Nicotine withdrawal symptoms begin just 30 minutes after a smoker takes his last drag, according to researchers.

Science Daily reported Aug. 22 that researchers from the H. Lee Moffitt Cancer Center & Research Institute's Tobacco Research & Intervention Program and the University of South Florida studied a group of 50 pack-a-day smokers. Half the group was allowed to smoke as they normally would, while the others were asked to abstain from smoking for four hours.

The abstainers reported craving symptoms within the first half-hour, and performance on a concentration test declined; at the one-hour mark, participants reported rising anger, and feelings of anxiety, sadness, and more problems concentrating were reported at three hours.

"This study suggests that the typical smoker begins to feel somewhat out-of-sorts within an hour of his or her last cigarette," said lead author Thomas Brandon. "Although they are not yet in the throes of full withdrawal that they would experience after a day without nicotine, they can already perceive that they are not feeling quite right, and that a cigarette would offer temporary relief."

The research appears in the journal Psychopharmacology.

Hendricks, P., Ditre, J., Drobes, D., & Brandon, T. (2006). The early time course of smoking withdrawal effects. Psychopharmacology, 187(3): 385-396.