Sex & Relationships

Why Sex Feels Good (and Why It Can be Stressful)

Sex is a boom and bust way for you to get the brain chemical that makes you feel relaxed and secure.

The following post first appeared on Psychology Today. 

Sex feels good because it stimulates oxytocin, a brain chemical that produces a calm, safe feeling. Oxytocin flows in apes when they groom each other’s fur. Sheep release oxytocin when they stand with their flock. Lizards produce a variant during sex. When someone has your back, or you have theirs, your oxytocin is flowing. Social trust promotes survival and the mammal brain rewards it with a good feeling.

Sex triggers a big jolt of oxytocin, but it’s soon gone. Once it’s metabolized, you feel endangered, like a sheep without a flock. Our brains keep seeking oxytocin because that promotes survival in the state of nature. A sheep survives in a world full of wolves if it sticks with the flock. An ape survives if it has reliable allies. A lizard's genes survive if it finds mates. Natural selection produced a brain that feels good with oxytocin, and bad without it.

Elderly people holding hands on a park bench are stimulating oxytocin. They don't get enough for spikes of ecstasy, but enough to protect them from extremes of insecurity. Unfortunately, holding just any hand does not work. The mammal brain is very picky about when it releases oxytocin because misplaced trust threatens survival in the state of nature. Apes are known to bite off the fingers, toes and even the scrotum of a troop mate. Lizards can get eaten by individuals they approach for sex, and lambs succumb to predators cloaked in the scent of the flock. Getting close makes it easy to get hurt. Our urge to trust could get us into trouble were it not for nature’s alarm signal: cortisol. This chemical is often equated with stress, but it's the primitive brain’s pain signal. Betrayed trust leads to physical pain in the state of nature, so your cortisol siren is triggered when your trust is betrayed.

We are left with a terrible dilemma. Our brain craves the good feeling of trust, yet it avoid things associated with past pain as if your life depended on it. Humans have struggled with this brain since they first walked the earth. In past millennia, people relied on fixed social bonds to stimulate their oxytocin and ease their cortisol. They formed tribes, clans, families, and pair bonds with sharp distinctions about when to trust and when not to trust. Maybe you got bitten by the people inside your trust circle, but survival without them seemed impossible. You rarely got to pick and choose your trust bonds, or build your own from scratch, or take a chance outside established trust networks.

Today, we want more. We want big surges of oxytocin with no stabs of pain. We leave behind the imperfect social bonds of our youth in the expectation of something better. But it turns out that trust bonds are harder to build than we expect, especially after the neuroplasticity of youth. We shop for oxytocin and get disappointed sometimes. As disappointments accumulate, our brains keep alarming us with pain signals. What's a modern mammal to do?

You Can Rewire Your Oxytocin Circuits

When your brain looks for oxtyocin, it relies on neural pathways built from your unique life experience. Your past oxytocin flows paved neural pathways that help your brain trigger more in the future. If you enjoyed social trust while playing chess with old men in the park, or getting your nails done at the corner salon, neurons connected that trigger the expectation of social trust from similar experiences. If you enjoyed oxytocin in loud bars or in quiet living rooms, you wired yourself to find more of the same.

Early experience built the superhighways to your oxytocin because neurons connect easily in childhood and puberty. The trust you experienced with your family and schoolmates wired you to expect trust in that way today. Maybe you built trust by going to the liquor store for someone. Maybe you built trust by not going to the liquor store. Whatever stimulated your oxytocin installed an app in your brain. You can install a new app if you know how your brain works.

Cortisol paves neural pathways that warn you to avoid things that have hurt you. When you’re disappointed by someone you trust, your brain builds warning signs of potential pain. Cortisol makes you feel like you're in immediate danger. You don't realize that social pain is part of every mammal's life. Animals often bite a troop mate who gets in their way. By the time a young mammal is grown, it has experienced enough bites to build a pain-avoiding neural network that keeps it safely out of the way of bigger troop mates. The mammal brain is constantly deciding when it's safe to trust and when it's not safe to trust.

We are doing better than we realize. We have built a world in which strangers work together toward common goals without biting each other. Once we achieve the goal, we move on, in the expectation of building new trust with new people. We don’t realize what a big accomplishment this is because the social bonds of the past have been idealized. In-group violence was widespread in the past. People stuck with their trust bonds because life without them seemed even more dangerous (and often was).

Sex was constrained by rigid trust bonds in the past. Sex led to babies, and babies don’t survive without huge trust bonds. Sex was restricted in ways that promoted the survival of babies. Hook ups could destroy your trust bonds, so you’d lose more oxytocin in the long run than you’d gain. An immediate blast of oxytocin is tempting, of course. But once you get it, it passes quickly and you’re left feeling like something is wrong. The fast, easy road to oxytocin often feels bad in the long run, but social bonds that are forced on you feel bad too. Your brain feels best when you have trust bonds that built up from many one-to-one experiences over time.

This is hard to do because we mammals easily get in each other’s way and trigger each other’s cortisol. If you run from every alarm bell, you may never build trust circuits that are big enough to survive the everyday annoyances of a mammalian herd or pack or troop.

Trust builds from an accumulation of small experiences. Each time you enjoy the trustworthiness of another person and offer your trustworthiness to them, your neural pathway builds.


Loretta Graziano Breuning is professor emerita of management at California State University, East Bay.