Maybe he and Karen had another late night talk marathon after the Roy incident.

nope...i think its his hair. it's definitely different. he must have cut it for a movie or somethin' and they used a hairpiece or somethin'. too bad to, cause he looks a bit dorkier, don't you think?

I think dorky is cute on Jim, so, I'm impartial. =)

I think the "exotic" Karen is wearing him out!
In The Negotiation, before Roy comes into the office, Karen is giving Jim a hard time about not wanting to go to the movies. She says something to the effect that he would rather sit on the couch all night watching a Phillies game than go out. You can see the look on Pams face where she's thinking "I'd like to spend the evening on the couch with Jim watching the game". I think Jimbo is growing tired of Karen and is trying not to end up like Ryan.

God I need a life!

I think that it was because it was a friday...having to deal with michael scott for 5 days straight would make me look a bit tired too.

Jan: Last Friday, one of your employees attacked another employee in your office.

I think they are trying to show Jim is getting wore out with Karen and work, and is just really not as happy as he used to be.

John krasinski is shooting a movie and at the same time he's shooting the office. jim might not have actually been tired but john was probably tired from working so much and it showed up on his face. either way it still worked for him.

John/Jim has about four films in the works at the moment, most notably "Leatherheads" with George Clooney, about pro football in the 1920s. Definitely shaved his head for the part and is definitely wearing a wig.

Aw, I like John's hair! If I see the George Clooney movie, it'll be so weird to see him bald.

The wig's not really obvious, so that's good.