I'm no psychedelic prude. I reported on, and applauded, the resurgence of research into psychedelics in my 2003 book Rational Mysticism. I participated in a peyote ceremony of the Native American Church, and I advocated legalization of psychedelics for therapeutic purposes. But the enthusiasm with which some journalists are now touting psychedelics makes me a bit uneasy.

As William James warned, mystical visions can be "melancholic" and "diabolic" as well as consoling.

Take for example "The Trip Treatment," in the February 9 New Yorker. Michael Pollan provides an in-depth report on research at New York University, Johns Hopkins, UCLA and other major institutions into the therapeutic benefits of psychedelics.

Pollan includes obligatory reminders about the excesses of the Sixties, when Timothy Leary morphed from Harvard psychologist into LSD evangelist and urged young people to "Turn on, tune in, drop out." Pollan quotes Nora Volkow, director of the National Institute on Drug Abuse, cautioning that "drugs of abuse outside a research setting can produce serious harms."

But Pollan states that researchers at NYU and Johns Hopkins, who have overseen almost 500 sessions of psilocybin, the primary active ingredient of hallucinogenic mushrooms, have reported "no serious negative effects." This finding "is perhaps less surprising than it sounds," Pollan adds, "since volunteers are self-selected, carefully screened and prepared for the experience, and then guided through it by therapists well trained to manage the episodes of fear and anxiety that many volunteers do report."

Pollan argues that psychedelics' clinical benefits are not merely chemical--like those of, say, Prozac--but rather psychological and even spiritual. Psychedelics often induce mystical experiences, as defined by psychologist William James in his classic, century-old work The Varieties of Religious Experience.

Such experiences include "feelings of unity, sacredness, ineffability, peace and joy," Pollan says, as well as the conviction that you have discovered "an objective truth about reality." Many mystics encounter a loving divinity and lose their fear of death.

Unfortunately, not all mystical experiences yield such consoling revelations. William James emphasized that some mystics perceive absolute reality as terrifyingly alien and uncaring. James called these visions “melancholic” or “diabolical.”

James himself was tormented throughout his adult life by panic attacks, which convinced him that ultimate reality is meaningless. He desperately sought positive mystical visions by eating peyote and inhaling nitrous oxide--in vain.

Taking psychedelics in a supervised research setting will not necessarily eliminate the risk of a bad trip. That lesson emerged from a study carried out in the early 1990s by psychiatrist Rick Strassman, who obtained permission from federal authorities to inject the psychedelic dimethyltryptamine, DMT, into human volunteers.

From 1990 to 1995, Strassman supervised more than 400 DMT sessions involving 60 subjects at the University of New Mexico. Many subjects reported that they dissolved blissfully into a radiant light or sensed the presence of a powerful, god-like being.

On the other hand, 25 subjects underwent what Strassman called “adverse effects,” including terrifying hallucinations of “aliens” that took the shape of robots, insects or reptiles. Some subjects remained convinced that these aliens were real in spite of Strassman’s efforts to convince them otherwise. In part out of concern about these adverse effects, Strassman discontinued his research, which he describes in his 2000 book DMT: The Spirit Molecule. (For more on Strassman’s study, see this link.)

Concerns about psychedelics were also voiced by Albert Hofmann, the Swiss chemist whose research helped catalyze the Psychedelic Sixties. Hofmann discovered the properties of LSD in 1943, and a decade later he synthesized psilocybin.

When I interviewed him in 1999, Hofmann acknowledged that if used improperly, LSD "can hurt you, it can disturb you, it can make you crazy." But Hofmann believed that scientists and psychiatrists should be allowed to investigate LSD’s effects and prescribe it in a safe, controlled fashion. "I don’t want to promote absolute freedom," Hofmann said, "but the medical professions should have access to it."

Used with respect, he said, LSD has enormous potential as a tool for investigating human consciousness and as an adjunct for psychotherapy. Psychedelics can also stimulate the "inborn faculty of visionary experience" that we all possess as children but lose as we mature. Hofmann hoped that in the future people would be able to take psychedelic drugs in "meditation centers" to awaken their religious awe.

Yet in his 1980 memoir LSD: My Problem Child, Hofmann confessed that he sometimes had misgivings about having brought LSD into the world and helping to popularize psilocybin. He compared his discoveries with that of nuclear fission; just as fission threatens our fundamental physical integrity, so do psychedelics "attack the spiritual center of the personality, the self." Psychedelics, he feared, might "represent a forbidden transgression of limits."

He worried about psychedelics’ metaphysical implications. The fact that minute amounts of a chemical such as LSD can have such profound effects on our perceptions, thoughts and beliefs suggests that free will, which supposedly gives us the power to shape our destiny, might be an illusion; moreover, our deepest spiritual convictions may be nothing more than fluctuations in brain chemistry. To emphasize this point, Hofmann quoted from an essay that stated: "God is a substance, a drug!"

I've had good trips, that left me feeling profoundly grateful to be alive, and bad ones, including one that met James's definition of a "diabolical" experience. Psychedelic therapists can no doubt minimize the risks of adverse reactions by choosing drugs and dosages carefully, screening subjects and closely supervising their sessions. But I doubt bad trips can ever be entirely eliminated. And maybe they shouldn't be, because our visions of hell may have as much to teach us as our visions of heaven. We should keep this possibility in mind as the psychedelic revival rolls onward.

Further Reading: This column includes material from my previous writings about psychedelics, including a few of the columns below:

"Does Psychedelic Therapy Exploit the Placebo Effect?"

DMT is in your head, but it may be too weird for the psychedelic renaissance.”

"What Should We Do With Our Visions of Heaven—and Hell?"

"My Ayahuasca Trip."

Tripping in LSD’s Birthplace: A Story for ‘Bicycle Day’

Doubts about psychedelics from Albert Hofmann, LSD’s discoverer

"My Lunch with Psychedelic Chemist Sasha Shulgin."

Was Psychedelic Guru Terence McKenna Goofing About 2012 Prophecy?

*This headline replaces--and is much, much better than--my original one: "As Psychedelic Revival Continues, Don't Forget Bad Trips."

Image: Wikimedia Commons.