Participants in this 12-day dose escalation study will be tested under eight different dose conditions. Modafinil and NRT will first be tested alone; participants will be exposed to low doses prior to higher doses of medication. Various modafinil-NRT dose combinations will then be tested. Modafinil will be administered at 5 p.m. each day, and NRT will be self-administered at the start of each day in which a participant must complete lab tests. The following measures will be obtained at study visits occurring before and after the various modafinil-NRT dose combinations: nicotine withdrawal symptoms, medication side effects, activity level, cardiovascular response, and profile of mood states (POMS).