That could be part of the reason Maj. Nidal Malik Hasan opened fire inside his military base in Fort Hood, Texas Thursday, killing a dozen military members.

It's possible as the military psychiatrist neared his own deployment, the stories his fellow comrades were sharing with him hit a little too close to home.

Clinical Psychologist Dr. David Clayman said if Hasan wasn't finding ways to vent, the stories of trauma and sadness may have been too much for him to bear.

"The burden of confidentiality of coming up with answers and helping people through things, we take it home, not on an every day basis, but the cumulative total on us is significant. we are just like other people. we hear the stories and we can only be dispassionate for so long," said Clayman.

Clayman said military personnel who don't deal with their stress have greater physical and psychological problems.