It's because cigarettes have a dopemine release in the brain... similarly to mdma... they feed off of eachother essentially... it's more indepth than that but thats the basics
I know i'm like smoking non-stop all night and at the end i think oh i'll save my last ciggie for when i wake up cause i'll be craving it. And when i do i can't even look at the ciggie! its weird - but i get it when i'm drinking to. And i always have a sore throat the next day
I'd also like an answer set in stone to this question. I try to avoid smoking for the first 12-24 hours of my comedown as the comedown gets all the more harder to deal with when the buzzing comes back each time I smoke!