By Fiona Macrae
PUBLISHED: 14:01 EST, 2 April 2012 | UPDATED: 14:01 EST, 2 April 2012
Stressed out? Best look away now because reading on could make you ill.
Scientists have shown how long-term stress plays havoc with the immune system, raising the odds of catching a cold.
The same process could explain the role of traumatic events from divorce or death of a loved one to staring a new job in raising the odds of ills from heart disease to depression.
The research comes from U.S. scientists who looked at whether people who had been under a lot of pressure in their day-to-day lives were more likely to catch a cold than those who were more relaxed.
Some 176 men and women were quizzed about any painful or difficult times they had been through in the previous 12 months.
They also underwent tests to examine how well their immune system responded to dampening effects of the stress hormone cortisol.
They then had drops of the common cold virus dripped into their nose and were monitored to check if they caught the germ.
Those who had been under stress were twice as likely to develop a cold and tests showed their immune systems to be less sensitive to cortisol.
This allowed a part of the immune reaction called the inflammatory response to grow, leading to the symptoms of the cold, the journal Proceedings of the National Academy of Sciences reports.
A second experiment confirmed that the inflammatory response feeds off stress.
Inflammation, which can show itself as redness, itchiness, swelling and pain, occurs when the immune system spots an infection and is a vital first step in fending off disease.
However, when it persists, it not only raises the risk of colds but many other illnesses.
Researcher Professor Sheldon Cohen, of Carnegie Mellon University in Pennsylvania, said: ‘The immune system’s ability to regulate inflammation predicts who will develop a cold, but more importantly it provides an explanation of how stress can promote disease.
‘When under stress, cells of the immune system are unable to respond to hormonal control, and consequently, produce levels of inflammation that promote disease.
‘Because inflammation plays a role in many diseases such as cardiovascular, asthma and autoimmune disorders, this model suggests why stress impacts them as well.
‘Knowing this is important for identifying which diseases may be influenced by stress and for preventing disease in chronically stressed people.’
There are also many other ways that stress can make us ill.
For instance, researchers at the London School of Economics have warned that a growing reliance on fat and salt-laden fast food and time-saving technology, coupled with long working hours, is sending blood pressure soaring.
One third of British adults already suffer from the condition which doubles the risk of dying from heart attack or stroke.
Research has also linked stress, anxiety and low self-esteem in pregnant women with an increased risk of stillbirth and with stunting a child’s intelligence.
Children from stressed pregnancies are also more likely to be hyperactive, have emotional problems and not do as they are told as well as suffering from stress themselves.