By Melissa Maynarich, NEWS 9

OKLAHOMA CITY -- Mental health experts in the armed forces say it's not surprising that the suspect of the worst mass murder at a military post in U.S. history is an Army psychiatrist. They also have to deal with the traumatic stress of war.

There's a condition called "compassion fatigue." That's when a therapist is traumatized from hearing about the terrible things that happen in a warzone from their patients.

Major Nidal Malik Hasan treated soldiers at the Darnall Army Medical Center at Ft. Hood. In July, he was transferred there from the Walter Reed Medical Center where he studied and practiced psychiatry. The Oklahoma National Guard's Director of Psychological Health says mental health professionals can suffer from compassion fatigue.

"When we identify things in our own lives, or that we are being overloaded by the stress of providing care," said Major Brandon Wardell, with the Oklahoma National Guard. "One of the things, as our responsibility and obligation both legally and ethically, is to stay in consultation with other providers so that they can give us feedback about things their seeing about us."

In 2008, the American Psychiatric Association found that the war in Iraq has caused heightened stress, depression and sleeplessness among military personnel and their families.

As a result, it's reported that mental health professionals are seeing extremely high levels of post traumatic stress disorder and substance abuse among soldiers who return to the U.S. - a level that may have affected Hasan.

"I think everybody has a limit on their stress," said Wardell. "I think one of the things, yes I mean, sure, anybody has that potential, I assume."

Hasan was set to deploy to Afghanistan with an Army Reserve unit that provides "behavioral health" counseling for troops. To deal with the anxiety surrounding deployment, the military has resources in place to prepare service members for the trip overseas.

"This was an isolated incident with that individual, it's not indicative the things that we go through," said Wardell. "We've got a lot of programs in place that help service members and their families."

It's not clear whether the psychiatrist who opened fire at Ft. Hood suffered from compassion fatigue, but professionals say it's a possibility.

An official at Walter Reed Medical Center says Hasan had some difficulties that required counseling and extra supervision during his time there.