A recent study in Psychopharmacology Bulletin shows that nicotine withdrawal impairs time perception. Laura Cousino Klein and colleagues from Penn State University suggest that the tendency for smokers to overestimate the duration of short intervals after just 24 hours without a cigarette contributes to the anxiety and concentration difficulties that beset those who try to kick the habit.

In a small experiment with 44 subjects, Klein's team had smokers and non-smokers assess the duration of a 45-second interval. Prior to nicotine withdrawal, the smokers' responses did not differ significantly from those of the non-smokers — both groups made similarly accurate estimations, with an error range of about 5 seconds. However, after foregoing tobacco for 24 hours, smokers overestimated the amount of time that had elapsed, by 50% on average. “We had some people [who] thought it was three minutes”, Klein told The Associated Press.

To smokers who have tried to quit, these findings come as no surprise. A student at Penn State in the throes of withdrawal lamented that “When I'm sitting, when I'm bored ... one minute passes and it seems like five” (Post-Gazette, USA, 14 May 2003). But encouragement to tough it out came from a spokeswoman for the UK charity Action for Smoking and Health who pointed out that “These sort of feelings are over very quickly. Nicotine leaves the blood within 48 hours so it should get much easier after two days” (BBC News, UK, 10 May 2003). Smokers be warned — according to the new study, those two days will feel more like three.