揭祕:女性爲何在房事前感覺疲憊

It turns out women who say they are just too tired for sex may not be making excuses after all.

那些稱自己太累而不願同丈夫做愛的女性也許並不是在找藉口。

According to a Harvard study, they run on a different biological sleep clock to men - and need to go to bed earlier because of it.

哈佛大學的一項研究發現，男性和女性的生物鐘並不一致——女性習慣很早就寢就是因爲這個原因。

According to the study, for many women their natural instinct is to go to bed early - so sex can be the last thing on their minds in the evening.

這篇研究報告稱，早寢是女性的天性，這樣她們就不用在做愛時考慮其他事情。

It's based on results produced by 157 people who spent eight weeks in a windowless sleep lab in Boston. They were isolated from all cues about the time in the outside world, allowing their body clocks to go back to natural circadian rhythms.

研究人員召集了157名志願者，讓他們在波士頓一個沒有窗戶的睡眠實驗室裏生活8個禮拜。在這個實驗室裏他們同外部世界完全隔絕，沒有時間概念，這樣他們的生物鐘就能迴歸到最自然的狀態。

Jeanne Duffy, one of the study's authors, told NPR: 'What we found was that the cycle length of the biological clock in women was six minutes faster on average than it was in men, making them much more likely to be early birds rather than night owls.'

珍妮 達芙是這項研究的發起人之一，她在接受美國國家公共電臺採訪時說：“試驗中我們發現女性的生物鐘平均要比男性的快6分鐘，所以她們總是早睡早起。”

That six-minute variation can be further amplified by factors such as when light first hits the eye.

而光線等因素又會使這6分鐘的差別繼續擴大。

They report insomnia around 50 percent more frequently than their male counterparts, especially the early morning kind, where they wake up and cannot get back to sleep. It helps explain why women are often up with the lark, while their partners stay slumbering long into the morning.

同男性相比，女性失眠的機率要高出50%，特別是對那些習慣早起的女性，因爲她們醒了之後就再也睡不着了。這就解釋了爲何女性經常一大清早就起牀，而她們的丈夫還呼呼大睡直至日上三竿。

Some women - more than one in three - have inner clocks which run particularly fast, so they can complete a daily cycle in less than 24 hours.

超過三分之一的女性體內生物鐘過快，不到24小時就能走完一天的週期。

It is particularly important for these women to reset their internal clocks.

對於這些女性來說，把生物鐘調回到最自然的狀態就尤爲重要。

According to Charles Czeisler, a professor of sleep medicine and a physician at Harvard Medical School, millions of women are fighting against their faster circadian rhythms every day.

哈佛大學醫學院醫生查爾斯 賽斯勒爾是一名睡眠醫學專業的教授，他表示，目前有數以萬計的女性因生物鐘過快而痛苦不堪。He told NPR: "I definitely think that's happening out there. I think many women are chronically sleep-deprived because of their work obligations."

他對美國國家公共電臺的記者說：“情況就是這樣，女性常因爲工作上的事情而長期睡眠不足。”

But he added many women don't see their early bird tendencies as a problem.

不過他也補充說女性朋友並沒有意識到早起也是造成她們失眠的原因。

He said: "There are many women who really enjoy the fact that they can get up at 4 or 5 o'clock in the morning. They have peace and quiet. Before the rest of the world wakes up, they can get an extraordinary amount done - and they wouldn't trade it for the world."

他說：“許多女性朋友很喜歡早上四、五點鐘起牀那種感覺。她們感覺內心平靜安寧。當週圍的一切還沉浸在夢鄉中時，就處理好了一大堆事情——她們可不願失去這種感覺。”