Sleep Start
Or myoclonic jerk.
It can sometimes happen just before people enter a deep sleep, no one is completely sure why it happens but the leading theories are that as your muscles relax you brain is fooled into thinking it is falling and wakes you abruptly so you can catch yourself. This may also have something to do with the fact that you may not be in a place where sleep is normal or allowed and your brain knows this, so the logical conclusion based on that, is that you would be falling.
Many fewer people report this sensation in bed, it is usually reported when falling asleep somewhere else.
Excessive entertainment the night before.
The preposition in the sentence is "during." It shows the relationship between the action of falling asleep and the noun "class."
Maybe they have extra curricular activities every night.
No, it is a reason to take caffeine.
Nearly falling asleep in the middle of my class and my teacher screaming at me.
Well, have you ever been in class and felt real drowsy and started to fall asleep? Then right before you do, your body kinda jerks and you catch yourself.
fall asleep
"Class was so boring that I fell asleep."
It is the class frequency.
your going fall asleep
Well, first of all it is the MAGNA CARTA, not the carta magna. So open up your history book and stop falling asleep in class you ignorant middle schooler!
staying awake in class and reading your course materials