https://www.sciencedaily.com/releases/2021/02/210217151008.htm

And like any consumer products, not all sleep trackers are created equal, according to West Virginia University neuroscientists.

Prompted by a lack of independent, third-party evaluations of these devices, a research team led by Joshua Hagen, director of the Human Performance Innovation Center at the WVU Rockefeller Neuroscience Institute, tested the efficacy of eight commercial sleep trackers.