Hormones are a class of signaling molecules that exist in all multi-cell organisms and, in humans, include commonly-known examples like melatonin, testosterone , and cortisol. They influence the health and functioning of the body and brain in a wide variety of ways; on a psychological level, they affect mood, how we behave, who we’re attracted to (or not), and more.
Hormones and Everyday Life
Hormones are silent drivers of behavior and personality , and their molecular fingerprints are on countless day-to-day activities and occurrences, ranging from attraction to appetite. Decades of biological and psychological research have found that certain hormones are associated with specific traits, emotions, and behaviors, but in reality, the human endocrine system is so complex that the same chemical may behave radically differently from person to person. Hormones affect people in different ways throughout their lives, and hormone levels can spike dramatically at physical or emotional transitions. New parents are slammed with a rush of hormones, for instance, as are rookie players on sports teams and tweens entering middle school.
Hormones affect behavior in myriad, complex ways that are often dependent on the situation. Testosterone, for example, has been linked to aggressive or antisocial behavior and competitiveness in situations that call for it. On the other hand, in non-competitive situations, testosterone has been associated with protectiveness , generosity , and prosocial behavior.
Hormones have a hand in aggression, dominance, risk-aversion, warmth, generosity, and other elements that determine how someone behaves, thinks, and feels. Hormones’ connection to personality models such as the Big 5 is less clear, though some studies have found, for instance, that higher levels of testosterone and dopamine are both linked to greater extraversion .
Surges in hormones like oxytocin and dopamine can drive feelings of happiness , contentment, or excitement, while drops in hormones like estrogen and progesterone may trigger negatively charged mood swings. Dips in testosterone may correlate with low mood; excessive testosterone may trigger rage or aggression.
Men, Women, and Sex Hormones
When laypeople think of hormones, the sex hormones—most notably testosterone and estrogen—are often the first ones that come to mind, for unsurprising reasons. The sex hormones are critical for sexual function, libido, and reproduction—areas of great interest to many adults—and they also have a hand in romantic bonds and long-term relationships. Despite their renown, however, the sex hormones are more complex than is widely understood. And while they certainly influence sexual behavior, they are not the sole driver of an individual’s sexual and romantic satisfaction.
Past studies have found that during ovulation (when levels of hormones like estrogen increase), heterosexual women are more attracted to men with “masculine” faces (strong jaw, heavy brow, etc). However, newer and more rigorously-designed research finds little correlation between ovulation and women’s mate preferences, suggesting that the role of hormones in women’s sexual taste may be overstated.
Research has found that heterosexual women do appear to be more interested in sex during ovulation —both with a long-term partner and with men outside of the pair. The evolutionary reasons for this make sense, as desiring sex during the fertile period of ovulation would make them more likely to conceive.
Testosterone may increase heterosexual men’s preference for women with more feminine faces, research finds—at least for short-term relationships. Some evidence suggests that men with increased levels of testosterone are less attracted to feminine women for long-term relationships—perhaps, the researchers suggest, because women with more feminine facial features have been found in past studies to be perceived as more promiscuous.
When Hormones Go Awry
Since hormones serve such a wide range of functions in the mind and body, they can trigger unpleasant physical or psychological symptoms—or even medical conditions—when they fall out of balance. Hormonal imbalances or endocrine disorders are not always easy to identify, and may require medical tests to properly diagnose. But while endocrine disorders may necessitate formal medical treatment, certain hormonal imbalances may be treated with lifestyle changes or by addressing symptoms directly. In some cases, however, supplemental hormones may be given to correct imbalances.
Ultimately, hormones—even the same hormone—can serve a wide range of functions, from slowing growth to stimulating it, and from activating the immune system to inhibiting it. There is little in the human body that hormones don't play a role in; as a result, when hormone levels are thrown off balance, the effects can appear in a variety of ways.
A hormonal imbalance is said to occur when there is too much or too little of a particular hormone in the bloodstream. It may trigger negative physical or psychological symptoms, such as mood instability or depression , weight gain or weight loss, disrupted menstrual cycles, frequent fatigue, muscle pain, or a wide range of other symptoms.
Individuals who suspect a hormonal imbalance should consult with a medical professional to measure hormone levels and test for other possible causes of negative symptoms. If a hormonal imbalance is identified, treatment may include hormonal supplement therapy or hormonal-blocking medications (such as anti-androgen medications). Lifestyle changes, such as losing weight or eating a healthier diet, may also help the body better regulate its hormones.
Hormone Myths and Facts
Testosterone is what makes men so manly. Oxytocin is the “love hormone.” And cortisol is responsible for crazy amounts of stress, right?
Not exactly. In fact, most of what the average person understands about the role of hormones is a heavily simplified version of how they actually function in the human body. In reality, testosterone is necessary for both males and females. Oxytocin can stimulate pleasant feelings and boost close bonds, but it has also been linked to feelings of social prejudice . And cortisol helps the body deal with stressful situations; it’s only when there’s too much of it present for too long that it starts to have negative effects.
Oxytocin is produced in the brain during sex, childbirth, breastfeeding, and other activities that promote close bonds between romantic partners, parents and children, or tight social groups—hence it’s reputation as a “love hormone.” But it can also foster negative behavior. In human and animal studies, stimulating oxytocin receptors in the brain was shown to trigger aggression , an “us-versus-them” mentality, social avoidance, or dishonesty—all directed toward out-group members. Such behavior is likely to prioritize the well-being of the “in-group,” thus further fostering a family or tribe’s social bonds.
Yes. Despite testosterone’s better-known association with male behavior and development, testosterone is actually important for both sexes—particularly when it comes to sexuality . Studies show that women with diminished testosterone (produced in the ovaries and the adrenal gland) show markedly decreased libido; in some cases, treating such women with testosterone may help overcome a low sex drive.
Explore More About Hormones
For a comprehensive understanding of hormones, read our complete guide: