I think he was probably using LSD but that still doesn't explain how he wound up in a hospital without anyone in the staff knowing how he got there or whats wrong with him, even he was in shock or tripping balls ER staff would know what to do thus it would be that big a deal and definatly would not stump a doctor. IMO I believe he was using LSD in an attempt to find some sort of enlightenment or greater understanding of the world, then out of nowhere these beings abduct him and give him the enlightenment and answers he was trying to find with his "need to know potion" and send him back. But ironically the drugs he was using in an attempt to gain this knowledge are the very thing that kept him from comprehending/remembering what they told him.

From this day forward I will ALWAYS carry a pen!