Concerning narcolepsy, I agree with @Mogaoscar. I doubt that the authors of Key have made any detailed investigations concerning the medical background of the disorders they are using. Heck, they are definitely taking trauma too lightly in LB. The characters are cured too easily, too quickly. But that’s how things work in the Little Busters universe. Their aim has never been to provide a detailed and scientifically accurate insight for trauma and the problems that come with it.
My take on narcolepsy is the following: It’s 100% self-induced. When Riki had decided to not to be born in order to never lose anyone precious again, this is how his subconsciousness had manifested it. Every time he is about to lose someone, he faints. It’s a self-defence mechanism to knock him out before the shock of “loss” hits him with its full brunt. He temporarily disconnects himself from the world.
What I mean is: It’s all in his head. His organs, tissue, blood flow, etc. had not been actually been tampered with. The brain controlls it all. Therefore, the moment he made the decision to face his fears and to “be born”, the now obsolete mechanism got removed.
The thing is, just because Kyousuke has made some things happen doesn’t mean he made everything happen.
I’m so sure of this due to what I think how the dream world works. Attributing everything to Kyousuke means denying some of the properties of the dream world.
Based on what Midori said in one of its ends, it’s a world that fulfills wishes. The wishes of those that create it. It’s a function with a direct connection to its properties. The girls all had regrets they wanted to deal with before dying. That enabled them to create the world in the first place, along with the LB boys. Therefore, it makes things happen so that those regrets can be resolved. Therefore, events that are directly connected to the heroine’s regrets… happen. Events that contain information Kyousuke couldn’t possibly have known unless he had somehow read through all the heroine’s memories. Stuff like what happened to the heroines, how the people and places involved looked like, etc.
I have probably explained that in detail somewhere on this forum, so I hope this suffices for now.