When you're in the mood, it's a sure bet that the last thing on your mind is boosting your immune system or maintaining a healthy weight. Yet good sex offers those health benefits and more.

Sex does a body good in a number of ways, according to experts. The benefits aren't just anecdotal or hearsay -- each of these 10 health benefits of sex is backed by scientific scrutiny.

Among the benefits of healthy loving in a relationship:

1. Sex Relieves Stress
A big health benefit of sex is lower blood pressure and overall stress reduction, according to researchers from Scotland who reported their findings in the journal Biological Psychology. They studied 24 women and 22 men who kept records of their sexual activity. Then the researchers subjected them to stressful situations -- such as speaking in public and doing verbal arithmetic -- and noted their blood pressure response to stress.

Another study published in the same journal found that frequent intercourse was associated with lower diastolic blood pressure in cohabiting participants. Yet other research found a link between partner hugs and lower blood pressure in women.

2. Sex Boosts Immunity
Good sexual health may mean better physical health. Having sex once or twice a week has been linked with higher levels of an antibody called immunoglobulin A or IgA, which can protect you from getting colds and other infections. Scientists at Wilkes University in Wilkes-Barre, Pa., took samples of saliva, which contain IgA, from 112 college students who reported the frequency of sex they had.

Those in the "frequent" group -- once or twice a week -- had higher levels of IgA than those in the other three groups -- who reported being abstinent, having sex less than once a week, or having it very often, three or more times weekly.

3. Sex Burns Calories
Thirty minutes of sex burns 85 calories or more. It may not sound like much, but it adds up: 42 half-hour sessions will burn 3,570 calories, more than enough to lose a pound. Doubling up, you could drop that pound in 21 hour-long sessions.

4. Sex Improves Cardiovascular Health
While some older folks may worry that the efforts expended during sex could cause a stroke, that's not so, according to researchers from England. In a study published in the Journal of Epidemiology and Community Health, scientists found frequency of sex was not associated with stroke in the 914 men they followed for 20 years.

And the heart health benefits of sex don't end there. The researchers also found that having sex twice or more a week reduced the risk of fatal heart attack by half for the men, compared with those who had sex less than once a month.

5. Sex Boosts Self-Esteem
Boosting self-esteem was one of 237 reasons people have sex, collected by University of Texas researchers and published in the Archives of Sexual Behavior.

That finding makes sense to Gina Ogden, PhD, a sex therapist and marriage and family therapist in Cambridge, Mass., although she finds that those who already have self-esteem say they sometimes have sex to feel even better. "One of the reasons people say they have sex is to feel good about themselves," she tells WebMD. "Great sex begins with self-esteem, and it raises it. If the sex is loving, connected, and what you want, it raises it."

6. Sex Improves Intimacy
Having sex and orgasms increases levels of the hormone oxytocin, the so-called love hormone, which helps us bond and build trust. Researchers from the University of Pittsburgh and the University of North Carolina evaluated 59 premenopausal women before and after warm contact with their husbands and partners ending with hugs. They found that the more contact, the higher the oxytocin levels.

"Oxytocin allows us to feel the urge to nurture and to bond," Britton says.

Higher oxytocin has also been linked with a feeling of generosity. So if you're feeling suddenly more generous toward your partner than usual, credit the love hormone.

7. Sex Reduces Pain
As the hormone oxytocin surges, endorphins increase, and pain declines. So if your headache, arthritis pain, or PMS symptoms seem to improve after sex, you can thank those higher oxytocin levels.

In a study published in the Bulletin of Experimental Biology and Medicine, 48 volunteers who inhaled oxytocin vapor and then had their fingers pricked lowered their pain threshold by more than half.

8. Sex Reduces Prostate Cancer Risk
Frequent ejaculations, especially in 20-something men, may reduce the risk of prostate cancer later in life, Australian researchers reported in the British Journal of Urology International. When they followed men diagnosed with prostate cancer and those without, they found no association of prostate cancer with the number of sexual partners as the men reached their 30s, 40s, and 50s.

But they found men who had five or more ejaculations weekly while in their 20s reduced their risk of getting prostate cancer later by a third.

Another study, reported in the Journal of the American Medical Association, found that frequent ejaculations, 21 or more a month, were linked to lower prostate cancer risk in older men, as well, compared with less frequent ejaculations of four to seven monthly.

9. Sex Strengthens Pelvic Floor Muscles
For women, doing a few pelvic floor muscle exercises known as Kegels during sex offers a couple of benefits. You will enjoy more pleasure, and you'll also strengthen the area and help to minimize the risk of incontinence later in life.

To do a basic Kegel exercise, tighten the muscles of your pelvic floor, as if you're trying to stop the flow of urine. Count to three, then release.

10. Sex Helps You Sleep Better
The oxytocin released during orgasm also promotes sleep, according to research.

And getting enough sleep has been linked with a host of other good things, such as maintaining a healthy weight and blood pressure. Something to think about, especially if you've been wondering why your guy can be active one minute and snoring the next.

Why do we love roller coasters? They are almost a perversion of the pleasure-pain principle. We are drawn to them even as they incite fear, get our hearts racing, turn our knuckles white and toss us around mercilessly. Then we get off and jump right back in line. Beginning in the early 1990s, roller coasters began their second Golden Age (the first was during the Jazz-Age 1920s when the wooden lattices dotted the U.S. landscape) and their numbers and variety show no signs of letting up. Why do we love roller coasters? Who knows? But, it seems, we can't get enough of them.

1. Don’t stick out your tongue if you want to hide your identity. Similar to fingerprints, everyone also has a unique tongue print!

2. Your pet isn’t the only one in the house with a shedding problem. Humans shed about 600,000 particles of skin every hour. That works out to about 1.5 pounds each year, so the average person will lose around 105 pounds of skin by age 70.

3. An adult has fewer bones than a baby. We start off life with 350 bones, but because bones fuse together during growth, we end up with only 206 as adults.

4. Did you know that you get a new stomach lining every three to four days? If you didn’t, the strong acids your stomach uses to digest food would also digest your stomach.

5. Your nose is not as sensitive as a dog’s, but it can remember 50,000 different scents.

6. The small intestine is about four times as long as the average adult is tall. If it weren’t looped back and forth upon itself, its length of 18 to 23 feet wouldn’t fit into the abdominal cavity, making things rather messy.

7. This will really make your skin crawl: Every square inch of skin on the human body has about 32 million bacteria on it, but fortunately, the vast majority of them are harmless.

8. The source of smelly feet, like smelly armpits, is sweat. And people sweat buckets from their feet. A pair of feet have 500,000 sweat glands and can produce more than a pint of sweat a day.

9. The air from a human sneeze can travel at speeds of 100 miles per hour or more — another good reason to cover your nose and mouth when you sneeze — or duck when you hear one coming your way.

10. Blood has a long road to travel: Laid end to end, there are about 60,000 miles of blood vessels in the human body. And the hard-working heart pumps about 2,000 gallons of blood through those vessels every day.

11. You may not want to swim in your spit, but if you saved it all up, you could. In a lifetime, the average person produces about 25,000 quarts of saliva — enough to fill two swimming pools!

12. By 60 years of age, 60-percent of men and 40-percent of women will snore. But the sound of a snore can seem deafening. While snores average around 60 decibels, the noise level of normal speech, they can reach more than 80 decibels. Eighty decibels is as loud as the sound of a pneumatic drill breaking up concrete. Noise levels over 85 decibels are considered hazardous to the human ear.

13. Blondes may or may not have more fun, but they definitely have more hair. Hair color helps determine how dense the hair on your head is, and blondes (only natural ones, of course), top the list. The average human head has 100,000 hair follicles, each of which is capable of producing 20 individual hairs during a person’s lifetime. Blondes average 146,000 follicles. People with black hair tend to have about 110,000 follicles, while those with brown hair are right on target with 100,000 follicles. Redheads have the least dense hair, averaging about 86,000 follicles.

14. If you’re clipping your fingernails more often than your toenails, that’s only natural. The nails that get the most exposure and are used most frequently grow the fastest. Fingernails grow fastest on the hand that you write with and on the longest fingers. On average, nails grow about one-tenth of an inch each month.

15. No wonder babies have such a hard time holding up their heads: The human head is one-quarter of our total length at birth but only one-eighth of our total length by the time we reach adulthood.

16. If you say that you’re dying to get a good night’s sleep, you could mean that literally. You can go without eating for weeks without succumbing, but eleven days is tops for going without sleep. After eleven days, you’ll be asleep — forever!