful when compared to an electroencephalogram (EEG) which records electrical activity in the brain, the study said.

“Our main takeaway is that consumer sleep trackers have wide variations in accuracy, so care should be taken when selecting a device,” Hagen said. “Very broadly, most devices can be fairly reliable when looking at total amounts of sleep but are not yet trustworthy for sleep staging information, such as REM and deep sleep. Those metrics require technologies that can measure brain activity, which cannot be done on the wrist.”

In conducting its research, the WVU team took a unique approach where scientists didn’t look to make any scientific insights on the sleep patterns of each individual. Instead, researchers said they focused on looking to see how the data from the devices was similar or different to a “gold standard” device.

Researchers concluded most devices can effectively tell you reliable information about the metrics that you can likely control – like what time you go to bed, what time you wake up.

Hagen said that is an important step when it comes to getting restful, restorative sleep.

“When it’s within your control, aim to go to bed and wake up within 30 minutes of the same time every day and you’ll gain benefits from your circadian rhythm,” he said. “Another metric that can be trusted in some devices is the amount of actual sleep you get and the efficiency of that sleep, which is simply the amount of time asleep divided by the total time in bed. “

Hagen said many daily choices can alter these numbers, like late night caffeine consumption, a busy mind and spending time on digital screens before bed.

Hagen doesn’t stop at just the data from test subject. He actually tests the trackers himself each night.

“So my best use of these devices, I wear four to five different ones every night, is to aim to understand the link between my choices and good sleep data,” he said. “For instance, having an alcoholic drink or two at night may not feel like it affects you negatively, but once you see how it greatly affects your heart rate and sleep quality, it may motivate you to make different choices.”

His advice for choosing a sleep tracker?

“When selecting a sleep sensor, a combination of data quality and form factor is the best bet,” Hagen said. “From our studies, we found that FitBit and Oura performed very well. So to take that as an example, if both have good data quality, then the question is, do you want to wear a watch or a ring? Whatever makes you most likely to wear it day in and day out is the way to go.”

The biggest takeaway from the study is not all consumer devices are created equal.

“Some devices are currently performing well for total sleep time and sleep efficiency,” Hagen said, “but the community at large seems to still struggle with sleep staging (deep, REM, light). This is not surprising, since typically brain waves are needed to properly measure this. However, when thinking about what you generally have control over with your sleep – time to bed, time in bed, choices before bed that impact sleep efficiency – these can be accurately measured in some devices.”


Kristin Emery is a meteorologist at KDKA-TV in Pittsburgh, an O-R columnist, and writer for Total Health magazine and other publications. Kristin is a Washington native and a graduate of Washington High School and West Virginia University.

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