If he's disrupting your sleep and studies then chances are he's probably annoying your other neighbors as well, especially if the halls small like weed. I'd recommend telling him about it before reporting him. Give him a chance to stop on his own, he may not realize that anyone is being disturbed; some people are oblivious to the fact that dorm rooms aren't insulated and soundproof. If it continues then you should report it because there's no reason to just ignore stuff like that. Definitely give him a chance first and ask him to quiet down or smoke weed some place other than the dorm.