The stress caused by a 30-minute row with a spouse is enough to slow wound healing by a day, US researchers say.
Scientists say cutting stress could shorten hospital stays
The Ohio State University team focused on 42 married couples and found wounds on hostile couples healed at 60% of the healing rate for non-hostile couples.
The team told the journal Archives of General Psychiatry the findings showed hospitals should try to minimise stress for patients ahead of surgery.
This could lead to shorter hospital stays and save money, they added.
The researchers focused on a group of 42 married couples who had been together an average of at least 12 years.
Each couple was admitted into the University's General Clinical Research Center for two, 24-hour-long visits, separated by a two-month interval.
During each visit, both the husband and wife were fitted with a small suction device which created eight tiny uniform blisters on their arms.
The skin was removed from each blister and another device placed directly over each small wound, forming a protective bubble, from which researchers could extract fluids that normally fill such blisters.
The husbands and wives also completed questionnaires intended to gauge their level of stress at the beginning of the experiment.
Each person was also fitted with a catheter through which blood could be drawn for later analysis.
During the first visit, each spouse was asked to talk for several minutes about some characteristic or behaviour which he or she would like to change. This was a supportive, positive discussion.
But during the second visit, they were asked to talk about an area of disagreement which provoked strong feelings.
Analysis showed wounds took a day longer to heal after the arguments than they did after the initial supportive discussion.
Wounds on the hostile couples healed at only 60% of the rate of couples considered to have low levels of hostility.
Blood samples from those highly hostile couples showed differences as well.
Levels of interleukin-6 (IL-6), a key immune system chemical that controls wound healing, were also particularly elevated in the hostile couples.
High IL-6 levels are linked to long-term inflammation, which in turn is implicated in a range of age-related illnesses, including cardiovascular disease and arthritis.
Researcher Professor Jan Kiecolt-Glaser said: "In our past wound-healing experiments, we looked at more severe stressful events.
"This was just a marital discussion that lasted only a half-hour.
"The fact that even this can bump the healing back an entire day for minor wounds says that wound-healing is a really sensitive process."
Professor Steve Bloom, an expert in stress at Imperial College London, said "These findings are interesting, and illustrate yet again the control that the mind has over the body."
However, Professor Bloom said the skin was particularly sensitive to emotional states - for instance increased blood flow quickly results in blushing when somebody is embarrassed.
He said it was "speculative" to draw conclusions about wound healing, for instance, of the major internal organs from research focused on the skin.
He also said that slowing down the immune response could sometimes be positive.
"Cross infection rates shot up when people started living in cities," he said.
"More than 50% of people died in the first year of life. So those that survived developed hyperactive immune systems to help them combat infection.
"However, this has left us prey to autoimmune diseases such as eczema and asthma, so if stress slows down the immune response a bit that may not be such a bad thing."