The behavior of someone on LSD and a small child are very similar. I believe that there is a naturally occurring "LSD like" chemical that we are all born with that wears off over a period of 16 to 25 years. During this time we call "maturing," it should be expected that the child will make really stupid and thoughtless mistakes. - Psychotic Kids
There actually is a substance in the brains of most people similar to LSD.
It's called DMT or dimethyltryptamine. It is similar in structure to serotonin.
"DMT is created in small amounts by the human body during normal metabolism by the enzyme Tryptamine-N-methyltransferase."
But the body quickly metabolizes it before we are aware of any effects.
However, perhaps in children, they may react to the brief moment when their brains are affected by DMT.
Hence the play of children where they talk to imaginary friends might be part of the normal "delusions" and "hallucinations" of childhood.
Thus mental illness and drug highs may be due to psychological immaturity, a side-effect of that inherent brief "psychosis" called childhood