文章来源：原版英语

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

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

　　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。

　　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。

　　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。

　　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.'

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

　　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。

　　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。

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

　　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。

　　He told NPR: "I definitely think that's happening out there. I think many women are chronically sleep-deprived because of their work obligations."

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

　　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."

　　那些称自己太累而不愿同丈夫做爱的女性也许并不是在找借口。

　　哈佛大学的一项研究发现，男性和女性的生物钟并不一致——女性习惯很早就寝就是因为这个原因。

　　这篇研究报告称，早寝是女性的天性，这样她们就不用在做爱时考虑其他事情。

　　研究人员召集了157名志愿者，让他们在波士顿一个没有窗户的睡眠实验室里生活8个礼拜。在这个实验室里他们同外部世界完全隔绝，没有时间概念，这样他们的生物钟就能回归到最自然的状态。

　　珍妮？达芙是这项研究的发起人之一，她在接受美国国家公共电台采访时说：“试验中我们发现女性的生物钟平均要比男性的快6分钟，所以她们总是早睡早起。”

　　而光线等因素又会使这6分钟的差别继续扩大。

　　同男性相比，女性失眠的几率要高出50%，特别是对那些习惯早起的女性，因为她们醒了之后就再也睡不着了。这就解释了为何女性经常一大清早就起床，而她们的丈夫还呼呼大睡直至日上三竿。

　　超过三分之一的女性体内生物钟过快，不到24小时就能走完一天的周期。

　　对于这些女性来说，把生物钟调回到最自然的状态就尤为重要。

　　哈佛大学医学院医生查尔斯？赛斯勒尔是一名睡眠医学专业的教授，他表示，目前有数以万计的女性因生物钟过快而痛苦不堪。

　　他对美国国家公共电台的记者说：“情况就是这样，女性常因为工作上的事情而长期睡眠不足。”

　　不过他也补充说女性朋友并没有意识到早起也是造成她们失眠的原因。

　　他说：“许多女性朋友很喜欢早上四、五点钟起床那种感觉。她们感觉内心平静安宁。当周围的一切还沉浸在梦乡中时，就处理好了一大堆事情——她们可不愿失去这种感觉。”