(Edwardsville, IL) — People who wear fitness trackers like FitBit or Jawbone may be overestimating how much exercise they’re actually getting. Researchers at SIU-Edwardsville studied four of the most popular brands of trackers over the course of the last school year, and found some overestimated the calories burned. The difference was attributed in part to the monitors picking up movements during sleep and considering them activity. Of the bands studied, the Nike Fuelband was most accurate.