Sex and the Brain: How Neuroscience May Soon Change All Our Relationships

You will be reading this because of the headline. You should be happy to know that you are not being misled. You might not be totally happy with the conclusions, but that is for you to make your own mind up.

When we have sex (we being humans, not the author and you, the reader) there are three main neuro-hormones that are released for men and women, and a fourth just for men. These hormones impact the way our bodies behave, and influence our minds and thus our perception of reality.

The first one is dopamine. Dopamine is the pleasure high, the fireworks, our reward. Dopamine is one of the most fundamental neurotransmitters we have. Basically we are dopamine machines. The expectation of dopamine drives our mind to control our body to do things. We think you wanted a coffee to perk yourself up, but in fact it was a dopamine cycle that kicked in to make your body get up and find a coffee to sate the dopamine expectation.

The next is serotonin. Serotonin is serenity, ecstasy and the state of grace. It is the lingering pleasure sensation we get that is less intense than dopamine, but nonetheless a powerful driver for our behaviors. Serotonin is about feeling good, really good.

The third, for both men and women, is oxytocin. Oxytocin is the bonding agent, the cuddle chemical. This bonding agent makes us want to connect, physically, with another person. And once connected, stay connected. It is a powerful force, one that men sometimes complain about “she wanted to cuddle, I needed to get to work”, and women too “… and then he just left me”.

Oxytocin can be easily fabricated, just with close contact to another human being (or a pet). Just twenty seconds of hug contact, even with a stranger (with a tolerable level of body odor), can dramatically boost levels of oxytocin. It is very much the bonding glue for humans.

The fourth chemical is a male neuro-hormone, vasopressin. Vasopressin is the protection drug, one that kicks in to support feelings of possession and desire to thwart anyone else taking possession. This is now the knight in shining armor threatening to skewer any rival that comes near (or more realistically, the inner thug who would bash someone over the head).

So we have two people (or more, depending on how extreme your lifestyle might be) engaging in a deeply sexual act, and inside the brains you have a rush of chemicals. These chemicals control our bodies response to the act.

Moreover, the recollection of this chemical experience will be encoded into our memories so that if we dig back in our minds to experiences past, we can regain at least a part of the actual feeling experienced at the time.

Now for some controversy, and this is all based around our vital bonding agent, oxytocin.

When you continue to have sex with the same person, there is a build up of oxytocin. You may have noticed that you become closer and closer to a person in the first months of meeting them. There is (hopefully) a desire to see the other person again, to be bonded, and to deepen that bonding. Hence the desire to go on holiday together, do more things together, spend more time in each other’s company (which also prevents someone else sneaking in).

Oxytocin has its own expectation effect. Just like the quest for dopamine, there would be a desire to get another oxytocin hit, a friendly hug perhaps, or more. Oxytocin itself becomes addicting and with continued presence of another specific person, this becomes encoded to the other person.

Oxytocin helps bond and maintain bonds even if there is no good sense to other aspects of the relationship. One can remain blind to these faults if oxytocin is maintained. And that means continuing sexual relations with your partner.

Those of you in longer term relationships, more than two years, will probably have experienced the distance that is created if one does not maintain a sexual relationship. In some cases, this morphs the relationship into a best-friend partnering. At worst, lifting the veil of oxytocin gives one person in the couple, if not both, the opportunity to see the person in a new, more rational light. That often ends in a break up, or a much more argumentative relationship with few benefits.

Whilst oxytocin must be maintained, it has a more dampening impact on sex itself. Over time, as oxytocin between a couple builds up, it reduces the impact of both dopamine and serotonin. This would happen anyway as habit builds up in our neuro-systems, so things become less novel, and practical couple issues become more prominent (such as “who is going to take the kids into school tomorrow”). Therefore as oxytocin builds up, sex is just not as fun any more. Certainly not in comparison to the highs of the first months, and maybe couple of years of a sexual relationship.

One other function of oxytocin is even more controversial to those who believe in true eternal love. Oxytocin not only bonds people together. It also, on ‘first use’ has the effect of erasing the memories of the previous partner. If you think about it, this is a handy survival mechanism. In ancient times, you can imagine your first true love, a hunter of saber tooth tigers, lying dead in a ditch, or your wife dying in childbirth. Life without a partner can be significantly more stressful than life with one.

Men have an intuitive understanding of the erasing effects of oxytocin. The most natural response for a guy on break-up is to find someone else to sleep with. This response helps them overcome their feelings of loss, whilst starting the bonding process with another person. Of course, men are also aware of the potential vulnerabilities they might experience, hence the caution over rebound relationships.

As for love, this is a much wider topic. Somehow though, it feels unfair or just plain wrong to discuss sex without love.

For simplicity’s sake, we will cut short a deep discussion and focus on some core points. Love as a behavioral pattern has a component of desire, an element of pleasure, a need for closeness, and a sense of desperation or anxiety. Fortunately there are good neurological reasons that can explain these experiences, even if they might seem cold-hearted to some.

In seeking a new partner, we may find ourselves attracted to someone. The expectation of the dopamine and desire for serotonin and oxytocin are powerful motivators to find someone to connect with. Even at this early stage, our memories start creating a platform, a structure, for us to fall in love at some point in the future. Our memories are stored in an associative way. We do not store things like a computer, all facts and data points. Instead we store memories as a synthesis of different experiences and emotions, combining facts – our interpretation of facts – with feelings. For the strongest memories, we have an extra chemical charge that is attached to these original feelings. This makes it more likely that the memories will be retrieved, both because they are more intense, and because they give us new pleasure.

Furthermore our mind plays tricks on us. I remember once being told by a girl in the US that when she met a guy she really liked, she would start imagining her first name attached to his last name. Her mind was creating a fantasy world, one where they would go on holiday, set up house, get married, have kids, and grow old together. Her brain, though, has a tough time separating reality from fiction, and these imagined events get associated with the real person. From the first time we meet, we have a parallel imaginary vision of the person, and these imaginary events too become part of our memories.

Thus we become encoded to another person. Our experiences in real life that give us pleasure become memorable. And our fantasies reinforce and go beyond even these memories to create additional layers of desire, affection and closeness.

At the same time, we experience the pang of potential loss. When we are stressed, our bodies release cortisol, the stress hormone. When we are stressed, our whole body can get stressed as the hormone can impact the functioning of the heart and lungs. A simple act can trigger these emotions. An absent ‘goodnight’ text or call. A thirty-minute delay arriving at a restaurant. Checking on the person’s Facebook page and seeing another boy or girl’s flirtatious comment on a Wall.

Stress and its counter-part, stress relief, also are strong emotions that get encoded into our memories. In spite of stress being a largely negative concept, the very fact that we experience this sense of loss associated with a person who also has the stored notion of pleasure and comfort merely adds to the overall mental picture of the person.

Added to that and the connection between our hypothalmus and the control of our key body organs, it is not surprising that our heart feels heavy if we feel sad about a loved one. Or that our heart ‘skips a beat’ when we get ready to meet our (new) partner again. Our brain controls our bodies in a way that is hard for us to control or overcome.

Thus we end up with some simple factors, and some perhaps shocking conclusions. When we find a partner and become physically close, we become bonded to them. We develop strong associative memories of that person, flash-encoded with the rush of dopamine, serotonin and oxytocin that is released in sex. We experience a sense of anguish if something goes wrong, and this sense of anguish when tied to the sense of pleasure leads us down a path of love.

As we spend more time with the person, this becomes boring, certainly in relation to how things were in the first days of contact. As things become boring, we then either settle into a more comfortable type of relationship based on bonding and minimally sexual closeness, or seek to make our lives more exciting again (bond-age perhaps?).

One way that we reinvigorate ourselves is by seeking out and connecting with new partners. This new coupling experience helps us overcome our sense of loss at the old partner, and restarts the bonding process with someone new.

Our brains do have another coping mechanism, an extra neurohormone called prolactin, to help those manage a long-term relationship. This hormone is associated with satiation and resignation. This is the chemical signal for us to give up, the same chemical that turns wild tigers and cheetahs into zoo zombies. So, instead of making the effort to find a new partner, which would cure some of the sexual urge, we pump our brain full of prolactin drugs to make us forget we ever wanted sex in the first place.

The implications for this are either sensible or disturbing, depending on your viewpoint. On the one hand, it makes most sense to allow for freer, non-sexually exclusive relationships. Everyone who has had a positively good long-term partner knows that a relationship has many different aspects to it, of which sex is just one component. Our one hundred and fifty year obsession with monogamous marriage deserves to become a relic of an older age, just like the land line telephone or a manual typewriter. Societal pressure to be with one person for ever, even if the partnership is unhappy, creates unfairness for many, many people. From this perspective it is easy to understand the 45% divorce rate for all marriages, excluding the marriages that have either occasional or habitual affairs from one or both parties.

On the other hand, reducing human beings to a sense-less set of rules and chemicals seems unhuman somehow. It seems more comfortable to expect that love exists, that falling in love is a special, personal feeling, that one can be with another person in blissful happiness forever. Many young women I speak to (younger than thirty typically) can only imagine a relationship lasting a lifetime.

And yet, for these people, their expectations may be set more by television and movies than by real life. Usually they ignore their own personal experiences, and discount them in favor of a fairy tale. A woman who has dated a lot of men early in her life looking for the right partner (or just enjoyment) may find that she has actually programmed herself to becoming bored with any one person.

However, taking a scientific approach does not mean that one cannot be human. The knowledge of the neurochemistry of sex and connections should not make a connection any less magical. And that is because fortunately, in key moments, our brain cuts off our rational mind and jumps in to rescue ourselves from loneliness. So, even if part of our brain is on constant watch for the tell-tale signs that we will be overcome by neurochemicals, another part of our brain has got a fast-track mechanism to the off-switch to turn the monitoring system off. Sometimes that is alcohol, or other mood altering substance (or context). Sometimes it is our own rational mind realizing that it too needs a break and wants to relax.

So, the next time you have sex. The next time you think about having sex. The next time you imagine your lover doing whatever you want them to do. The next time you get annoyed at them not doing it. The next time your eyes start wandering to look at other attractive people. The next time. Be aware that your brain is active, giving you support, direction, and a reward. Good luck out there.

12 Responses to “Sex and the Brain: How Neuroscience May Soon Change All Our Relationships”

  1. I found this post fascinating – can you point me to some sources for further reading (even if they are technical)? I had no idea that such studies of neuro-hormones existed, but I definitely think they are essential in understanding human sexuality at the next level.

  2. This was a great read, and provided some good technical information while holding one’s attention. It also explains why the the wife and I have both benefitted from being active in and knowing other couples in the Lifestyle. That “emotionally monogamous” but sexually non-monogamous lifestyle has kept all the best parts churning for us, and it’s actually drawn us closer together even as we have strong bonds with other couples now, too. It’s just that none of them have had a chance to rise to the level of ‘replacing’ our relationship, but this article does explain why that thrill remains for us sexually as we’ve grown older. In our 60’s now and still having sex up to a half dozen times a week, and we know it’s because of the biochemical activity that is working in us to keep sex fresh.

  3. Wow, thank you so much for writing this article. I love it.

    I have a friend who is addicted to abusive relationships.

    Are there “happy hormones” treatments? Assuming she has a deficiency

    • Interesting challenge 🙂

      I don’t know that much on hormone therapy (would need to Google!). I have looked at Cognitive Behavioral Modification… how you can start to program yourself to different patterns.

      There is a strong notion, though, about what your role might be as regards your friend. It is almost impossible to get inside a person’s head, and even if you sneak in, the person may change. My personal view is that we live our life through our own lives… that our reality is based on our own experiences. Therefore, if your goal is also ‘be happy’ and ‘limit being sad’ (basic!) then it is plausible that your friend has needs to be ‘needy’ and you are being used to help her out in her own life. If this impacts your own life, then you need to decide if she brings enough happiness to make her sadness worthwhile. If the answer is ‘NO’, then maybe she is an emotional vampire and should be ejected.


  4. Excellent article….when I am counseling couples I tell them that monogamy is a human choice not a biological one. Therefore working on the sex in a marriage is so vital…to keep the stimulated as well as the body.

    • I feel bad for you, to counsel couples and have such little understanding of marriage. The article, although pretty accurate when it comes to the brain chemicals, misses the entire point when it comes to their purpose which God Himself intended for our benefit. Oxytocin is the “bonding” brain chemical, intended to “bond” one man to one woman for life. Hence the word “bond”. When two become one. When you leave the author of life and marriage out of it, you get what you got…

      • An interesting perspective. I come from the stance of being a firm atheist since I was in my teens, and nothing has changed my viewpoint since then. As I don’t believe in some mega-being, I obviously would not put the contxt of the bio-goings on of our brains and bodies in the realm of the supernatural. Though I have experienced some sexual activities that indeed become spiritual and vast in terms of connectedness with the universe (generally considered to be a ‘very good thing’).

        God< were she to exist, does a pretty crappy job of making our current monogamous marriage proposition work. With a failure rate globally of nearly 60%, I would imagine that they have decided to duck out of the whole thing and leave those humans to get on and do whatever they are going to do.

  5. Very interesting read. Thank you.

  6. what is your source?

  7. Awesome!! Totally a fab post. 🙂


  1. Serial Dating Problem and the Switch to Monogamy #MayFail | Mark Turrell - Changing the World... - April 20, 2012

    […] as the various pleasure chemicals get encoded into our memory banks (see my past blog post on Sex and the Brain). Even the crappy times are still hyper […]

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