The Amazfit tracker has the capability of measuring sleep patterns, which users can see on the phone app as indicated in the light and deep sleep bar charts. The tracker measures the movement of the user though a typical sleep cycle, which consist of five stages of sleep. Each sleep cycle is roughly 90 minutes, where a person will flow in between cycles. The tracker does not measure actual sleep cycles (i.e. Phase 1 - Phase 5) but records an individual's sleep activity through movement.
The easiest way to under the difference between light and deep sleep can be described as the following:
LIGHT SLEEP: when you move more
This can be described as when your muscles are relaxed, your breathing and heart rate slow down, your body temperature slightly decreases and light dream activity take place.
DEEP SLEEP: when you move less
This can be described as when you breathing and heart rate decelerate further, your body barely moves and dream activity does not take place.