100 subjects who smoke at least 20 cigarettes per day will come in on two different days, at least one week apart, in a randomized, double blind, within subject, placebo controlled design. On each day subjects will refrain from smoking cigarettes for 8 hours. On one day subjects will take the active DS (taken in two doses, the evening dose is taken at 22:00 of the night before the test day and the morning dose is taken at 8:00 of the test day) and on the other day subjects will take placebo (also taken in two doses at the same time points of the active DS). Mood symptoms and symptoms of cigarette withdrawal will be compared across the two different days. Measures of mood symptom monitoring will include self report on a scale of 1 to 10, standardized rater questions about mood, and 6 hours into withdrawal, a standardized mood induction will be done with mood assessment. Symptoms of cigarette withdrawal will be assessed over the duration of withdrawal with applied standardized rating scales by trained raters. For the first 15 - 30 subjects, on each day, a health assessment of a physical exam and blood work will be completed at the end of the withdrawal period on both test days as well as for the initial assessment appointment.