I dont look at cannabis as a strong hallucinogen but to say that it is, is to call nicotine(I dislike) an equal to that of cyanide via cranking up the dose to unusual levels. However, due to varying sensitivities in people, I would imagine you can find individuals that trip from THC. Most traditional hallucinogens are active via seritonin receptors if im not mistaken, cannabis is via cannaboid receptors, a different section of the brain all together
Dreams are just self-induced DMT(more intense than LSD) trips. So force the state of mind or not, something similar happens on a normal routine in the brain.
Dreaming seems to be a needed function to allow the brain to cope. (Nightmares are bad trips I guess.) I've always looked at it like digestion for the brain, flushing, reorganizing, or maybe like scan disk for a computer hard disk checking and fixing.
I think hallucinations are something your brain, and you, can take something from. Still much depends on frame of mind, setting and substance. Forcing your mind into various states of mind, or learning how to do it at will is beneficial, under the same idea, that while in that state of mind you are able to bring some of the feeling and ideas back into a somber, sober, self.
Cannabis hinders productivity or drive(I think mainly to the short term memory loss), but it does help with mood and anxiety. I personally dislike alcohol and its use, I believe it to be destructive more so than cannabis in terms of cost of human life, but more specifically the cost to other humans that did not choose to imbibe.
But I am no PhD, all of the above is simply from experience so far and a bit of research I've done out of curiosity.
