Is sex good for your health—or is that just a fantasy?
A flurry of small studies suggest that sex is as good for your health as vitamin D and broccoli. It not only relieves stress, improves sleep and burns calories, it can also reduce pain, ease depression, strengthen blood vessels, boost the immune system and lower the risk of prostate and breast cancer.
Ray Bartkus缓解压力：迅速上升的激素水平提振情绪，促进亲近感，帮助控制数天的压力。Ray Bartkus体重：性行为能够每分钟燃烧掉5卡路里热量，这表示在大约12小时内即可减掉一磅。Ray Bartkus心脏健康：性行为能够使心率提高到相当于爬两段楼梯的水平。Ray Bartkus改善睡眠：劳累过后，催产素和催乳素带来饱食感和睡意－－尤其是对于男性而言。Ray Bartkus延年益寿：更多的性行为对男性意味着寿命更长；女性获得性满足能长寿。然而这些研究中有许多都有赖于被研究者回忆并坦诚地讲述他们的性行为，而很多人无法区分因果，也就是说，究竟是性爱让人们变得更健康还是更健康的人会有更多的“嘿咻”行为？
But many of those studies rely on people to remember and report their sexual activity honestly and many can't distinguish between cause and effect. That is, does sex make people healthier or do healthier people have more sex?
要评估这些论断还需要进行更多的研究。《性医学杂志》(Journal of Sexual Medicine)的主编、加州圣地牙哥阿尔瓦拉多医院(Alvarado Hospital)性医学部门主任、泌尿科医生戈尔茨坦(Irwin Goldstein)说，如果我跟你说我们已经对这些问题进行了随机双盲对照多中心试验，这是在骗人。他说，最大的阻碍在于研究资金的缺乏，如果在你的基金申请计划书中出现了“性爱”一词，它就很难获得批准了。
More research is needed to evaluate all these claims. 'If I told you we have randomized double-blind placebo-controlled multi-center trials on these questions, there is no such a thing,' says Irwin Goldstein, a urologist and editor in chief of the Journal of Sexual Medicine. The biggest obstacle is lack of funding, he says. 'If 'sex' is in your grant proposal, it's very hard to get it approved.'
Still, a look at what researchers do know about the physiology of sex shows that at least a few health benefits may come along with that roll in the hay.
Some benefits of sex—beyond producing a baby, that is—are obvious even without scientific evidence. 'When you have good sex, there's a relaxation response and a satiation response…you lie there and life is great,' says Dr. Goldstein, who is also the director of sexual medicine at Alvarado Hospital in San Diego, Calif.
这种感觉在很大程度上是由于身体内的化学反应造成的——“嘿咻”过程中会有大量荷尔蒙和神经递质迅速增加和减少。这种“觉醒”刺激了多巴胺的分泌，而多巴胺又启动了大脑的渴求中枢和奖赏中枢，印第安那大学(Indiana University)金赛研究所(Kinsey Institute)的资深科学家詹森(Erick Janssen)说，这种刺激作用就好像是吃巧克力或是赌赢了钱所产生的效果。
Much of that is due to chemistry—the rush of hormones and neurotransmitters that rise and fall during sexual activity. Arousal boosts dopamine, which activates the brain's centers of craving and reward 'just like chocolate and winning at gambling,' says Erick Janssen, a senior scientist at the Kinsey Institute at Indiana University.
Sex also increases oxytocin, known as the 'cuddle hormone,' which promotes bonding, reduces fear and stimulates endorphins, the body's natural painkillers, which is why sex can bring temporary relief from back pain, migraines and other body aches.
性高潮过后，多巴胺水平迅速下降，催乳素水平上升，使人在产生满足感的同时也有了困意，这种现象在男人身上尤其明显。对性与健康的关系进行过大量研究的西苏格兰大学(University of the West of Scotland)心理学家布罗迪(Stuart Brody)说，这是性爱过后愉悦而放松的感觉。当然，时间节点的掌握并不总是那么完美。在2006年一项对一万名英国男子的调查中，有48%的人承认他们在“嘿咻”的过程中就已经睡着了。
Dopamine levels plummet after orgasm, and levels of prolactin rise, bringing on feelings of satisfaction and sleepiness, particularly in men. 'That's the nice, relaxed feeling afterwards,' says Stuart Brody, a psychologist at the University of the West of Scotland who has conducted numerous studies on sex and health. Of course, timing isn't always perfect. In a 2006 survey of 10,000 British men, 48% admitted to having fallen asleep during sex.
All together, this chemical cascade has a lasting effect that helps people handle stress, which Dr. Brody showed in a study in the journal Biological Psychology in 2005. He had 24 women and 22 men keep diaries of their sexual activities for two weeks, then took their blood pressure while they were told to give an impromptu speech to a hostile audience and do rapid math calculations in their heads. Those who had had traditional sexual intercourse during the fortnight had smaller blood pressure spikes and recovered more quickly than those who engaged in other forms of sex or none at all.
Sex is also touted as good exercise—but the effect is actually modest. Although couples obviously differ, sex generally burns an estimated five calories per minute, or roughly 50 to 150 calories total. Calculated another way, orgasm uses 3 to 4 METs (metabolic equivalent tasks, a measure of physical intensity)—the equivalent of light housekeeping.
Sex does increase heart rate and blood pressure—as high as 125 beats per minute and to 160 peak systolic rate—about as much as walking up a flight or two of stairs. And several studies suggest that having it regularly can protect against cardiovascular problems. One British study found that men who reported having three or more orgasms per week experienced 50% fewer heart attacks than those who engaged less frequently—perhaps because orgasm triggers the release of the hormone DHEA (dehydroepiandrosterone), which helps with circulation and arterial dilation.
On the other hand, erectile dysfunction can be an early indicator of cardiovascular problems—and when drugs such as Viagra first came on the market, some cardiologists feared sex could be dangerous to men with underlying heart problems. In general, such fears have proven unfounded. Cases of sudden death during sex are actually very rare, according to studies in Germany, Japan and Korea. But they are more likely to occur during extramarital sex.
Frequent sex may benefit men's health another way: by boosting testosterone, which in turn is linked to stronger muscles, more energy and better cognition. (Sex's effect on testosterone was shown in a now-famous article in Nature in 1970. A man stranded on a remote island with no women saw his beard stop growing. Then it resumed when he returned to civilization and sex again.)
性爱还能改善女性的情绪——不过对于它究竟是如何产生这种效果的，人们说法不一。2002年对纽约州立大学奥尔巴尼分校(State University of New York in Albany) 293名大学女生进行的研究发现，拥有性生活并且不采取保护措施的女性出现抑郁的可能性要小于其性伙伴使用安全套的女性或是根本没有性生活的女性。研究人员指出，精液中含有睾丸激素、雌激素、催乳素和前列腺素，它们通过阴道壁进入血液，令女性精神振奋。但提倡安全性行为的团体则补充说，由于性生活过程中没有采取防护措施而产生了意料之外的后果——怀孕以及性传播疾病——将会大大地挫伤情绪。
Sex also improves women's moods—although how it does is controversial. One 2002 study of 293 college women at the State University of New York in Albany found that those who engaged in unprotected sex were less likely to be depressed than those whose partners use condoms or who don't have sex at all. The researchers noted that semen contains testosterone, estrogen, prolactin and prostaglandins, which can pass through vaginal walls into the bloodstream and elevate mood. But safe-sex groups add that the unintended results of unprotected sex—pregnancy and sexually transmitted diseases—can put quite a damper on mood.
一些最令人振奋的研究结果显示，规律的性生活能降低罹患某些癌症的风险。《美国医学会杂志》(Journal of the American Medical Association) 2004年刊登的一项针对2.9万名男性医疗保健从业人员进行的研究发现，射精次数最为频繁的男性——每月至少21次——患前列腺癌的风险要远远低于每月射精次数为四至七次的男性。
Some of the most intriguing findings suggest that frequent sex can lower the risk of some types of cancer. A 2004 study of 29,000 male health professionals in the Journal of the American Medical Association found that those who reported having the most frequent ejaculations—21 or more a month—had a much lower risk of prostate cancer than those reporting four to seven per month.
'Emptying the tank every once in awhile is probably good for the prostate,' Dr. Goldstein says. Still, the authors noted that the data 'may have contained some inaccuracy' since it asked men, some in their 80s, to recall how often they ejaculated each month four decades earlier.
Similarly, a 1989 study in France found that women who had sex infrequently or not at all had three times the risk of breast cancer compared to those who had sex more frequently—but the possible biological mechanism is less clear.
一些研究还显示，总体而言性生活可以延年益寿。《英国医学杂志》(British Medical Journal)刊登的一项研究发现，相比起每周有一次性生活的男性，每月性生活次数不足一次的男性在未来十年中死亡的可能性是前者的两倍。杜克大学(Duke University)在25年时间中对270名年龄在60至96岁的男性和女性进行了研究，结果发现男性的性行为越多，他们的寿命就越长。而那些说她们很享受性生活的女性要比性冷淡的女性多活七到八年。不过诸如智力、健康、运动等因素也对延年益寿有着影响。
Several studies also suggest that having sex extends life in general. A study in the British Medical Journal found that men who had sex less than once per month were twice as likely to die in the next 10 years than those who had sex once per week. A 25-year study of 270 men and women aged 60 to 96 conducted at Duke University found that the more men had sex, the longer they lived. Women who said they enjoyed their sex lives lived seven to eight years longer than those who were indifferent. But factors such as intelligence, health and activities also played a role in living longer, too.
So should people ramp up their sexual activity to be healthier?
Not necessarily. 'The 'more is better' prescription is too simplistic,' says the Kinsey Institute's Dr. Janssen. 'What we've learned from all our years of research is that what's important is the satisfaction and the meaning we attach to sex.' In short, 'if you're having sex in a frequency and in a way that is compatible with who you are, then that's healthy.'
2011-11-17 00:41 编辑：loveyystyle