Stone statues dating back to 1,000 AD suggest it was known to the ancient Mayans in Mexico. The Marquis de Sade, whose name was given to the practice of sado-masochism, described it in his 1791 novel, "Justine."
The more common ways of carrying out the practice are self-hanging, strangulation, choking, suffocation and techniques to restrict breathing movements. Self-hanging is the most common method observed among fatal cases, according to Hucker's Web site, Forensic Psychiatry
"Fatalities resulting from AEA practices occur with a frequency of about one per million of the population per year in North America though it is important to note that this figure is based on studies of cases that have been recognized as AEA or Hypoxyphilia," said Hucker.
Usually a rope or ligature is the method used to strangulate the oxygen supply, but others may be present as part of the person's own sexual ritual. Plastic bags and more complicated apparatuses may also be used.
Sex therapists regard this as a paraphilias -- or a socially unacceptable sexual practice. It is often associated with forms of anxiety and depression, though not suicidal thoughts.
Few who seek help because of the shame, which fuels a cycle of guilt, anxiety and then release.
"Many look pretty normal underneath but when they are accelerating this need for a very intense high, what they are doing in medicating some state of dysphoria or unease," said Coleman. "And because it is rather unusual and there is a lot of stigma around masturbation to begin with, the guilt and shame become part of a repetitive cycle of obsession and compulsion."
Teens often discover the practice on their own, rather than learning it from others. Its sensations are similar to the "choking game" played by young children, who get a thrill from the dizziness created by holding their breath.
Divers have also reported a "high" from oxygen deprivation, according to Coleman. "For some people that may be pleasant or something associated with sexual arousal."
"This has been around long before the Internet.We have no idea how they would discover this," said Coleman. "It's not something they learned. It was a puzzlement and we concluded they were learning it on their own."
"We can only start to piece this together from people who have actually survived," he said.
Coleman, who did not consult in the Carradine case, speculates that many, like the actor, have practiced AEA for years.
"It becomes for them a fetish kind of thing and that is what it really takes for them," he said. But often their activities escalate in risk for the thrill, resulting in accidents.
But in the case of teens, accidental death often happens because they are inexperienced in the practice. "For those who have done it a long time, they know the limits and are pretty careful."
Coleman said people, particularly young teens, need to learn about the dangers of AEA.
"There are a lot of things on the Internet and we have no idea how this is impacting people," he said. "We are certainly concerned that [the Carradine case] might lead to an increase."
"We need to educate people about the risks rather than shield people from the information," he said. "A lot of people are engaged in this activity and they don't know the risk."
Carradine's ex-wife Anderson also said in divorce documents that her "pleas for him to get counseling" were ignored.
Attempts by ABC News to reach Anderson for comment were unsuccessful.
ABC senior researcher Sheelagh A. McNeill contributed to this report.