Some students don't ever get any sleep due to extra curricular activities, homework, housework, and yes, poor choices as well. And on top of it, many students have problematic stresses with his or her family at home.
As a result of this, students feel hurt or angry at teachers when they get upset with them for not being able to stay awake in class; just another way of solidifying that dreadful relationship between the problematic student, and the irritated teacher.
Teachers are always getting mad or irritated at students when they fall in sleep in class. Obviously, teachers have a job to hold on to;
one of the ways to help insure that job is to keep their class grades successful and high. This goal is hard to realize when student are sleeping in class and aren't actively learning. Also, most teachers (whether students believe it or not) care for their student's future and wish to see them succeed in their future life; if they don't care, they're in the long line of work. This personality often leads to a huge misunderstanding between the student and the teacher, causing huge conflict between them.
After all is said and done, we need to stop viewing sleeping in class as a problem and learn to identify, brainstorm, then solve this life issue by finding a common ground between student and teacher as equals in a society instead of being reprimanded; after all, we all live diverse lives on which need to be treated diversely to ensure individual success in a community.