Brian Keenan is all too familiar with some of what they are experiencing. He spent four years as a hostage in Lebanon. "I reckon I was in the dark about seven or eight months. I can't be sure; it's very hard to tell the time.
"The nothingness, that was extremely hard. Because the question in your head is how am I going to get through the next 10 minutes? Or months later, how am I going to get through the next day? Is there enough left in my head?"
"I remember one occasion waking up and having to squeeze my face and my chest and thinking to myself 'Am I still alive?'"
People are actually volunteering for this, and it's all gonna be filmed for BBC Horizon. It just scares the crap outta me.