During the lab session, your brain electrical activity will be checked with an electroencephalogram (EEG). To do this, small sensors will be placed on your scalp and face. You should not drink more than 2 cups of coffee or other caffeinated drinks for at least 2½ hours before the session. At the lab session, you may be asked to smoke a cigarette if the doctor thinks it is needed for you to show your normal smoking behavior.