Let's Talk About Sex: Under 40

The "under 40" age bracket is pretty huge. A lot happens during those years: changes to your body, your brain and, of course, your ability to have sex.

"When it comes to sex, there is no normal," said Carol Queen, Ph.D., Good Vibrations staff sexologist and author of "The Sex & Pleasure Book: Good Vibrations Guide to Great Sex for Everyone." She explained that everything we discuss about sex is just the gist at various times in a life span, not the whole portrait; people age differently and have all kinds of ideas regarding their sexual desires and practices.

Of course, we know physical and mental aspects such as sex drive, hormones, life pressures and proneness to certain conditions evolve over time. But we'll try to take a snapshot of what changes to expect at different ages. We begin our journey by taking a look at sex under 40 years old.

In general, Queen said this period of life—late teens through the 30s—is often considered a person's sexual prime.

"It's a time during the life span marked by coming to understand yourself sexually," she said. "Unless that doesn't happen until later, it's a time to learn about sex and how to have it, although there is a wide range of possibilities that most people do not fully explore."

Research from the Kinsey Institute shows this is the age group that has the most sex. People younger than 30 typically have sex twice a week, and this rate declines to 1.6 times a week between ages 30 and 39.

The decline in frequency in our 30s makes sense. This tends to be the age when people are reaching greater heights in their career, committing to having a family, having more day-to-day stresses and, in general, undergoing more mental strain.

"Partnering and sometimes cohabitating and/or having kids can cause significant impacts in partners' sexual relationships, but many don't know this until it happens to them," Queen explained.

Typically, men younger than 40 are considered to be in their sexual prime, said Justin Houman, M.D., reproductive urologist and men's health specialist at Tower Urology in Los Angeles.

"The majority of men [in this group] have strong erections, and testosterone and energy levels are typically great," Houman noted, adding that the younger you are, the longer you can typically last during sex.

Houman said men in this age group, however, tend to have a little more anxiety regarding sexual performance.

"If guys are experiencing sexual dysfunction at a young age, a large majority of these men—not all—find that there is a psychological component to it, which we'll call psychogenic erectile dysfunction," Houman said, explaining that psychogenic ED is less common in older men.

Michael Werner, M.D., medical director and founder of Maze Sexual & Reproductive Health, based in New York City and Purchase, New York, pointed out, however, that 10 percent of erectile dysfunction in younger men is due to physical causes.

"So if you are having erectile dysfunction problems at a young age, make sure you see a urologist to find the root cause," Werner said. "Even though a physical cause of erectile dysfunction is less common, it shouldn't be discounted."

Werner said although we usually think of sexual problems occurring in older men, they are actually very common and underestimated in men younger than 35.

"The most common sexual dysfunction for men overall is premature ejaculation, which is thought to affect up to 30 percent of men," Werner said, explaining there are various definitions of premature ejaculation, but the classic definition is ejaculating within one minute of penetration.

"However, I really don't feel that this is a helpful definition," Werner noted. "If a man is spending the whole time once penetrated trying not to ejaculate and it gets in the way of his and his partner's enjoyment, then I consider this premature ejaculation."

Werner said premature ejaculation is prevalent and not a psychological issue. But it is a lifelong condition that begins once a man becomes consistently sexually active. Therefore, although it affects men of all age groups, it is initially noticed when a man is younger and starts having sex.

"Although we can't cure it, we can always help a man manage it and last longer," Werner said. "We can either help a man to delay his ejaculation or get him to keep his erection after ejaculation."

Werner said many men struggle with premature ejaculation and don't seek help until they are with a long-term partner later in life. However, it doesn't need to be that way. If you are experiencing problems with premature ejaculation, don't hesitate to seek advice from a specialist in sexual dysfunction.

Like men, young women have a high sex drive with hormones in abundance, said Linda Burkett, M.D., a physician in the department of obstetrics and gynecology at Virginia Commonwealth University Health, specializing in pelvic health and urogynecology.

"Although, interestingly, there is research to show that women in their 20s have less frequent sex than women in their 30s," Burkett said. "Women also tend to have sex earlier in relationships once they reach their 30s."

Burkett hypothesized this tendency is because women become more comfortable with themselves, having sex and assessing relationships.

Young women also generally have a greater understanding of protecting themselves against sexually transmitted diseases (STDs).

"However, this is often overlooked when reaching the late 30s or 40s, especially if coming out of a long-term relationship," Burkett said.

Therefore, it's essential to remember that STDs can happen at any age and take appropriate precautions, such as regular screening and condom use.

Burkett said there are two points in the under-40 age group when she tends to see women more frequently for sexual concerns. The first is when they become more aware of their fertility and try to have a family. The second is after childbirth.

Research indicates the stresses of trying to get pregnant can affect libido and reduce sexual desire. Indeed, infertility has a whole-life impact. Both partners are dealing with feelings of loss, grief, exhaustion and stress, all of which can cause a disconnection in the relationship, affecting the regularity of sex.

"Then if a woman is lucky enough to get pregnant and carry a baby to term, after having a pregnancy, a lot changes to the pelvic floor," Burkett noted. "It typically takes about a year to fully heal and get back to your usual level of function and sexual drive."

Postpartum and breastfeeding women can see a tremendous decrease in libido, as well as experience pain during sex and other issues, especially if the birth was traumatic.

"There are a lot of treatments to help with pelvic floor concerns postpartum," Burkett said, adding that sex during pregnancy and postpartum life are very different. "It takes some time for healing to take place and for women to find where their new normal is."

Queen added that postpartum sexual changes can involve sleep disruption. The Sleep Foundation states that sleep deprivation is associated with reduced sexual desire in women. Furthermore, fatigue can hinder sexual activity, and poor sleep can lead to mental health problems such as depression or anxiety, emotional difficulties and relationship problems.

Burkett highlighted that although the fatigue and stressors of having young children can alter your sex life, they can strengthen your relationship. The new normal of sex you find after starting a family is not necessarily worse. It can, in fact, be a whole lot better.