Repeating what others have said, but as the person in question. I'm incredibly depressed in the sense that I struggle to find motivation to achieve fairly basic tasks such as laundry, feeding myself, etc + extremely numbed emotions, but I am high functioning through a combination of anxiety and force of will (I'm graduating with a decent GPA from a state school with a job lined up).

It can be highly invisible; in fact, I reckon that it is usually invisible and most only see the extreme cases such as your roommate.