How does the armband track sleep?

A sleep analysis is performed on your armband data by comparing it to examples that were collected in a sleep lab. Patients wore the sleep lab's polysomography monitor (PSG) and the armband. Every minute through the night the PSG monitor and sleep lab staff recorded sleep or wake (plus other clinical measure every 30 seconds). The armband system contains the statistics and patterns that match the armband sensor readings and sequences to the results from PSG.  The armband's sleep analysis requires you to be lying down sleeping, and may not work if you sleep in a chair.