London, May 18 (IANS) Individuals suffering from chronic fatigue tend to be more anxious, distressed and are also more likely to suppress these emotions than people who do not have this condition, says a study.

In addition, when under stress, chronic fatigue syndrome patients show greater activation of the biological "fight or flight" mechanism, which may add to their fatigue, the study said.

"Patients with chronic fatigue syndrome often tell us that stress worsens their symptoms, but this study demonstrates a possible biological mechanism underlying this effect," said lead study author Katharine Rimes from King's College London.

The findings appeared in the journal Health Psychology.

The research that involved examining 160 people in Britain relied on self and observer reports, as well as physiological responses that were collected before, during or after the participants watched a distressing film clip.

Half of the participants had been diagnosed with chronic fatigue syndrome while the rest were healthy.

Half of each group were instructed to suppress their emotions and half were told to express their feelings as they wished. The researchers measured skin conductance in participants because this increases with greater sweating, which is a sign of activation of the body's sympathetic nervous system. This is often known as the biological fight or flight system used to cope with stress.

Regardless of the instruction they received, the chronic fatigue syndrome participants reported higher anxiety and sadness, and their skin responses indicated they were more distressed than the healthy control group, both before and after the film.

"These findings may help us understand why some chronic fatigue syndrome patients don't seek out social support at times of stress," Rimes stated.