I will keep an eye out for this. So far my wife has not noticed any nicotine withdrawal or deprivation symptoms, though she does state that the vapor is "thinner" than the smoke was. I can imagine that it feels less... substantial since it is a vapor and not millions of tiny particles of ash, tar, and other byproducts of burning material. Personally, I am pleased and proud that she's taking steps to quit. I know that this can be a hard habit to break, and (IMO) any method that puts you on the road to reducing and then eliminating them, that's a good path to be on.