I've read several experiments on the internet according to which it is possible to reach a psychedelic state without taking any psychedelic drugs like DMT, LSD and other tryptamine derivatives.
It may sound stupid but I was thinking that the brain produces some minimal amounts of a psychedelic drug. Maybe it is a tryptamine derivative (from the metabolism of the amino acid tryptophan, or from melatonin). I think that there is an undiscovered biological pathway for endogenous psychedelics (I can imagine DMT or 5-MeO-DMT).
What do you think about this? How can the brain go into a psychedelic state without taking any psychedelic drugs?