Simply wear the Spark and let it keep track of your movements. As you move, the Spark will calculate your average motion.
Using motion sensors and an internal algorithm, the Spark will detect that you have fallen asleep when your average motion decreases significantly.
The tech that senses your movement.
The science that calculates your motion frequency.
The part that keeps you awake.
The screen that displays the time and mode.
The band that keeps the watch on your wrist.