See Forbidden Sex Research: The Orgasm Cycle for some updated information about the points made here.
I am very interested in the attraction-repulsion dynamic in intimate relationships — and I am wondering what role, if any, the neurochemistry of orgasm (sexual satiation) may play. Various recent studies have demonstrated a "fall off" in mutual attraction between intimate partners at about two years. For example, testosterone levels diverge in men and women over that period, nerve growth factor drops off at about two years. 1
Yet it is not uncommon for partners to experience an almost immediate desire to get away from a lover after sex. Think of Billy Crystal talking to a male friend in When Harry Met Sally, "30 seconds after I make love to woman I want to run away." I've heard similar statements from some women: "After orgasm I don't want my husband to touch me; I retreat to my side of the bed."
An Ohio State University study 2 showed that, even among the most well-adjusted newlywed couples, the glow had faded by the second year of marriage. Helen Fisher found that actual divorce peaked in year 4 across 58 cultures, except in Muslim cultures where divorce was acceptable…there it peaked much sooner.3 Clearly many relationships erode early on. For the purposes of this discussion, never mind possible individual psychological explanations. What could be going on in our mating neurochemistry that might account for this phenomenon? And could it also be affecting the long-term health of our relationships? Is it possible that the "two-year" drop off is avoidable?
Oxytocin - One thing that usually happens in both men and women at orgasm is a sudden rise (and swift fall) of oxytocin, "the bonding hormone." Within minutes of orgasm it returns to baseline levels in both sexes. What purpose does this spurt serve? Journalists often imagine that it bonds us. But if the purpose of this orgasmic burst of oxytocin is to bond us, it seems to create a very undependable bond - unlike the parent/child bond, guru/devotee bond, or even a bond with a pet, all of which are probably also dependent upon oxytocin.
Some researchers have surmised that this orgasm-related jump in oxytocin has little to do with bonding, and is rather related to orgasmic contractions (oxytocin is associated with other smooth muscle contractions like labor and milk letdown). 4 Or, perhaps, that this jump creates feelings of satisfaction, or even satiation. Why then is it so brief?
Prolactin - Although oxytocin usually rises at orgasm, there is one neurochemical event that is considered an even more reliable marker of climax in both sexes: a rise in prolactin. 6 Prolactin levels remain high for as long as they have been tested (60 minutes). Prolactin, of course, does many things in the body, but after orgasm it appears to act as a sexual satiation mechanism. (It does not rise following sexual activity without orgasm.)
I find it intriguing that other research about prolactin (not in connection with sex) reveals that high prolactin is associated with many symptoms that match exactly what lovers complain of as their romances go sour: declining libido, mood changes, weight gain, hostility (in women). (The hostility was particularly noted in women who did not have tumors in the pituitary. 7 I wonder if these women were suffering from relationship stress — more on that below.)
Prolactin is also associated with long-term stress and despair. Newly-caged wild monkeys showed high cortisol levels, but as the hopelessness of their situation caught up with them, prolactin began to rise. It was highest in those caged longest, even seven months later. 8
Women whose relationships are not going well show surprisingly high levels of oxytocin, which do not counter their stress. 9 (Generally, oxytocin has been shown to counter the effects of cortisol, as well as depression and addiction.)
I wonder if it will turn out that the prolactin levels of these women with relationship distress are also abnormally high. Oxytocin and prolactin interact a lot in pregnancy, birth and childrearing. Perhaps they do here, too. (Post-orgasmic prolactin surges have now been found in women.)
Dopamine - A third neurochemical event that accompanies orgasm is a dramatic rise in dopamine in the reward circuit, which drops sharply after orgasm. Low dopamine can produce uncomfortable psychological effects. 10 And dopamine and prolactin have an inverse relationship. As my husband puts it, "dopamine seems to be the foot on the gas, prolactin a foot on the brakes."
Low dopamine is a key part of any addictive cycle. After an intense high, it drops unnaturally low. At that point, the addict often desperately seeks relief, usually in the form of another dopamine-elevating activity or substance (orgasm, alcohol, gambling, drugs…). It appears that we have evolved to remain in an addictive cycle of highs and lows where sex is concerned, unless we learn to make love in a more deeply satisfying way.
Testosterone - Testosterone receptors decline for up to a week in sexually-satiated male rats. 11 Perhaps humans experience similar, long-lasting changes. I believe that the sexes have much in common in their post-orgasm neurochemistry…but I also think there are different tendencies, perhaps due to the fact that women make more oxytocin naturally, and the fact that men have more testosterone. (More on this point)
The problem of projection
Whatever the gender, our theoretical post-orgasmic lover sees the relationship through a neurochemical haze: high prolactin, low dopamine, baseline plasma oxytocin, and (possibly) fewer testosterone receptors. It is worth noting here that healthy levels of both dopamine and oxytocin seem to be required to maintain a strong pair bond, so when dopamine drops it may affect a couple’s emotional tie. Certainly, this neurochemical combination feels vastly different from the pre-orgasmic neurochemical cocktail of high dopamine and low prolactin.
This brings me to the most critical point that researchers tend to overlook. How we feel has the potential to change how we perceive our partner and thus how we behave toward our partner. So for example, if post-orgasmic low dopamine and high prolactin leave us feeling depleted or needy for a time,12 then we will tend to see our partner as overly-demanding or selfish and insensitive. (And if our partner is in the same state, he or she may actually temporarily be selfish or needy.)
I wonder if this perfectly natural change in perception - brought on by projection stemming from the neurochemical changes inherent in fertilization-driven sex - is at the root of the "repulsion" phase of the "attraction-repulsion" phenomenon.
Over time, as the amygdala begins to associate one's lover with these unfortunate perceptions, one may even naturally become defensive and resentful toward a lover. Perhaps this explains why the honeymoon generally only lasts a year or so. Mankind assumes that the orgasm cycle is "foreplay and orgasm…end of story." But having observed our own behavior for years (in connection with exploring Daoist lovemaking in which orgasm is avoided), my husband and I believe that the orgasm cycle is far longer at a neurochemical level. We have noticed mood swings, emotional friction, and addictive cravings as far out as two weeks after orgasm.
We have also noticed that when we are consistent with the practice, our relationship is remarkably harmonious, cravings are less, and my husband's chronic depression is absent (he was able to stop a six-year course of prescription antidepressants a year after we got together, over a decade ago).
While no tests have been done on the neurochemical effects of orgasm as far out as two weeks (it would be very difficult to do so, given the many variables that affect levels of the key neurochemicals), we did find research showing that prolactin surges for two weeks in female rats after mating, whether or not they become pregnant.13 Also, addicts withdrawing from cocaine (high dopamine activity) have unusually high prolactin for about two weeks.14
Since brain scans of men having orgasm resemble brain scans of people shooting heroin, 15 and testosterone receptors decline for up to a week in sexually-satiated rats, 16 it is quite possible that the body does take a while to return to homeostasis…and that partners' perceptions of each other often suffer, off and on, throughout that period. Our best guess is that prolactin may be one of the chief culprits, at least in women, and that it may surge up and down before returning to baseline levels, which would account for mood swings during that time. Also see Men: Does Frequent Ejaculation Cause A Hangover?
Why a built-in separation mechanism?
Why would evolution neurochemically engineer us to sour on our partners after engaging in fertilization behavior? To improve the genetic variety of our offspring - as is the case for almost all other mammals on the planet. Mankind assumes that it's designed to form stable pairs to make us better parents, but our brains evolved while we lived in tribes. Pair-bonds may have presented little advantage where children were raised, in effect, by an entire tribe. (Certainly two hunter-gatherer tribes, the Kung! And the Mehinaku, show the pattern I'm describing: lots of romance and sexual relationships…and lots of churning in relationships and heartache.)17
It's also likely that we evolved from species that had fixed estrus periods, and it would not be surprising to discover that prolactin — a neurochemical closely tied to pregnancy — is still, indirectly, the mechanism that moves us on to new (or additional) partners by turning us off of old ones. (We believe that the neurochemistry behind this mechanism is behind the Coolidge Effect. 18) Indeed, perhaps this mechanism that tarnishes our perception of a partner after particularly intense sexual stimulation is part of an old "binge trigger" related to mating season from before our ancestors became pair bonders.
Finally, I’ll crawl way out on a limb and admit that I wonder if prolactin may play a role in some people's urge to move toward seeking increasing sexual stimulation. Research shows that prolactin rises 400% more after penile-vaginal intercourse than after other types of orgasm. This was hailed as proof that it was more satisfying. I think a better description might be "more satiating." If one is sexually frustrated, then "relief" might seem like satisfaction, but too much such "satisfaction" may actually decrease libido at least toward one's partner — due to the projection problem mentioned above. Perhaps Friedrich Nietzsche was onto something important when he said: Ah, women. They make the highs higher and the lows more frequent.
Sex play without penile-vaginal intercourse (PVI) may feel less depleting (and therefore more appealing), because it does not produce the same dopamine-suppressing neurochemical "hit" as fertilization-style sex. (Is it because the "job" isn't done yet that prolactin levels don't rise as high?) Sexual play sans PVI could still be addictive with a novel partner partner (due to the addictive dopamine high/low cycle), but the aftermath might not be as…unsettling…at a gut level due to less prolactin.
Anyway, there you have my question:
Could the neurochemistry of orgasm (via projection) play a role in the attraction-repulsion dynamic so often experienced in intimate relationships?
Thanks in advance for any thoughts that anyone may have to offer below.
- 1. Raised Plasma Nerve Growth Factor Levels Associated With Early-Stage Romantic Love, Hormonal changes when falling in love, Sexual Motivation and the Duration of Partnership
- 2. Marital Stress: Immunologic, Neuroendocrine, and Autonomic Correlates
- 3. Anatomy of Love by Helen Fisher
- 4. Oxytocin Mediates the Estrogen-Dependent Contractile Activity of Endothelin-1 in Human and Rabbit Epididymis
- 5. Oxytocin does rise in rats' brains for hours after mating. It appears to make them engage in riskier-than-normal behavior. See Centrally released oxytocin mediates mating-induced anxiolysis in male rats
- 6. Orgasm-induced prolactin secretion: feedback control of sexual drive?
- 7. Psychological distress in patients with hyperprolactinaemia
- 8. Physiologic manifestations of stress from capture and restraint of free-ranging male African green monkeys (Cercopithecus aethiops)
- 9. Relation Of Oxytocin To Psychological Stress Responses And Hypothalamic-Pituitary-Adrenocortical Axis Activity In Older Women
- 10. Study Shows Acute Dopamine Depletion Can Create Psychological Distress
- 11. Pharmacological and physiological aspects of sexual exhaustion in male rats
- 12. Subjective Experiences During Dopamine Depletion
- 14. Treatment-Seeking Inpatient Cocaine Abusers Show Hypothalamic Dysregulation of Both Basal Prolactin and Cortisol Secretion
- 15. Brain Activation during Human Male Ejaculation
- 16. Pharmacological and physiological aspects of sexual exhaustion in male rats
- 17. Anatomy of Love and Why We Love by Helen Fisher.
- 18. Dynamic changes in nucleus accumbens dopamine efflux during the Coolidge effect in male rats