Question

why do people fall asleep unknowingly during their study time?

Answer 1

It is not true for all but true for some

some people do not have fun studying which bore them and makes their mind lazy . Due to that laziness makes them sleep. you can also notice the time when you don't have anything to do , at that time you sleep.

there Can be one more reason that the light or bulb that they use, may irritate their eyes and mind