LSD may have opened and expanded the minds of the free thinkers in the ’60s, but the United States government quickly closed those minds after temporarily experimenting with them.

The History Channel examines the world of LSD with its new documentary, “History’s Mysteries: Getting High,” airing tonight at 7 p.m.

Hosted by Arthur Kent, the documentary takes an in-depth look at LSD, including the drug’s accidental creation, its use by the CIA on unknowing test subjects, as well as its cultural, social, medicinal and political impact.

Aldous Huxley, Timothy Leary and Allen Ginsburg’s experiences with LSD are all chronicled in the documentary, along with interviews with Grace Slick of Jefferson Airplane, “One Flew Over the Cuckoo’s Nest” author Ken Kesey and Dr. Ralph Metner, who was a research psychologist and a member of Timothy Leary’s Harvard group.

The show’s producer, Jonathan Jerald, found that many surprising events throughout history were connected to LSD.

“But most surprising was the extent of secret government experimentation, which included slipping LSD to unwitting subjects and serious consideration of a plan to spray LSD from remote-controlled aerosol canisters in the New York subway to test it as a battlefield weapon,” he says.

According to the documentary, LSD was discovered accidentally by Swedish scientist Albert Hoffman while researching drugs to stimulate blood circulation.

LSD comes from a mold known as rye ergot, which co-mingles the senses, overstimulating a part of the brain associated with the occipital lobe, which creates vision, producing scenes and sensations that, in reality, are not there.

Trips from LSD often depend on the emotional state of the individual. If people are feeling emotionally safe, they may have very pleasant experiences, but if they are emotionally disturbed at the time, they may experience very terrifying, violent trips.

Denise Denton, instructor of health and human performance at Iowa State and prevention specialist for Youth and Shelter Services, knows all too well of the dangers of LSD.

Denton’s first encounter with an emotionally distraught LSD user ended with her lying on top of the girl on a hospital room floor, trying to keep her from hurting herself.

“She hallucinated that she died and that her whole family was witnessing her funeral, and she screamed for hours,” Denton recalls. “It was very difficult to get control of her, because one of the things that sometimes happens with hallucinogens — and this can be true of LSD, it’s not necessarily the most common characteristic — but they get kind of a superhuman strength. It took five of us to hold down a 90-pound 14-year-old.”

The day after an LSD trip, the user may or may not remember tripping, Denton says. Since LSD is absorbed into fat cells and released over time, a person may relapse without even having ingested the drug.

“It comes and owns you again,” Denton adds. “It might happen once a month later, it might happen years later and is sometimes triggered by an emotional episode again. It’s very unpredictable.”

LSD contributed to the cultural revolution and freedom of the ’60s and climaxed with the “Summer of Love” and the scene at San Francisco’s Haight-Ashbury.

“For many, this was a liberating epiphany,” Jerald says. “One result, of course, was the development of new forms of art, music and literature that were perceived as freed from traditional constraints.

“A lot of it was awful, of course, but some of it was pretty good, and it became the foundation for much that is vibrant in the post-modern worlds of art and music.”

This rebellion and liberation lead to experimentation. Individuals checked their merits and re-evaluated their beliefs on cultural norms.

People were “tuning in, turning on and dropping out.”

“The liberating insight that had such a noticeable effect on the arts also encouraged a spirit of social experimentation,” Jerald says. “Traditional ideas about marriage, for example, were abandoned by many. Communal life and casual sex may not have endured, but they certainly forced society to take a closer look at what makes relationships tick.”

Medically, LSD was experimented with in the ’60s and ’70s, but funding for research dried up.

“Nobody ever found a practical medical application for LSD, although [Timothy] Leary’s experiments with prisoners, aimed at reducing recidivism, were encouraging,” Jerald says. “There is some significant anecdotal evidence that LSD could be helpful in freeing addicts of their addictions. Work done in the ’50s and early ’60s with alcoholics was astoundingly promising — but more research would have to be done to confirm those early results.”

LSD was never proven to be addictive or physically damaging, the show says. A lack of research may have attributed to this conclusion though. LSD does distort the perception of the user and can lead to depression and other mental health issues.

The drug was seen as a very powerful and threatening force in the ’60s and ’70s.

“By encouraging a sense of freedom from traditional constraints, LSD was not only perceived as contributing to the development of a culture of liberation, it was viewed by many in the establishment as a subversive substance that undermined loyalty to church, state and traditional mores,” Jerald says.

“LSD has much to offer researchers interested in exploring the human psyche. Even the most psychedelically experienced of our interview subjects, however, warned that LSD should only be taken in a secure environment and under appropriate supervision.”