Our senses and our memory give us the impression that our day to day world is normal. A combination of mind-altering substances and/or questioning your most fundamental belief systems, those fed in the early years by parents, media, care-givers, church, social culture in school, work culture, can allow you to realize on many levels just how unique this life is. These meetings with other entities, etc. are still very human brain oriented, and a drug could activate it in the necessary pattern.
Dreams are somewhat an interest of mine, becuase plot and interaction-wise, they are the most fucked up experiences I have. And they're manufactured in my head. What makes them boring is the amnesia and anesthesia the brain creates for us during the dreaming process.