That was the only thing cigarettes were ever good for! Back when I smoked, if I was stuck on something, I would go have a cigarette. Most of the time I would have the answer (or at least a hint) when I came back in. Some say that nicotine temporarily increases brain function, so I just chalked it up to that.
Many of the advantages of smoking can be chalked up to breath control. Sometime, try standing up, walking around your desk, and pretending like you're smoking. Inhale just as you would a cigarette, but just plain air. It works remarkably well (for me anyway).
For me, what usually happens is I go to sleep, wake up, and have it fixed in 5 minutes.