Men who experienced high levels of psychological stress were found to be less able to withstand physical pain.
In a study of 29 men, the research team - led by Prof. Ruth Defrin of the Department of Physical Therapy at Tel Aviv University in Israel - found that psychological stress significantly increases pain intensity while reducing the ability to cope with it.
The participants were required to take part in the Montreal Imaging Stress Task (MIST), a computer-based algorithm designed to induce psychological stress.
The researchers describe MIST as a "psychological trick." It involves participants answering a number of test questions. Prior to responding to the questions, they are told that the average score a person achieves is 80-90%. However, participants are unable to score above 45%, no matter how hard they try, causing them to become psychologically stressed.
Before and after the MIST test, the participants underwent a series of experiments that assessed their threshold to heat pain and their ability to cope with this type of pain. For example, in one experiment, the participants were exposed to a gradually increasing heat stimulus and were asked to indicate at what point they felt pain.
The researchers divided the participants into groups based on their stress levels as measured by the MIST test, before assessing how stress affected their ability to withstand pain.
Psychological stress 'decreased pain modulation in a very dramatic way'
The researchers found that the men who experienced higher levels of psychological stress had a much lower ability to withstand pain, compared with men who had lower stress levels.
"The higher the perceived stress, the more dysfunctional the pain modulation capabilities became. In other words, the type of stress and magnitude of its appraisal determine its interaction with the pain system," explains Prof. Defrin.
The researchers say their findings were surprising. People who are injured during sports, for example, are reported to have better pain modulation, so they expected to see similar findings in their study.
"But we were surprised to find quite the opposite," says Prof. Defrin. "While there was no visible effect of acute stress on the subject's pain threshold or tolerance, pain modulation decreased in a very dramatic way."
Based on their findings, the researchers advise that we reduce our exposure to stress wherever possible. Prof. Defrin adds:
"Modern life exposes individuals to many, recurrent stressful situations. While there is no way to predict the type of stress we will feel under different circumstances, it is advisable to do everything in our power - adopt relaxation and stress reduction techniques as well as therapy - to reduce the amount of stress in our lives."
Last week, a report from the American Psychological Association revealed that while overall rates of stress are falling in the US, money is still the main cause of stress in Americans.