They don't mean to make you feel guilty - honest. Probably they are very jealous of your ability sleep less. I am happiest with nine hours and start becoming a zombie at somewhere less than seven hours a night. With six hours or less, you honestly don't want to know me, because all I want to do is sleep or cry and I become rather more likely to kill people.

So it's kind of annoying for you to have sleeping roommates, but life is at least equally miserable from the other end.