If you’ve spent any time in Best Buy, you’ve probably seen the burgeoning market of fitness and #sleep trackers. These devices strap onto your wrist and track calories burned, distance run, and how well you sleep.
But have you ever wondered how a little device on your wrist can track the quality of your sleep? Let’s take a look at the history and science of sleep tracking.
Sleep scientists have relied on two scientific techniques for determining a person’s sleep state. The first is known as polysomnography, and it attaches more than 20 receptors to the user’s body. These receptors track a variety of factors, from limb movement to breathing patterns to heart rate, using these factors to asses the quality of your sleep.
This method was developed in the 1960s when a group of scientists looking to treat #sleep apnea began searching for better ways to track rapid-eye movement, or REM sleep, which they had only recently discovered. They also needed a test that could be set up and run all night so the scientists searching for a cure for sleeplessness wouldn’t have to sacrifice their own sleep for the cause. To this end, scientists constructed the polysomnogram, a machine that uses 12 data channels and 22 accessories to track the user’s sleep state, and most crucially has strap-on sensors that enabled the scientists to leave the patient alone overnight and head home to their warm beds.
The second method of tracking sleep is known as Actigraphy, It places a small watch-based sensor on the trackee’s wrist, and tracks movement. This sensor, also known as an accelerometer, sends the data to a corresponding app, which compares it with standardized sleep cycle data from the public.
The technology was developed by the military in the 1980s to track the sleep patterns of soldiers in the field. As technology prices decreased and the FDA approved the technology for consumer use, and companies like FitBit and Jawbone began building cheaper versions that the everyday user can wear on a daily basis.
Most trackers rely on Actigraphy. In other words, it’s only thanks to THE U.S. Military that across the world, consumers can strap on a device, download an app, and learn how their sleep cycle compares with that of the general population.