status-seeking/social-dominance behavior.23 But the testosterone-fueled goal of getting to the top of the heap doesn't always lead to increased aggression; it could generate behaviors such as cooperating with others, if that helps men avoid rejection and, as a result, maintain their social standing.24
Testosterone is produced in the testicles of men, the ovaries of women, and in the adrenal glands of both sexes. In women, testosterone and other androgens can trigger responses similar to those of men, including increased muscle mass and social-dominance behaviors, and it is linked to sex drive. More is being learned about the role of androgens in women, but most scientific attention has been paid to estrogen and progesterone.
Estrogen: Estrogen, the primary female sex hormone, is produced by the ovaries and in small amounts by the liver, breasts, brain, and adrenal glands.25 It has profound effects on just about every part of women's bodies: heart, bones, blood vessels, skin, hair, breasts, mucous membranes, pelvic muscles, and urinary and reproductive tracts.26
In the brain, estrogen affects attention, motor control, pain reception, mood, and memory. In women, estrogen helps regulate the brain's ability to learn and encode memories; testosterone may perform the same function in men, although as mentioned earlier, testosterone makes estrogen.27
Women experience greater fluctuations of estrogen, which can affect women's moods, stress, and learning.28 Low estrogen may increase depression and compulsive behaviors. That's because estrogen regulates emotion in several ways, including:
Increasing serotonin and serotonin receptors, which regulate mood, sleep, and learning,
Modifying the production and effects of endorphins, the “feel-good” neurotransmitter,
Protecting nerves from damage and perhaps stimulating nerve growth.29
Progesterone: This hormone is involved in pregnancy, regulating everything from sex drive, ovulation, the uterine lining, maintenance of pregnancy, and lactation—in short, everything you’d want and need to have a baby.
Much of what we understand about progesterone's effects comes from what happens to our bodies when it's low: infertility, insomnia, sore breasts, weight gain, water retention, vaginal dryness, and decreased sex drive.30 Lowered levels can even cause migraine headaches, depression, panic attacks, abnormal menstrual cycles, and blood-sugar problems.31
Beyond its role as the pregnancy hormone, progesterone has neuro-protective properties and helps with traumatic brain injury by reducing swelling.32 It is positively associated with increased social connection as well.33
Other Hormones
Even the amounts of certain nonsexual hormones (people have over fifty hormones) are different in men and women. What's also different is how sensitive each sex is to them and the disorders each sex can experience because of them. Here's look at three of these hormones.
Oxytocin: When you fall in love, want to cuddle, or are a mom of a baby and want to nurse, oxytocin is at work. Oxytocin (not Oxycontin, the prescribed painkiller) has major roles in
Birth, lactation (releasing breast milk), and maternal bonding;
Managing the circadian rhythm—your internal twentyfour-hour clock that determines when you want to fall asleep and wake up;34
Trust and bonding via actions such as parenting, hugging, touching, and having orgasms—which is why it's called the “love hormone.”35
Because women can give birth, we have more oxytocin than men, and it works better for us. Oxytocin is amplified by estrogen and counteracted by testosterone, says Marianne J. Legato, MD, FACP, author of Why Men Never Remember and Women Never Forget and founder of Columbia's Partnership for Gender-Specific Medicine.36 That means that after sex, when you and your male partner both have a burst of loving oxytocin, you both want to cuddle and connect—at first. But testosterone counteracts the oxytocin, and the fact your sweetie might want to soon do something different, like check his e-mail, could have nothing to do with you.
Oxytocin has been used to induce labor, but more recently has been put into a nasal spray and marketed to helping with everything from autism and shyness to getting your man to share more in a relationship.37
Thyroid Hormone: The thyroid gland secretes a hormone that regulates metabolism, or how the body uses energy. Thyroid hormone affects a long list of items, including weight, body temperature, breathing, muscle strength, skin dryness, menstrual cycles, brain development, cholesterol levels, and heart and nervous-system functions. Just about every organ in your body can be affected by this one-ounce gland, shaped like a butterfly, that's located in the lower part of your neck.
Because of pregnancy, aging, and autoimmune disease, women's thyroids often get out of sync, sometimes producing too much thyroid hormone and, more often, too little. It can be hard to distinguish symptoms of thyroid problems from other concerns—such as depression, menopause, and fibromyalgia—and thyroid issues can make these concerns worse.
If you are hyperthyroid, with too much thyroid hormone, you may have some of these signs and symptoms:
Nervousness, anxiety, irritability, and/or panic disorder;
Increased perspiration and/or heat intolerance;
Racing heart and palpitations (irregular heartbeats);
Thinning skin and/or hair;
Muscular weakness, especially in the upper arms and thighs;
Shaky hands;
Staring gaze;
Insomnia and/or fatigue;
More frequent bowel movements;
Weight loss despite a good appetite;
Lighter menstrual flow and/or less frequent menstrual periods.
Hyperthyroidism and one of its causes, Graves' disease (an autoimmune thyroid illness38), affect eight times as many women than men. Treatment depends on the cause of the hyperthyroidism and ranges from no treatment to antithyroid medication to radioactive iodine.
If you are hypothyroid,
