Someone’s hands tightening around your neck, cutting off blood flow and oxygen to your brain to the point that you feel like you’re going to pass out seems like a nightmare. Or a fantasy.

This is one of many ways to perform erotic asphyxiation, also known as breath control play, the practice of intentionally restricting blood flow to the brain for sexual arousal.

The practice differs from autoerotic asphyxiation in that it is generally performed with a partner as a form of kinky power play rather than alone in your room by self-hanging, the most common method according to Jane L. Uva’s article “Review: Autoerotic Asphyxiation in the United States” in the Journal of Forensic Sciences.

Even though there’s another person present in the room, erotic asphyxiation can be just as dangerous, and it remains one of the most controversial topics in the kink community. Some say that its appeal is its risky nature and encourage safe practice; others say the potential benefits  just don’t outweigh the risks.

It works like this: The carotid arteries on the sides of the neck carry lots of oxygen-rich blood to the brain, so restricting that blood flow produces feelings of light-headedness or giddiness, which heightens sensations during sex and masturbation, according to Columbia Health’s Go Ask Alice column. When pressure is released, the rush of oxygen back to the brain gives a sense of euphoria. People do it by chest compression, a plastic bag over the head, or a cord, belt or scarf around the neck.

Shay, a medical expert who writes a kinky medical advice column called “Private Duty” for Kink-e-Zine and part of StefanosandShay.com, cautions breath control play beginners.

“Breath control play is dangerous and, while there are ‘safer’ ways to do it, that’s kinda like saying there are ‘safer’ ways to race motorcycles – yeah, there are ways to decrease risk, but it is an inherently risky activity and the risk is never going to be zero,” she said. “Still, getting in the car to drive to work isn’t a zero risk activity, few things are, so it’s all about the degree of risk that you find acceptable.”

The real problem, she says, is that beginners don’t know the risks that breath play entails.

“The biggest risk is that this type of play can cause cardiac arrhythmia – abnormal heart beats – that sometimes are harmless, but sometimes can cause you to go into cardiac arrest. This is an inherent risk of breath control, and if you’re doing actual breath control there is no technique that will take this risk away,” she said.

Jay Wiseman, a BDSM expert, who has written extensively about the topic, is known in the kink community for being much more cautionary when it comes to breath control play.

“I do believe, based on studying these activities extensively, that they have a very questionable risk/benefit ratio and that they are both far more unpredictable and far more dangerous than many people understand them to be,” he said in his “Closing Argument” on breath play featured on his website.

Another one of his main concerns is the legal aspect.

“Any harm caused by them is likely to be both medically severe and legally indefensible. These medical and legal risks extend not only to engaging in these practices, but also to both allowing breath play at events one is putting on and/or to teaching how-to classes regarding these practices,” he said in the same piece.

The SF Citadel is hosting a panel discussion on the topic this summer, geared toward anyone interested in practicing breath control play.