THE NEW YORK TIMES – Shawn McCall, 48, a personal trainer in Waterford, Mich., started tracking his sleep almost six years ago. Mr. McCall said that his Oura Ring — a sleek titanium device that he wears on his ring finger — has revealed how the choices he makes during his waking hours affect his sleep at night.
“It serves as a constant reminder that if I do certain things, like have too much to drink or eat a large meal before bed, I know my heart rate is going to be higher that night and I’ll definitely have less deep sleep,” he said. “It helps keep me accountable.”
The popularity of consumer sleep-tracking technology has grown rapidly in recent years, and that growth is projected to continue.
Led by wearable devices like the Oura, Fitbit and Apple Watch, the market also includes phone-based apps and “nearables,” which are placed on or beside a person’s bed.
While the capability and sophistication of sleep trackers varies, they can record things such as heart rate, movement, body temperature and blood oxygen levels.
Using these data, the trackers claim to offer valuable sleep insights, such as estimates of nightly deep sleep or a total “sleep score” that reflects overall sleep quality.
Experts who study sleep trackers say that while there are some benefits to knowing this data, it can be presented in misleading ways, and they caution that sleep trackers aren’t a cure for insomnia or other sleep disorders.
Here’s what to know about the trackers’ capabilities and limitations.
How They Work
Many wearables collect data using something called photoplethysmography, or PPG.
“There’s this little light on the back of the device that shines into the blood vessels, and it uses the amount of light that is reflected back to estimate things like heart rate and heart rate variability,” said Dr. Cathy Goldstein, a clinical professor of neurology …