Feb. 14, 2008 -- A Canadian college professor spent three days in a coma over the weekend after losing consciousness in a New York sex club where he was left alone with a dog collar around his neck and a leather hood over his face, according to a report in the New York Post.

The man, identified by the Post as Robert Benjamin, 67, was found passed out last Friday by a dominatrix in a sadomasochism club called the Nutcracker Suite. The dominatrix noticed that his foot had turned blue after the high-heeled shoe he was wearing fell off, according to the exclusive report in the Post.

Law enforcement sources told the Post that Benjamin, whose fetish was to be bound in S&M gear and then left alone, lost consciousness when the oxygen flow to his brain was cut off while he was hanging from his arms.

Benjamin was rushed to Manhattan's St. Vincent's Hospital early that morning and regained consciousness Monday, promising to come clean to his wife and never engage in dangerous sex again, the Post reported.

St. Vincent's confirmed on Wednesday that Benjamin was still in the hospital, but the Montreal native did not return calls from ABCNews.com placed to his hospital room.

Compared to a series of recent incidents in which practitioners of dangerous sex died to satisfy their kink, Benjamin, who was reportedly a regular at the club, was lucky.

Mixing Pleasure and Pain

Sadomasochism encompasses a broad swath of sexual interests, but always involves a certain degree of giving or receiving pain in the interest in sexual gratification. In some cases, it can be deadly.

Last October, a medical examiner determined that the Rev. Gary Aldridge, a 51-year-old Baptist minister from Alabama, died from accidental asphyxiation while pleasuring himself. He was found wearing two wet suits, a face mask, diving gloves, slippers, rubberized underwear, two ties, five belts and eleven straps, according to the medical examiner's report.

In April 2006, British national Adrian Exley suffocated to death in the closet of a Rhode Island man whom he had met online. Exley was wrapped tightly in heavy plastic and bound with duct tape, and a leather hood was over his head. Gary LeBlanc, the man who tied Exley up, in a sex act both men had consented to, later committed suicide, according to The Associated Press.

The "Janus Report on Sexual Behavior," one of the premiere academic surveys of sex practices, found in 1993 that 14 percent of men and 11 percent of women have had some sexual experience with sadomasochism.

But sadomasochism is difficult to define. Some practitioners engaging in highly dramatized "play" that has more to do with theater than pain, while others look to be severely tortured, said Martin Weinberg, a sociologist at Indiana University who has studied sadomasochism clubs.

"There are two forms of SM. One is a sociological phenomenon and is more about socializing with other people. People go to a club for recreational, theatrical fun. The other is a psychological phenomenon. Something in someone's biography leads them to seek out SM," he said.

"Psychological cases get into heavy pain. They pay for dominatrices and ask for extreme pain like having pins stuck in their scrotum. People paying for dominatrices are not socializing with other people, they are in it purely for the pain," he said.

The AP also reported on a case in which a man allegedly died under circumstances not unlike those that led to Benjamin slipping into a coma. In January 2006, dominatrix Barbara Asher, 56, was acquitted of manslaughter in Massachusetts in the death of a man who allegedly suffered a fatal heart attack while strapped to a replica of a medieval torture device.

S&M Clubs Spring Up

Some forms of sadomasochism and the related fetish of bondage sex have gained a certain degree of normalcy. Clubs have sprung up across the country along with shops catering to fetishists in most major cities.

Every year in San Francisco, some 400,000 people attend the Folsom Street Fair, an outdoor festival dedicated to the safer and more commercial aspect of sadomasochism, according to the event's Web site.

"There are multiple organizations across the U.S. and internationally that educate people about safe play and kinky sex," said Vincent Andrews, president of the National Leather Association, a network of S&M community organizations.

"Almost every major city in the U.S. has a BDSM (bondage-sadomasochism) event geared towards safe play," he said.

But for some, "safe play" is the opposite of what they're looking for.

Enhancing Orgasm

"Some people cannot experience pleasure. They can only experience deep feelings when they are truly painful," said Judy Kuriansky, a sexologist and psychology professor at Columbia University. "Everyone is looking for some sort of sensation. For true masochists that experience becomes distorted and they can only feel something when it hurts."

Kuriansky said masochism is more about power than sex and that events in one's early childhood could prime a person to associate pain with sexual gratification.

In addition to pain, she said many masochists find pleasure in choking themselves or being choked, because the sudden rush of blood to the head can produce a euphoric high and enhance orgasm.

Benjamin told the Post that the experience of being comatose was enough to scare him off from dangerous sex in the future.

"It's like when you crave turkey," he told the paper. "You eat it and you it and eat it, but you still want it. But now I've had enough. I don't want turkey anymore. I'm full … I don't want to go to clubs anymore. I'm trying to learn to control myself and my emotions."

But simply having a wake-up call, no matter how startling, is not always enough. Kuriansky said it was rare for a masochist to finally become capable of associating sex with pleasure and love instead of pain and danger.

"There is a triumvirate of guilt, embarrassment and fear of intimacy for these people," she said. "It is rare that all of a sudden they can give up on being interested in pain and suddenly be capable of being loved."