In the Vietnam War, Bob Walker had been a helicopter mechanic, and he’d watched as his best friend was decapitated by an incoming helicopter’s propeller blade. People with PTSD can be highly irritable and suffer from insomnia, nightmares, and the inability to sustain deep relationships. “Over the years, I tried everything from prescription drugs to biofeedback,” says Walker. Bob Walker has suffered from PTSD for over 30 years.