Sleep smartwatches use actigraphy, an accelerometer built in to measure movement. Using what they read, the tracker can determine whether the wearer has had a restless, intermittent night or whether they are sleeping peacefully and relatively still. They also track heart rate, another indicator of a person’s sleep status. Sleep quality was assessed based on the duration of different sleep cycle stages and the sleeper’s heart rate. App usage for the collection generates a chart or visual display indicating when the wearer is sleeping particularly well at night — or when they get the most sleep.

After a cycle of data collection, the tracking device typically processes the sleep data through an algorithm. It displays it in an app to easily view their history, assesses their sleep, and find areas for improvement. Some apps may also offer advice on how to improve sleep based on their findings.