Also known as sex drive, it’s a person’s overall sexual desire for sexual activity. The libido is governed primarily by activity in the mesolimbic dopamine pathway. As a consequence, dopamine and related trace amines that modulate dopamine neurotransmission play a critical role in regulating libido.
A woman’s desire for sex is correlated to her menstrual cycle. This cycle has been associated with changes in a woman’s testosterone levels. These levels have a direct impact on a woman’s interest in sex, with many women experiencing a heightened sexual desire in the several days immediately before ovulation. In the week following ovulation, on the other hand, the testosterone level is the lowest and as a result women experience less sex interest.
There is no widely accepted measure of what is a healthy level for sex desire. Some people want to have sex every day, or more than once a day; others once a year or not at all. However, a person who lacks a desire for sexual activity for some period of time may be experiencing a hypoactive sexual desire disorder or may be asexual.
Males reach the peak of their sex drive in their teens, while females reach it in their thirties. The surge in testosterone hits the male at puberty resulting in a sudden and extreme sex drive which reaches its peak at age 15–16, then drops slowly over his lifetime. In contrast, a female’s libido increases slowly during adolescence and peaks in her mid-thirties. Actual testosterone and estrogen levels that affect a person’s sex drive vary considerably.
At menopause the levels of estrogen decrease and this usually causes a lower interest in sex and vaginal dryness which makes intercourse painful. However, the levels of testosterone increase at menopause and this may be why some women may experience a contrary effect of an increased libido. Sexual desire disorders are more common in women than in men, however, men can also experience a decrease in their libido as they age.
Certain psychological or social factors can reduce the desire for sex. These factors can include lack of privacy, stress, distraction or depression. Environmental stress, such as prolonged exposure to elevated sound levels or bright light, can also affect libido. Other causes include experience of sexual abuse, assault, trauma or neglect, body image issues and anxiety about engaging in sexual activity.