The rise of sleep-tracking wearables prompts CNET to explain the differences between sleep stages.

Light sleep is the beginning of your sleep cycle and your body’s way of winding down. Breathing, heart rate and muscle changes prepare your body for the deeper sleep to come.

Light sleep is broken down into stages 1 and 2. The first stage is simply the act of transitioning from awake to asleep and makes up less than 3 percent of your nightly sleep cycles.