Wormwood is really interesting, and it's one of my most reliable dream aids. The main advantage with this herb, for me, is that it generates inordinately peaceful sleep (MUCH better than any pharmaceutical sleep aid) and very vivid dreams (though not necessarily lucid ones). Perfect combination really, and an unusual one since most dream enhancers tend to prevent good sleep.

The downsides are two-fold: on the one hand it is truly disgustingly bitter, and on the other it is supposed to be somewhat taxing on the kidneys. The first of these issues I have (more or less) overcome by making a tincture from it, and I take 20-60 drops of it (this is still a bitter experience, but not comparable to drinking a water-based infusion of it). The second issue is simply handled by not using it often (for me probably once every other week).

I have never experienced adverse effects of wormwood.

What I have found interesting is that it works much better for dreaming than mugwort does, even though mugwort has a long history behind it of being used as a dream aid.