One problem I have with doctors is that everything is a fucking disorder if it deviates from the mean in any way. There are people who are far more functional and productive following this sleep pattern. I can't imagine going to bed at 11 and waking up at 7 every day.

A thing is called a "disorder" if

1. it makes it hard to function in society; and

2. it can be treated or mediated somehow, so there's a point to having a name for it.

Basically, a "disorder" is a node connecting "symptoms" to "treatments."