Amanda exhales a wavering moan as the needle pierces the flesh on her forearm — in one side, out the other.

When the body modification artist steps back to admire his work, a small metal bar bookended by two stainless steel balls adorns her skin. In a few minutes, it’ll be used as a makeshift grommet for a corset of ribbons strung together by a series of identical piercings … like lacing up a shoe, but on someone’s arm. The artist dabs a blossoming jewel of blood emerging from the wound with a paper towel and gets back to work.

Though her fists are clenched white, Amanda is glowing. From where I’m sitting, it’s unclear whether she’s moaning in pain or pleasure, but, then again it doesn’t really matter. For the many people who experience sexual gratification from physical discomfort, there’s a razor thin line between the two sensations; one that, when skirted correctly, creates an intensely satisfying high and release.

Play piercing, or needle play, is one way people like Amanda chase that singular feeling.The practice falls under the “S” and “M” categories of BDSM (sadism and masochism) — umbrella terms to describe activities in which people gain sexual gratification from either giving or receiving pain. Nationwide, about 10 percent of people of take part in this kind of play, making it one of the more popular kinks out there.

Typically, S&M acts are done for the purpose of enjoying the experience rather than permanently modifying the body. In the case of needle play, all piercings are removed when the scene is over and the wounds heal with minimal scarring. Usually, those who get into this kind of stuff do so for self-expression, self-discovery, or, in Amanda’s case, for sexual pleasure.

“It makes me feel beautiful,” Amanda tells me, looking down at the series of piercings on her arm. “It’s such an extreme submission — I’m literally giving my body to whoever is piercing me, but in a way that makes me feel beautiful, not degraded.”

She likes how piercing toys with the concept of penetration — what does it mean to be inside of somebody, or to transcend their outer visage to touch a more inwardly organ?

When the needle pierces her skin, she feels a gush of pleasure that she finds extremely erotic. It’s not the same good feeling she gets from sex, or a massage though — it’s a different kind. She says it’s more universal; sharper. And while it does sometimes hurt at first, she notices that the pain often morphs into feeling of what she calls “relaxed gratification,” a state where she feels totally calm, receptive, and blissed out. After a few pricks and piercings, it doesn’t hurt at all.

Sometimes, when she’s in that state, she’ll masturbate or, if her partner’s around, have sex.

“My orgasms are stronger after I’ve been pierced,” she tells me. “I’m more relaxed. I’m already buzzing and euphoric. All my blood is pumping from the adrenaline.”

If that seems strange in any way to you, it's actually not. This shift — from pain to pleasure — is actually a well-documented aspect of not only play piercing, but of many things, sexual or otherwise.

In the context of an S&M scene like play piercing, consensual pain can produce an intense natural adrenaline and endorphin high that’s been known to produce orgasm and last for hours.

This is because when your body experiences stress or pain, your hypothalamus and pituitary gland squirt out supersized doses of endorphins — as well as other happy hormones like melatonin (for relaxation) and serotonin (for euphoria) — in order to kindly kill the hurting sensation, explains J. Kip Matthews, Ph.D, a sport and exercise psychologist to Healthy Place. Endorphins, he continues, are structurally similar drugs like morphine and heroin, and are considered natural painkillers because they activate opioid receptors in the brain that help silence discomfort. In doing so, they also can also cause euphoria and can bring about feelings of general well being.

“Endorphins are also involved in natural reward circuits related to activities such as feeding, drinking, sexual activity and maternal behavior,” he says.

Explains why many of us like a slap on the ass during sex, no?

The pleasure-from-pain high is hardly unique to kinksters, though. It’s much more common than you’d think. In fact, it’s the exact same high as runner’s high, the identical, yet much more accepted phenomenon where the physical pain of intense exercise leads to short-term emotional bliss. An endorphin and adrenaline rush are also hormonal changes you experience when you’re falling in love (or just really horny), and when you eat really spicy food.

So, chances are if you’ve experienced runner’s high, had any sort of romantic tingle for someone, or painstakingly enjoyed a really hot curry, you have more in common with the sadomasochistic than you may think.

That doesn't mean you should go running out of your house to try it, though. Sadomasochistic pain play is delicate negotiation between experienced and consenting parties, and should never be enacted without taking the proper steps of communication and preparation first.

As Slate's William Saletan writes, "S&M, by its nature, hurts people. Mild bondage is no big deal. But for sadomasochists, pain is the whole idea. Some stick to spatulas and wooden spoons, but others move on to electric shocks, skewers, knives, and butterfly boards. Women who do S&M porn scenes have described electrical burns, permanent scars from beatings, and penetrations that required vaginal reconstructive surgery. While these injuries were accidental, the BDSM subculture doesn’t regard intentional harm as wrong. According to the 'Statement on Consent' developed by the National Coalition for Sexual Freedom, injury is wrong only if it 'was not anticipated and consented to.'"

Meanwhile, Amanda's arm corset is complete. Each puncture in her skin is surrounded by a small, but angry ring of red inflammation, but admittedly, it looks beautiful.

She tugs on the ribbon a bit so that the piercings stretch the already-irritated skin on her arm.

"Ouch!" she exclaims, grinning up at me, her pupils dilated in post-pain rapture. "It hurts so good."