Smartwatches have sensors that understand the heart rate variability and detect any movements and orientations in the wrist and translate this data into different stages of sleep. Most of this is done using AI Archit Agarwal, Co-Founder, Crossbeats While buying a sleep tracker: Types of sleep trackers Potential for sleep obsession and anxiety 85-100 A typically good sleep score. These trackers can reveal how lifestyle factors like exercise, diet, and stress levels impact sleep quality.