The UK armed forces have suggested deployment levels called the harmony guidelines due to the fact that prolonged deployment in the armed forces could lead to mental health problems. The guidelines are reflecting the need to balance rest and recuperation with deployment.

Professor Roberto Rona and associates at King’s College London decided to test whether deployments above the guidelines mentioned, calculated as 13 months or more in a three year period, would have adverse effects on psychological health of the soldiers.

The study included 5,547 regular military personnel, the number and duration of their deployments in the last three years and assessed mental health and alcohol use. They also tracked their intensions to stay in the military and problems at home during and after deployment. The analyses were adjusted for factors such as age, gender, rank, marital status and Service as well as for role in theatre (combat or support), type of deployment (war or peace enforcement operations), and time spent in a forward area in close contact with the enemy.

The study results showed that those people who were deployed for 13 months or more over a three year period, especially those who were in direct combat, were more likely to have symptoms of post traumatic stress disorder and experience problems at home during and after deployment. Alcohol usage and problems related to it also increased with longer deployment.

No association was found between duration of deployment and intention to stay in the military nor between number of deployments and psychological symptoms.

However, longer than expected periods of deployment and uncertain date of returning home have been linked to post traumatic stress disorder not just in British soldiers but in American ones as well.

In order to reduce the risk of post traumatic stress disorder, armed forces will have to make a clear and explicit policy on the duration of each deployment.