Nicotine causes pleasant feelings and distracts the smoker from unpleasant feelings. This makes the smoker want to smoke again and continue smoking. Nicotine also acts as a kind of depressant by interfering with the flow of information between nerve cells. Smokers tend to smoke more cigarettes as the nervous system adapts to nicotine. This, in turn, increases the amount of nicotine in the smoker’s blood. Eventually the smoker develops a tolerance to the drug, meaning it takes more nicotine to get the same effect that the smoker used to get from smaller amounts, leading to an increase in smoking.