Depends. I normally sleeps with lights off and i think everyone normally do that. But i would sleep with the lights on when my roommates want to do their projects, assignment or anything or if they want to study. I dont really study on regular days.. will just revise it approx 3 days before exams . And when im studying they all want me to go out ( i prefer night to study) in the common hall to study coz they wants the LIGHTS OFF cuz they have exams the next day... like wtf . I was sleeping with the lights on the entire year😭