"Libido Meter" May Be First True Sexual-Arousal Gauge

Stefan Lovgren
for National Geographic News
February 7, 2005
Israeli scientists have developed a test that can objectively determine the level of a person's sexual desire.

In the past, sex researchers have relied mostly on questionnaires and interviews to find out the extent of a person's sexual interest and attraction. The new test, on the other hand, records people's brain waves as the subjects are exposed to erotic video clips, with brain wave response indicating level of sexual interest.

The results may be useful to diagnose and treat sexual dysfunction or to measure the sexual side effects of drugs and injuries.

"The past work has been mostly devoted to looking at the physical correlates of sexual arousal and interest, such as changes in [genital] blood flow and effects on the heart rate and blood pressure," said Yoram Vardi, the head of the neuro-urology unit at the Rambam Medical Center and the Technion faculty of medicine in Haifa, Israel.

"It may now be a cliché, but it is no less true—the most important sexual organ is the brain," he said.

Vardi hopes the test will enable medical professionals to determine the root cause of diminished sexual desire, and whether medication or treatment is most effective to treat a problem. The test may also be useful in determining the effects of drugs that raise or lower libido.

The research team has informally called their test the "libido meter." So far, only people without sexual dysfunctions have been tested. Tests still need to be made with people suffering from dysfunctions.

A Measure of Health

Keeping track of sexual desire may be a more serious health issue than many people realize. Sex contributes to the overall physical and mental health of a person, researchers say.

"I think having frequent, satisfying sex keeps the hormone levels up and keeps us young, both physically and mentally," said Barbara Bartlik, a psychiatry professor at Weill Medical College of Cornell University in New York State.

In describing how sex helps, scientists are looking at three neurotransmitters released in the brain during sex:

Oxytocin promotes emotional bonding. "It is probably oxytocin that helps to explain the benefits of sexual experience," said Sue Carter, a researcher at the University of Illinois at Chicago. "This hormone influences the parasympathetic nervous system, which regulates and can reduce heart rate and blood pressure."

Endorphins provide natural relief from the pain of arthritis, injury, and even migraines. Endorphins also boost the immune system by dampening the harmful hormones that stress stimulates.

Serotonin contributes to the feeling of pleasure, satiety, and relaxation that people usually experience after good sex.

"Take all of that together, and its easy to see how pervasive sexual pleasure is to our well-being," said Jim Pfaus, a behavioral neuroscientist at Concordia University in Montreal, Canada.

Reducing Heart Disease

Regular sex also means regular exercise. It has been suggested that the average person burns about 200 calories while having sex. In men, sex boosts the production of testosterone, which leads to stronger bones and muscles.

Scientists also say that sex improves cholesterol levels, increases circulation, and combats heart disease. According to a 2001 study at Queens University in Belfast, Northern Ireland, men who had sex three or more times per week reduced their risk of heart attack by half.

Self Esteem

There is a strong link between sex and a person's psychological well-being. Researchers know, for example, that sexual dysfunction can easily lead to depression.

"I know from my work with patients who have sexual dysfunction that a sexual problem can become all consuming," Bartlik said. "The person with a sexual problem often can think of nothing else."

That sort of obsession often affects a persons self-esteem and causes a general increase in life stress.

But people who are able to overcome sexual dysfunction may experience a rush of good feeling that can lift them out of depression. A study on men with erectile disorder and depression showed that sildenafil (in drugs like Viagra) improved not only their erections, but also their depression.

"A good sexual relationship can have a profoundly positive impact on a person's mental health," Bartlik said. "When people feel good about their sex life, they are more confident about themselves and have happier moods. They can even have higher levels of sex hormones."

Pfaus, the neuroscientist, said that sexual pleasure also helps give meaning and purpose to our lives.

"The thing to remember is that sex is probably at the top of the hierarchy of natural pleasures," he said. "It is the state of satisfaction created by enjoying it that buffers you from stress."

Don't Miss a Discovery
Sign up our free newsletter. Every two weeks we'll send you our top news by e-mail (see sample).

© 1996-2008 National Geographic Society. All rights reserved.