An estimated one in three people report regular sleep complaints. So it’s hardly surprising people are more concerned than ever about getting enough sleep. This blossoming interest has seen an explosion of sleep trackers which measure how many hours of sleep you get each night. But these devices may not be as accurate or useful as they claim.
As we sleep, we go through cycles of “deep”, “light” and “rapid eye movement” (REM) sleep. The “deep” portion of our sleep is mainly what leaves us feeling refreshed the next day. Most sleep trackers are a watch worn on the wrist, and work by monitoring your body movements as you sleep to determine how much time you probably spent awake versus asleep. Some devices also look at heart rate changes during sleeping to estimate how much time you spent in each sleep cycle.
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