Episode 39

Consumer Sleep Trackers

Consumer sleep trackers are all the rage these days, from Fitbit to Oura ring to tons in between. So what are these devices and what do they actually tell us?

In this episode, I explore the ever-expanding landscape of non-medical, consumer grade sleep tracking technologies.

There are a lot of devices in the consumer market that make all kinds of claims about your sleep, and measuring and decoding your sleep using secret proprietary algorithms they won’t share with anyone. And when put to the test, they are not terrible. But they’re not that great either.

Motion-based sensors have an accuracy in the 80s percent or less. Step up to the next gen multi sensor devices that incorporate photoplethysmography to calculate heart rate and heart rate variability, and that accuracy for distinguishing wake vs sleep creeps into the 90s - but only as long as you're a normal sleeper. Any difficulty with sleep (whether you’re aware of it or not) and that accuracy plummets. And claims about detecting light vs deep vs REM sleep are about as accurate as a flip of the coin.

But these devices could also revolutionize healthcare. Because a long term track record of physiological data - as imperfect as it is - could expand the reach of sleep as a biomarker, sleep as a vital sign - sleep and changes in sleep over time as predictive of disease. We’ve already seen that happen with the pandemic - that retrospective analysis of multi sensor sleep tracker devices was able to predict with fair accuracy COVID-19 a couple days before symptom onset based on changes in heart rate, respiratory rate, skin temperature, and sleep. They have a long way to go, but they could be very important in population health and the future of personalized medicine.