It's awesome when a tv character goes through a bout of angst. Wah! Immediately that actor's clothing budget is slashed by at least 80% and he's required to cease shaving for the indefinite future.
I will stick with shows through the aftermath of the 'exciting' plot moments purely chanting "come on, come onnnn" during the next episode until BOOM! Yes. There's a beard. I bloody knew there'd be a beard.
It's not enough to wonder "Hey, Nathan Petrelli may be going through a little mental anguish seeing how his brother just exploded." You need the visual indicator that he suddenly looks like a complete and utter bum.
NO BEARD = NO EMOTIONAL PAIN.
Thems the rules.
The word 'crusty' needs to come to mind and fellow actors should stand a little further from him in the frame, not so much because we're supposed to think his character is unstable and might flip out at any point, but more because he probably smells a little bad.