Libido; Everything You Wanted To Know!

Libido, also referred to as sex drive, is a person's overall desire for sexual activity. Libido is often an important factor in the formation and maintenance of relationships, and a libido mismatch between partners can affect relationships negatively.

Why Do We Have A Sex Drive?

Libido is recognised as an important force in the Darwinian theory of natural selection. Libido’s evolutionary purpose is to get the species to procreate, therefore passing genetic material to the next generation. From an evolutionary perspective, any mechanism that can increase the frequency of sexual intercourse during fertile days of a woman’s menstrual cycle, has a selective advantage by improving the chance of conception. And that’s why women have highly fluctuating sex drives, with a high urge to engage sexually just before ovulation in each menstrual cycle. Men’s sex drives remain relatively stable.

Neurobiology Of Libido

Libido is governed primarily by activity in the mesolimbic dopamine pathway. So what is the mesolimbic pathway? The mesolimbic pathway is also referred to as the reward pathway. The pathway connects an area called the ventral tegmental area in the midbrain to another area called the ventral striatum of the basal ganglia in the forebrain. The ventral striatum includes the nucleus accumbens and the olfactory tubercle.

For simplicity, just understand this: the release of neurochemicals through this pathway gives us pleasure, and that facilitates reinforcement; that is, any activity that gives us pleasure makes us want to keep doing it again and again. The same pathway is also involved in addiction to substances or behaviours. In this pathway, dopamine and related trace amines (primarily phenethylamine) that modulate dopamine neurotransmission play a critical role in regulating libido. Other neurotransmitters, neuropeptides, and sex hormones that affect sex drive by acting on this pathway include:

  • Testosterone (directly correlated)

  • Estrogen (directly correlated)

  • Oxytocin (directly correlated)

  • Progesterone (inversely correlated)

  • Serotonin (inversely correlated)

  • Norepinephrine (inversely correlated)

However, keep in mind that all of them affect sex drive to varying degrees; with Dopamine and Testosterone being the strongest modulators.

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Effects Of Age

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.

Sex Hormone Levels And The Menstrual Cycle

Testosterone levels rise gradually from about the 24th day of a woman's menstrual cycle until ovulation on about the 14th day of the next cycle, and during this period the woman's desire for sex increases consistently. The 13th day is generally the day with the highest testosterone and oestrogen levels. In the week following ovulation, the oestrogen and testosterone levels are the lowest and as a result women will experience less interest in sex. Also, during the week following ovulation, progesterone levels increase, resulting in a woman experiencing difficulty achieving orgasm.

Libido During Pregnancy And Lactation

In the first trimester of pregnancy, estrogen and progesterone levels rise. Symptoms in early pregnancy that may lower sexual desire include:

  • hormonal changes

  • exhaustion

  • queasiness

  • breast sensitivity

Around week 10, these increased hormone levels will drop off. At that point, fatigue and nausea decrease significantly. With the loss of those two symptoms may come an increase in sex drive, which peaks in late 1st trimester, and early 2nd trimester. Later in the third trimester, weight gain, back pain, and other symptoms again decrease sexual drive.

Also, during pregnancy and breastfeeding, prolactin levels increase, stimulating the breasts to produce milk. High prolactin levels push down estrogen levels, which in turn dampens sexual desire. Plus, levels of testosterone are also lower in breastfeeding women.

Libido Men Vs. Women

Although not an absolute rule, the following are general patterns derived from surveys and studies that make men and women different when it comes to libido:

1. Men Think More About Sex

The majority of men under 60 think about sex at least once a day, with an average of 15-20 times/day. For women, the number is half that. As men and women age, both fantasise less, but men still fantasise about twice as often. Men have more spontaneous sexual arousal and more frequent and varied fantasies

2. Men Seek Sex More

Men want sex more often than women at the start of a relationship, in the middle of it, and after many years of it. This isn't just true for heterosexuals; gay men also have sex more often than lesbians at all stages of their relationships. Men also want more sex partners in their lifetime, and are more interested in casual sex.

3. Men Masturbate More

According to multiple studies, about two-thirds of men say they masturbate, even though about half also say they feel guilty about it. By contrast, about 40% of women say they masturbate, and the frequency of masturbation is lesser among women. One study found that 58 percent of men entertained sexual fantasies during masturbation, while the figure for women was only 12 percent. Male fantasies contained more actual sex, whereas women’s fantasies were more likely than men’s to feature affection and bonding.

4. Men Take More Risks

Various surveys show men are more likely to seek sex even when it's frowned upon or outlawed. This is probably why prostitution is still mostly a phenomenon of men seeking sex with women, rather than the other way around.

5. Women's Sexual Turn-ons Are More Complicated Than Men's

Straight men are more turned on by depictions of male-female sex and female-female sex. Gay men are turned on by male-male sex. For women, things are a little more complicated. Women show about the same genital reaction to male-female, male-male, and female-female sex. That’s because men are very rigid and specific about who they become aroused by, who they want to have sex with, and who they fall in love with. In contrast, women may be more open to same-sex relationships thanks to their less-directed sex drives. Women probably have the capacity to become sexually interested in and fall in love with their own sex more than men do.

6. Women's Sex Drives Are More Influenced By Social And Cultural Factors

Women's sexual attitudes, desires, and practices are more influenced by their environment than men’s.

This means that:

  • Women's attitudes towards, and willingness to perform various sexual acts are more likely than men's to change over time.

  • Women are more influenced by the attitudes of their peer group in their decisions about sex.

  • Women with higher education levels are more likely to have performed a wider variety of sexual practices (such as oral sex); education makes less of a difference with men.

7. Women Take A Less Direct Route To Sexual Satisfaction