DEAR MISS MANNERS: I am a college student, and my roommate and I have majorly conflicting sleeping habits. I have declared music as my major and have seven classes that I need to keep on top of, in addition to several rehearsals a week. My days begin at 9 a.m. and sometimes don’t end until 9 p.m. I am up and about all day long, whether it is to go to class, study, practice, do homework or chat online with my friends. She, however, is an “undeclared” student, so she does not have as many classes, and they are not as difficult as mine. She will often sleep all day, even if it means skipping clas…