A study from the University of Pennsylvania this week said that in study subjects -- who smoked -- which were deprived of nicotine ended up showing activated levels of craving activity in their brains related to cravings.

In other words, just like those "Cravings" for chocolate or any other vice, smokers may have a "craving" for nicotine that could overwhelm the logic of "I don't need to smoke" and into the emotion of "I need my next fix" -- or something similar.

Combined with the psychological effects of those who crave cigarettes, this study is one of the first to show the physical effects of such a craving and how, neurologically, the brain can indeed effect the need for that next smoke.