A study in the British Journal of Clinical Psychology found that 20% of ambulance workers are suffering from a psychological condition known as post traumatic stress disorder (PTSD).

The researchers also found that those ambulance workers who tried to forget about traumatic experiences were more likely to suffer from psychological problems.

Psychologists Sue Clohessy and Professor Anke Ehlers of Oxford University studied the experiences of 56 Oxfordshire Ambulance Service paramedics.

Symptoms of PSTD reported by those who took part in the study included:

• Intrusive memories of particular incidents
• Sleep problems
• Irritability
• Feelings of emotional detachment from colleagues

Cot death 'most traumatic'

Paramedics are exposed to traumatic scenes

Ambulance workers rated dealing with victims of cot-death as the most traumatic event with which they had to cope.

It was rated as more than twice as traumatic as handling dead bodies.

Almost nine out of 10 people who suffered from recurrent memories of an incident said they were related to the death of another person.

The most common event leading to post traumatic stress was a fatal road accident leading to the death of children, or of someone known to the paramedics.

Other incidents which were rated as traumatic were violent deaths, such as suicide victims who had shot themselves, and horrific burns accidents.

'Unwanted memories'

Paramedics also said that work pressures such as long shifts, waiting for the next 999 call and conflicts between work and home life also contributed to stress levels.

They said they tended to seek support from colleagues or loved ones, distance themselves mentally from the trauma or linger on the memories and wish they could change the outcome.

Experts warned that burying memories or indulging in "wishful thinking" could prolong the agony.

Professor Ehlers said: "Unfortunately for these workers, unwanted memories that pop into one's mind without apparent reason are among the normal reactions to traumatic events, and cannot be prevented by suppressing them."

Jon Richards, of public sector union Unison, said PTSD was a real problem in the service.

"There is a lot of early retirement and sickness in the service - basically if you get to 55 and are still working you deserve a medal," he said.