If you are infected by an influenza or cold virus, the chance that you’ll actually develop symptoms is forty percent less if you are happy, energetic and in harmony than if you don’t have these positive feelings. A positive mood and attitude has a positive effect on your immune system, say psychologists at Carnegie Mellon University.
Research that Sheldon Cohen published in 2006 in Psychosomatic Medicine resembles that done in an earlier, similar study in 2003. For this, the researchers infected about 350 subjects with a cold virus and then looked at who actually developed symptoms. [Psychosom Med. 2003 Jul-Aug;65(4):652-7.] The researchers discovered that subjects who felt energetic, happy and calm – those who had a positive emotional style – developed colds less often.
In 2006 the researchers more or less repeated the same experiment with just under 200 women aged between 21 and 55. Two weeks before the subjects were given nose drops with either rhinovirus RV39 or the influenza virus A/Texas/36/91, they had to answer questions on their state of mind. After the subjects had been infected they had to stay a week in quarantine, and the researchers watched to see which of them became ill.
The 33.3 percent of the women with the least positive emotional style were more often ill than the 33.3 percent of the women with the strongest positive emotional style. A negative emotional style – used to describe the subjects who were unhappy, angry or stressed – did not increase the chance of developing symptoms. Apparently positive feelings improve natural resistance, but not the other way round – negative feelings don’t have a negative effect.
The researchers then also looked at whether the state of mind of the subjects that had become ill meant they were less affected by the infection. In this case the positive-minded subjects suffered less from the virus that had made them ill. But the subjects with negative feelings were even worse off: they were more affected by their illness than the subjects with fewer negative feelings.
“We found that the tendency to express positive emotions was associated with greater resistance to developing a cold”, the researchers conclude. “We also found that positive emotional style was associated with fewer self-reported symptoms after removing the possible contributions of objective illness.”
Psychosom Med. 2006 Nov-Dec;68(6):809-15.