Many people claim that they smoke because it "reduces stress". Well it turns out that smoking does reduce stress...the stress of not smoking that is. It doesn't seem to actually help with other causes of stress.
From the New York Times column "The Examiner".
The claim: Smoking relieves stress.
The benefits of quitting smoking - reduced risk of cancer and many other health problems - are known. But for millions of smokers, the calming effect of a cigarette can be reason enough to start up again.
Studies have found, however, that in reality, lighting up has the opposite effect, causing long-term stress levels to rise. For those dependent on smoking, the only stress it relieves is the withdrawal between cigarettes.
In a recent study conducted at the London School of Medicine and Dentistry, researchers looked at 469 people who tried to quit after being hospitalized for heart disease. At the start, the subjects had similar levels of stress and generally believed that smoking helped them to cope.
A year later, 41 percent had managed to stay abstinent. After controlling for several factors, the scientists found that the abstainers had "a significantly larger decrease in perceived stress," roughly a 20 percent drop, compared with the continuing smokers, who showed little change.
The scientists' hypothesis was that the continuing smokers were dealing with uncomfortable cravings between cigarettes multiple times a day, while the abstainers, after facing some initial withdrawal, had greater freedom from nicotine cravings and thus had eliminated a frequent and significant source of stress.
Other studies have also found that smokers experience higher levels of stress and tension between cigarettes and lower levels overall when they quit.
The bottom line: The calming effect of a cigarette is a myth, at least in the long term.