The drug that causes dreams is now known to be a tryptamine derivative, most likely DMT.
Research into DMT causing dreams has been made hard by anti drug laws and govenment pressure.
Quote from University of California, Berkeley, http://sulcus.berkeley.edu/mcb/165_00...
"The striking similarity of entheogenic experiences to dream experiences tempts us to seek answers as to whether the benefits of dreaming are potentially linked to the benefits of entheogens. The molecular action of visions produced by dreaming is quite possibly very similar to visions produced by entheogenic drugs. Carefully designed research could lend great insight into the mystery of dreaming, the potential therapeutic value of entheogens, and the potential for neurochemical advances."
they conclude with
"Entheogenic drugs and dreams alike have a special place in the evolution of humankind and its value systems. Profound musical inspirations and scientific discoveries of the past century have even been inspired by them. Our ancestors religious views and values were influenced by their faith in visions communicated by entheogenic drugs and dreams. In an age of environmental destruction and moral erosion, the knowledge afforded by dream and entheogen induced visions could not be more valuable. Let us hope that our culture is fortunate enough to open our minds and build on the mysteries our ancestors have explored for ages."
School of Pharmacy, University of California
http://www.ncbi.nlm.nih.gov/sites/ent...
"The visions of dream sleep are suggested to occur through a dream mechanism which implicates tryptamine derivatives as endogenous paychedelics. The hallucinations that occur in some schizophrenic syndromes are also proposed to occur through a similar, though desynchronized, mechanism. These compounds occur in the human pineal gland and are regarded as neurotransmitters or neuroregulators. A protocol for experimental verification is suggested."
http://en.wikipedia.org/wiki/Dimethyl...
"Dr. Rick Strassman, while conducting DMT research in the 1990s at the University of New Mexico, advanced the theory that a massive release of DMT from the pineal gland prior to death or near death was the cause of the near death experience (NDE) phenomenon. Several of his test subjects reported NDE-like audio or visual hallucinations. His explanation for this was the possible lack of panic involved in the clinical setting and possible dosage differences between those administered and those encountered in actual NDE cases.
From a researcher's perspective, perhaps best known is Rick Strassman's DMT: The Spirit Molecule (ISBN 0-89281-927-8)"
