How Sleep and Fitness Trackers Work, and Whether They’re Worth It

https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr-768x432.jpg 768w, https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr-640x360.jpg 640w, https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr-223x126.jpg 223w, https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr-106x59.jpg 106w, https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr-348x196.jpg 348w, https://www.extremetech.com/wp-content/uploads/2019/03/565284-fitbit-alta-hr.jpg 810w" sizes="(max-width: 300px) 100vw, 300px" /> Once something only for those obsessed with fitness, health trackers of all types are becoming commonplace and are a key part of the ongoing revolution in digital health technology. We