Doing things changes things

I'm a sleeping guy, espcially in classes.
I am wondering that is it a physical or emotional problem?

"Sleeping Beauty" was a nickname given by my classmates in cram school.
I don't want to always doze off, because sleeping in class actually wastes my time.
It let me spend more time on studying than other ones who can concentrate on in class.

Today, in my emt-1 class, I slept again and again during the whole day.
Oh, I really want to be a good student in every class!