Your wearable activity tracker may not be measuring your sleep accurately, according to a study led by researchers from the UNC Gillings School of Global Public Health in Chapel Hill, North Carolina, and RTI International, a research institute in Durham, North Carolina.
Researchers reviewed 22 published articles studying the ability of Fitbit and Jawbone (two popular brands of activity trackers) to measure steps taken, distance traveled, physical activity, calories burned and sleep.
Several of the studies indicated the step-counting features were accurate, but found that both brands underestimated calories burned and overestimated total time slept. The findings appear in the International Journal of Behavioral Nutrition and Physical Activity.
To make trackers as accurate as possible, the study’s authors suggest people wear their devices in the same position each day.