One in five members of the armed forces experience psychological distress while on deployment, according to research by King’s College London.
They studied 611 personnel based at eight locations in Iraq at the beginning of this year.
They found 20.5 per cent showed signs of psychological distress and 3.4 per cent had probable post-traumatic stress disorder.
They found personnel who were young, female, in the army, and of junior rank were most at risk.
Those who reported sick for any reason were also more likely to have symptoms of psychological distress.
The authors said: “Raising awareness among staff of the link between personnel reporting sick and having poorer mental health may help identify those most in need of psychological help.”