Doctors, what are the effects of nicotine withdrawal?

They vary a lot: But most people get some version of "nicotine fits" - anxiety, agitation, short-temper, difficulty concentrating and strong cravings for a cigarette. Sleep may be adversely impacted, and there may be decreased mood to the point of clinical depression. Nicotine replacement therapy or Chantix (varenicline) can signicantly decrease these symptoms, as can bupropion (zyban, wellbutrin). Support help!