There is a long tradition in psychology of using psychoactive substances to explore altered states of consciousness. Back in the 19th century, William James experimented with amyl nitrate, chloral hydrate and peyote to learn about mystical experiences while Sigmund Freud experimented with cocaine (and became a frequent recreational user as well).
Despite the backlash against psychoactive drugs in the early years of the 20th century, new possibilities arose with advances in biochemistry. When lysergic acid diethylamide (LSD) was first synthesized in 1938 by the Swiss chemist Albert Hoffman, he actually had no idea what he had discovered. The compound was developed as part of a research program searching for ergot alkaloid derivatives that might be useful in the treatment of migraine headaches. Aside from the "restlessness" that was observed in laboratory animals that were given LSD, no particular value was found in it and Hoffman shelved his discovery for five years. It was in 1943 when he accidentally spilled some of the LSD on his skin that Hoffman slipped into a stupor and, in a dreamlike state, experienced "fantastic pictures, extraordinary shapes with intense, kaleidoscopic play of colors". That was the beginning of his research into the effects of LSD using himself as a guinea pig. Hoffman's graphic descriptions of visual illusions with bright, intense colours, multiple images of geometric patterns, distortions of body image and subsequent feelings of heightened sensitivity inspired his employers at Sandoz laboratories to perform experiments on other test subjects.
It was Walter Stoll, a psychiatrist at a psychiatric clinic in Zurich, who first began examining the effects of LSD in psychiatric patients and control volunteers. The publication of Stoll's research in 1947 electrified the psychiatric community and Sandoz began marketing LSD as a valuable psychiatric drug under the trade name "Delysid". Not only did Sandoz advertise Delysid as a potential panacea for most mental illnesses (including criminal behaviour and sexual perversions), they also recommended that psychiatrists take it themselves to "gain an understanding of the subjective experiences of the schizophrenic". The key assumption that underlay Sandoz's marketing strategy revolved around what would be known as the "model psychosis" hypothesis. The minute amounts of LSD that led to psychotic features developing in otherwise normal subjects reinforced the idea that schizophrenia and related psychiatric conditions were purely biochemical in nature. Was it not likely that mental illness was due to the human body generating LSD-like substances under conditions of extreme stress? Could research into chemical agents that interfered with the "psychosis-simulating" effects of LSD lead to new biochemical treatments for mental illness? The serotonin (5-HT) hypothesis of schizophrenia was first proposed during this period based on the observation that hallucinogenics such as LSD and mescaline functioned by acting on 5-HT receptors in the human brain. While the actual mechanisms involved appears to be far more complex than initially thought, it seemed only natural for medical researchers of the period to believe that LSD represented a powerful new tool in treating mental illness.
Delysid/LSD first became commercially available in 1947 and demand by researchers led to its wide availability around the world in a matter of months. Despite being marketed to medical doctors, early LSD advocates including Aldous Huxley and Alfred Hubbard (a.k.a. "Captain Trips") ensured that LSD would be seen as far more than a medical tool. Huxley wrote The Doors of Perception (1954) and Heaven and Hell (1955) based on his experiences with LSD and mescaline and these books quickly became classics. While no one could have ever foreseen the role that LSD would play in the counterculture movements of the 1960s, the recreational possibilities seemed clear enough.
From 1950 to 1965, research into LSD and related hallucinogenics generated over 1000 scientific papers and books and was the subject of at least six international conferences. Thousands of patients received LSD as a treatment for everything from schizophrenia to alcoholism.