Re-reading the books now after having watched season 2.
Milk of the Poppy is pretty straightforward. But what is Dreamwine supposed to be? The Westeros version of NyQuil? What is the active ingredient (other than alcohol)?
Some Valium equivalent, I assumed.
Ye Tyrian Purple Drank
“flavoured with strange spices”… wormwood? It makes me think either: some weird, narcotic additive, or a wine with a high alcohol content that makes you full and sleepy. Like barleywine, except that’s a beer. Barleybrandy?
Or a dragon did it.
I’d imagine, never having read the book and seen only a few episodes, that it’d be wine laced with ergot or some other hallucinogenic fungus.
Or hell, why assume it’s grape juice at all? Maybe it’s just a euphemistic expression for reindeer piss.
I think something to keep in mind, is that even beyond the actual magic and fantastical elements to the shoe (dragons, White Walkers,) there is still some things that are still mundane, but don’t exist in our word.
Dreamwine could be an example. There could easily be a plant in Westeros and/or Essos that has mild hallucinogenic and/or sedative properties with no “real world” equivalent. Maybe there’s a flower out there who’s leaves naturally make Ambien, or something.
But yeah, I always took it to be something that both helped you sleep, and could give you weird/vivid dreams. Otherwise it would probably just be called Sleepwine.
I assumed it was laudanum.
Since they talk about poppy in other contexts, I don’t think dreamwine is laudanum (which is poppy).
I’m not an expert on psychotropic plants, but the descriptions of the effects, particularly with Tyrion, struck me as similar to belladonna. But probably the writer didn’t have any particular real life plant in mind at all; writers do that.
You know, it could be. Certain shamans effectively processed a particular psychedelic mushroom (fly agaric, I believe) that would otherwise be extremely unpleasant through reindeer–let them eat the 'shrooms, collect the reindeer pee, and there you go.
So hey, who knows! 
Aha! You’re right. Just saw this in Storm of Swords:
Looks like it’s wine laced (not too heavily) with opium.
Thanks, all.
Isn’t Dreamwine the same thing that they gave to Robyn Arryn and Bran while they struggle through bad dreams?
I’m pretty sure they mix milk of the poppy into the dreamwine for Tyrion to lessen the pain. If it is the same drink that the maesters serve to little Robby Arryn, then it is not milk of the poppy directly, it’s something different that the sickly, or the medicated can’t use too often, or in large doses. In small doses, it induces sleep, in large doses, or freuqent doses, it kills people.