Dopamine. It's at the core of our sexual drives and survival needs, and it motivates us to do just about everything. This mechanism within the reward circuitry of the primitive brain has been around for millions of years and has changed very little. Rats, humans - indeed, all mammals - are very similar in this respect.
Dopamine is behind a lot of the desire we associate with eating, libido and sexual intercourse. Similarly, all addictive drugs trigger dopamine (the "craving neurochemical") to stimulate the pleasure/reward circuitry. So do gambling, shopping, overeating and other, seemingly unrelated, activities. Go shopping: dopamine. Smoke a cigarette: dopamine. Computer games: dopamine. Heroin: dopamine. Orgasm: dopamine. They all work somewhat differently on the brain, but all raise your dopamine in key reward circuitry structures. You get a bigger blast of dopamine eating high-calorie, high-fat foods than eating low-calorie vegetables. You may believe that you love ice cream, but you really love your blast of dopamine. You're genetically programmed to seek out high-calorie foods over others.
Similarly, dopamine drives you to have sex over most other activities. With dopamine as the driving force, biology has designed you to engage in fertilization behavior to make more babies, and urges you to move on to new partners to create greater genetic variety among your offspring. Your primitive brain accomplishes these goals of more progeny and promiscuity by manipulating your brain chemistry, and thus your desires and thoughts. High levels of dopamine increase sexual desire, encouraging you to behave recklessly. The thrill of a new affair and the rush from using Internet pornography are examples of high dopamine.
Unfortunately, consistently high levels of dopamine lead to erratic behavior and compulsions that are not conducive to survival. (See the "EXCESS" column in the chart below.) Most mammals, therefore, evolved with defined estrus periods when they "go into heat." The rest of the time they are more or less neutral about sex.
Humans, however, don't have a period of "heat" followed by a long period of indifference to sex. Unlike all other mammals, we have the potential for on-going, dopamine-driven sexual desire. Yet we, too, self-regulate. An "off switch" kicks in after too much passion. Two events happen simultaneously (in addition to many others, not yet well understood). Dopamine plummets and prolactin soars. In humans, it's not known how long prolactin stays elevated after orgasm, thus inhibiting dopamine. If rats are any indication prolactin may surge a few times a day creating a yo-yo cycle for some indefinite period (two weeks in rats).
Dopamine is "go get it!" and prolactin is "whoa!" This mechanism shifts your attention elsewhere: to hunting and gathering, taking care of babies, building shelters, and so forth. Without this natural, protective shutdown, you would pursue sex to the exclusion of all other activities. When rats were wired so that they could push a lever in their cages to stimulate the nerve cells on which dopamine acts, they just kept hitting the lever until they dropped - not even pausing to eat, nurse offspring or investigate potential mates.
Dopamine fosters cravings; the rise in prolactin puts the brakes on. Neurochemical events like these (drop in dopamine and rise in prolactin) are at the root cause of perception shifts that so often follows in the days or weeks after a passionate encounter. For more on the neurochemstry of sexual satiety see Women: Does Orgasm Give You a Hangover? and Men: Does Frequent Ejaculation Cause a Hangover?
Feelings & behaviors associated with dopamine levels (or altered sensitivity to dopamine)
|Compulsions||Depression||Feelings of well-being, satisfaction|
|Mania||Anhedonia—no pleasure, world looks colorless||Pleasure, reward in accomplishing tasks|
|Sexual fetishes||Lack of ambition and drive||Healthy libido|
|Sexual addiction||Inability to bond||Good feelings toward others|
|Unhealthy risk-taking||Low libido||Motivated|
|Aggression||Erectile dysfunction||Healthy risk taking|
|Psychosis||Social anxiety disorder||Sound choices|
|Schizophrenia||ADHD or ADD||Realistic expectations|
|Sleep disturbances, "restless legs"||Parent/child bonding|
|Contentment with "little" things|
As you can see from this chart, a balanced level of dopamine is necessary for good mental health. When dopamine drops, you can feel like something is dreadfully wrong. Too much dopamine also leads to reckless behavior and restless anxiety, which can be quite severe. Either way, these uncomfortable feelings are often then projected onto your partner. Bingo! Suddenly, he or she doesn't look so appealing.
This is a very uncomfortable cycle to experience in your intimate relationship. During the "hangover," or "low-dopamine" portion of the cycle, you may feel abandoned, or as if someone is demanding things from you in ways that you cannot tolerate. Or you may desperately seek new highs (alcohol, sweets, new partners, pornography, and so forth) to raise your dopamine levels again. 1 Perhaps you can see how this cycle of highs and lows, or attraction and repulsion, can make your relationship feel more like a roller-coaster ride than a romantic fairytale. It is like starting and stopping in heavy traffic. It shows up in lovers' lives as intense attraction, followed by behaviors that tend to separate them. (Prolactin can promote separation, too, as we'll see in a moment.) The point is that conventional sex can play havoc with your neurochemistry. Much of the time, your dopamine levels will be uncomfortably high or uncomfortably low. This is why the ancient Chinese Daoists and other sages throughout history have recommended making love without conventional orgasm. By avoiding the extreme highs that over-stimulate the nerve cells in the primitive brain, you also avoid the temporary lows that accompany recovery. You help keep your dopamine levels within ideal ranges. This produces a sense of wellbeing, which promotes harmony in your relationship.
Dopamine is not the only culprit that contributes to the behaviors and mood swings that separate intimate partners emotionally. Prolactin, the neurochemical that shoots up after orgasm, is associated with many of the very symptoms that long-term couples complain of in their relationships. After mating, female rats show twice-daily surges in prolactin for up to two weeks - even if they don't get pregnant, and evidence of a similar post-coital prolactin surge in women is now showing up.
Finally, prolactin is associated with the stress of feeling hopeless. As partners grow distressed and discouraged by the puzzling highs and lows in their relationships, their higher prolactin levels can compound their distress. They forget what it feels like to be in balance, and gradually lose their natural sense of wellbeing. It's possible that surges of prolactin inhibit dopamine - and increase your craving for better sex or new partners who would raise your dopamine levels.
|Loss of libido||Loss of libido|
|Mood changes / depression||Mood changes / depression|
|Menopausal symptoms, even when estrogen is sufficient||Infertility|
|Signs of increased testosterone levels||Decreased testosterone levels|
|Weight gain||Weight gain|
|Intercourse may become painful because of vaginal dryness||Peripheral vision problems|
|Infertility, irregular menstruation||Gynecomastia (growing breasts)|
There are at least three sources of emotional friction related to these brain chemistry shifts:
(1) Partners get out of sync. Dopamine levels rise in one while the prolactin levels are still high in the other. You may desperately want sex, while your partner has no interest at all.
(2) Partners project their state of mind onto each other. When you feel rotten, or "hungry," or just plain "off," it's normal to find fault with the person closest to you. It honestly seems like you'd feel fine if he'd just be more generous, or she would just stop shopping for more and more shoes and make love.
(3) Partners' brains get rewired over time, away from love and toward defensiveness. The part of your primitive brain that is designed to react to snakes and predators is now being activated by your partner. Certainly your partner didn't threaten to poison you, but sex with your partner later made you feel bad at a subconscious (neurochemical) level.
Actually, of course, your partner is innocent. You hurt yourself by letting biology tell you how to have a good time in the bedroom. Your subconscious, however, feels that your lover is the culprit.
Virtually no one identifies this hidden, biological source of distress. Instead, the part of your brain that analyzes looks for other explanations. You know, for example, that you don't feel right. Your partner is acting weird. You're upset, and your honeymoon has ended. Maybe you write off your uneasiness as a mood swing, or get a prescription for an antidepressant. Or maybe you feel that your partner is somehow to blame for the fact that you feel rotten.
"If only he would help more around the house." "If only she would stop badgering me." And so on. Yet, when you try to fix each other, you're addressing symptoms and ignoring the deeper problem - these neurochemical shifts. To heal the underlying problem, you may just have to change the way you make love.