Hallucinogens are a group of drugs that affect the central nervous system.
Some hallucinogens that grow naturally include the following. Varieties of morning glory seeds and mushrooms. Some hallucinogens that are produced chemically include the following. Hallucinogens, both naturally occurring and manmade, can alter perceptions of time and space, create visions, intensify color and heighten the user's mental awareness. These reactions are the result of changes in the brain's ability to transmit nerve impulses from one nerve cell to another.