If you tend to drink a lot of coffee and cola during the week, but take a break from them during the weekend, you may experience headaches of caffeine withdrawal. Nicotine is another popular stimulant, usually taken by smoking and absorption by the lungs. Nicotine is a stimulant of central nervous system activity, but it does relax muscle tone slightly, which may explain the rationalization of smokers who claim that they can relax by having a cup of coffee and a cigarette. Indeed, beginning smokers generally cannot smoke more than one or two cigarettes without becoming ill. The drug often leads to dependency.
More recent reports blame tobacco use for nearly half of all deaths in the United States.
We'll return to issues of smoking and nicotine addiction in our discussion of health psychology in Chapter 11. There are many physiological reactions that result from cocaine use. It elevates blood pressure and heart rate. This means that once these neurotransmitters have entered a synapse, cocaine will prohibit their being taken back up into the neuron from which they have been released. The result is that, for a time at least, excessive amounts of the neurotransmitters are available in the nervous system.