After watching the promo i got to the next conclusion. Sam&Dean are trapped in the mental institution by someone who wants them to think that their whole life is an lie(that there is no Azazel,no monsters,no Lucifer and angels)!Watch the trailer and tell me what you think!

i alreadt posted this spoiler! I'll just go deleat mine doesnt need to be on here twice!

[“Sam, Interrupted,” airing January 14], the boys are contacted by a hunter who had worked a case that was so traumatic that he went crazy. He’s been voluntarily living in an insane asylum and something not right is happening there, and he calls the boys. So Sam and Dean check themselves in. The challenge of an episode like this is that it’s well-trodden territory in horror movies and television shows, so we made sure we had a different take. You don’t have to be crazy to be a hunter, but it helps. That’s what Sam and Dean explore. We’re also doing our twist on a zombie story. It’s different from the Croatoan virus zombies. These are post-modern with lots of personality-taken from Sera Gamble interview

Ok...sorryXD

I think that you are wrong. I also think that the boys once there will be medicated , to cause them to hallucinate.