The Economist has declared that sleep is the new sex. But don’t ditch your lace undies for cozy flannels yet. Just as a good night’s sleep will do wonders for your mood, a joyful jump in the hay will keep you fit and stress-free. And even if you occasionally pull a Meg Ryan and fake it, you’ll still reap the rewards. “Sexual activity releases sex hormones that have beneficial effects on our immune, cardiovascular and neurological systems,” says Dr. Ted Jablonski, a clinical associate at the Sexual Health Clinic in Calgary. Here are five reasons why you should do it.

Sexercise Forget Bikram yoga class; a little sweaty sexercise might be an easier way to get your cardio and strength training. Researchers at The University of Sheffield in the United Kingdom studied 70 couples and found that those who had regular sex were in better physical shape than those whose lovemaking sessions were more sporadic. Not surprising, says Dr. Cedric Bryant, chief science officer for the American Council on Exercise. “You get some cardio benefits from having sex,” he says. “It raises your heart rate and burns 150 to 200 calories an hour — that’s equivalent to a brisk walk.” (Even if you’re not rounding home right away, kissing alone uses 29 muscles and torches 20 calories per minute, according to research by Beiersdorf AG, the makers of NIVEA Lip Care.) Sex can also build muscle. “Depending on your position, it can add muscular training and conditioning as well as core stability from maintaining positions,” says Bryant.

Happy hour The next time you’re feeling gloomy, skip the Ben & Jerry’s — some X-rated canoodling could be a better way to beat the blahs. Researchers at Arizona State University asked 58 women to record their moods and levels of sexual activity and physical affection over 36 weeks. Those women who experienced both affection and sex reported being in a better mood the next day. Chalk it up to endorphins — neurotransmitters that are released during sexual activity, says Jablonski. “Endorphins are produced in the brain and make you feel happy — almost giddy,” he says. “This is what causes that classic ‘afterglow’ phenomenon.”

First aid Marvin Gaye was onto something when he called it “sexual healing.” During intercourse, two chemicals are released in the body: endorphins and oxytocin; together, they act as a powerful opiate. (A study at the University of Vienna found that women’s oxytocin levels increase significantly as quickly as one minute after an orgasm.) So, if you have a headache, the horizontal mambo could be just what the doctor ordered. “Studies have shown that sex increases your pain threshold for [ailments such as] migraines and even menstrual cramps,” says Dr. Hilda Hutcherson, a gynecologist and professor of obstetrics and gynecology at Columbia University Medical Center in New York.

Stay young with sex on the next page …

How well do you handle stress?
Big chill We all know that stress is bad for us; luckily, we can have fun getting rid of its unhealthy side effects. Stuart Brody, a professor at the University of Paisley in Scotland, found that having sex can help lower your blood pressure when you’re reacting to stressful situations. In a 2006 study that examined 24 women and 22 men, those who had penile-vaginal intercourse had better stress responses than those who abstained or participated in other sexual activities, such as masturbation. Again, it’s because of oxytocin, says Lisa Martinez, executive director of The Women’s Sexual Health Foundation in Ohio. “The hormone creates a sense of well-being and happiness,” adds Hutcherson.

Forever young Sure, a visit to the dermatologist’s office might help eradicate a wrinkle or two. But hitting it with your partner could give you even greater anti-aging benefits. A study of 3,500 people at the Royal Edinburgh Hospital in Scotland found that couples who had sex at least three times a week looked at least 10 years younger than those who had sex twice a week. Regular sex can boost your immune system too: a 2004 study at Wilkes University in Pennsylvania found that those who had sex once or twice a week had higher levels of immunoglobulin A — an antibody that plays a critical role in the immune system — than those who had sex less often.

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