Patients who are anxious and stressed about their operations are likely to take much longer to recover than those who take the experience in their stride, researchers in America said yesterday.

People who lower their stress levels before surgery with relaxation techniques, such as imagining they are lying on a beach in the sun sipping a cool drink, can increase the level of healing chemicals in their bodies, the researchers said. This can shorten the time they need to convalesce by several days.

The findings, presented by Professor Janice Kiecolt-Glaser from Ohio State College of Medicine, show that patients who are under psychological stress have higher levels of some hormones in their blood. These slow down the production of cytokines, chemicals involved in healing and reducing inflammation.

"Patients whose stress levels are reduced by relaxing techniques or being given information about their operation before surgery make quicker recoveries," Dr Kiecolt-Glaser said.

In previous studies conducted by the team, people who had small wounds inflicted on them took 24 per cent longer to recover, 46 days rather than 37 days, if they were under high stress.

In the latest research, Professor Kiecolt-Glaser and her colleagues gave 36 female volunteers blisters and then measured chemicals at the wound site up to 22 hours later. They found that stress made a difference even in the early stages of healing. Those women who reported greater stress had lower levels of cytokines.

In a second study, the researchers showed that getting people to relax helped the wound healing process by increasing their production of healing chemicals by a third. "A variety of relaxation techniques before surgery can really improve recovery," she said.