Hi--
When I quit, (15 months ago) I did use Wellbutrin, (same thing as Zyban). It did keep me awake at night. And one good side effect was it supressed my appetite, which I liked. I only took it for 3 weeks, because I really needed some sleep. But I was also using nicotene patches, so I was fine. You're probably feeling tired from the nicotene withdrawl, (it's a stimulant) and from not sleeping well. Hang in there, and congratulations on quitting smoking..that's great!

Deda