A single dose of psilocybin, the active ingredient in the infamous psychedelic mushrooms indigenous to Mexico, triggered long-lasting mystical experiences in several dozen middle-aged volunteers enrolled in an unusual study at Johns Hopkins University.

Roland Griffiths and his colleagues brought 36 people into the laboratory for an eight-hour session during which they experienced their first psychedelic high. Two thirds of them said that the trip was among the most profound spiritual events in their life, Griffiths reports. A third rated it as their number-one awakening, and their family and co-workers said they seemed happier in the months after the experiment, according to a follow-up study just concluded.

Griffiths says he embarked on the controversial experiment because psychedelics constitute “a whole class of drugs we know very little about.” Research came to a halt after investigators such as Harvard University’s Timothy Leary in the heady 1960s swallowed their own research pills in the name of science. Griffiths says the findings suggest these drugs, or safer versions of them, could be used to treat addictions, because many recovery programs are based on models of spirituality. The drugs could also help overcome depression.

Johns Hopkins recruited people with no history of mental illness or psychedelic drug use. Each volunteer received eight hours of preparation. Their trip took place in a living room setting with two monitors present. Half received the real drug, and the others were given an amphetamine or a placebo. According to Griffiths, the subjects who received psilocybin said they “had a sense of pure awareness. They described feeling infinite love, tenderness and peace. Everything was experienced in the present; the past and future had no meaning.” Nevertheless, a third of these volunteers felt significant fears afterward, and some experienced paranoia. “These drugs should not be used recreationally,” Griffiths notes.