The watch that keeps you awake

Can someone explain how this works? On the site it does't mention how it wakes you up. sound? vibration?
@johnnyquachy Spark depends on motion tracking to detect when you doze off. A gentle vibration reminds you to wake back up. hope this helps!
This is a cool product @eddy_zhong! Do you have any testimonies of people saying it's helped them stay awake in school and such? Also, I heard you recently dropped out of high school -- what spurred this decision?
@tzhongg There's never enough time for school :) And yes, we have testimonials.
Let me know if you have any other questions.