US researchers set out to test the chemicals produced when 36 female volunteers were given minor blisters.
They found that those women who were under the greatest stress produced lower levels of two key chemicals called cytokines.
These chemicals help cause inflammation, which is an important part of the healing process.
Eight small blisters were produced on each of the volunteers who took part in the study by using a sunction pump.
The researchers measured the chemicals produced by the body for 22 hours after injury by testing changes to a mixture of blood serum and salt solution added to the wound site.
In a second study, the researchers also showed that getting people to relax helped the wound healing process.
This was done using recognised techniques such as imagining pleasant scenes or focusing on the blood flow in the arm.
Tests showed a greater migration of immune system cells to the blister sites of the relaxed participants.
When a wound occurs, immune system cells converge on the site of the injury and start the healing process.
Increased cell migration signifies improved and quicker healing.
Counselling may work
The research was carried out by Professor Janice Kiecolt-Glaser, of Ohio State College of Medicine. She reported her findings to the annual conference of the British Psychological Society on Thursday.
She said her findings suggested that patients awaiting surgery should be given help to reduce their anxiety levels.
This could be done through counselling, or by using anti-anxiety drugs.
Professor Kiecolt-Glaser told BBC News Online: "This may help to explain why there is evidence from a number of psychological studies suggesting that people who are more stressed or anxious before surgery may require a longer time to recover and may experience more complications.
"The medical system does not pay attention to psychological state even though there is data to show it has an imorportant and significant impact on recovery."
Earlier studies have suggested a link between healing and stress.
In one, volunteers who had a piece of tissue punched from their skin took nine days longer to heal when stressed.
Another group took 40% longer to recover from a wound inside the mouth when they were about to take an exam.
Doctors had also noticed that patients helped to relax before an operation recovered more quickly, often being kept in hospital one or two fewer days.