Smokers often say they need a cigarette to calm their nerves, but a new study suggests that after a person kicks the habit, chronic stress levels may go down.

The findings, say researchers, should give smokers reassurance that quitting will not deprive them of a valuable stress reliever.

In a study of 469 smokers who tried to quit after being hospitalized for heart disease, the researchers found that those who remained abstinent for a year showed a reduction in their perceived stress levels. In contrast, stress levels were essentially unchanged among heart patients who went back to smoking.

The study, reported in the journal Addiction, supports the theory that, at least for some people, smoking actually contributes to chronic stress.

Smokers often see cigarettes as a tool to manage stress, and ex-smokers sometimes return to smoking in the belief that this will help them cope with a stressful life event, lead researcher Peter Hajek, a professor at Barts and The London School of Medicine and Dentistry in the UK, told Reuters Health in an email.

Yet, he said, studies have shown that non-smokers tend to report lower stress levels than smokers do.

The reason for that difference has been unclear, but it could mean that people vulnerable to stress are more likely to take up smoking -- and that taking away that habit could worsen their stress.

On the other hand, smoking itself may generate long-term stress, even if people feel it offers them temporary relief from trying situations.

Hajek's team looked at that question by recruiting 469 smokers who had been hospitalized for a heart attack or heart bypass surgery. While the patients were still in the hospital, they completed surveys on their perceived stress levels and smoking habits. All said they were motivated to quit and had agreed to take part in a clinical trial of in-hospital smoking-cessation counseling.

At the outset, most of the study participants -- about 85 percent -- said they believed that smoking helped them deal with stress to some extent. Half said that the habit very much helped them cope.

One year later, the study participants were surveyed again, at which point 41 percent had managed to remain abstinent.

On average, Hajek and his colleagues found, the abstainers showed a 20 percent reduction in their reported stress levels, while patients who had gone back to smoking showed little change in their perceived stress.

The relationship between abstinence and reduced stress held up when the researchers accounted for factors such as patients' age and education, how heavily they had smoked before quitting, and how high their stress scores had been at the start of the study.

The findings, according to the researchers, support the idea that dependency on cigarettes is itself a chronic source of stress.

When dependent smokers cannot smoke, as the period without cigarettes lengthens they tend to feel more and more edgy, irritable and uncomfortable, Hajek explained. A cigarette relieves this stressful state, and this is probably the main reason smokers think that smoking relieves stress.

So someone who smokes 20 cigarettes per day, for example, essentially goes through 20 bouts of stress each day, as the levels of nicotine in the body decline. Once that person quits -- and gets over the initial period of withdrawal -- he will have 20 fewer periods of stress each day, Hajek said.

Many smokers worry that if they stop smoking, they will lose a valuable tool for coping with difficult situations and stresses in their lives, Hajek noted.

These findings, he said, instead suggest that quitting may not only benefit smokers' physical health, but possibly their mental well-being as well.

United kingdom China Addiction