A genetic mutation that allows people to feel fully rested with fewer than six hours sleep a night has been identified by studying a family who get by on less than average. It is the second such finding in recent months.科学家通过对一个家庭的研究，找到了一种可以使人在每晚睡眠不足6小时的情况下获得充份睡觉的基因突变。这个家庭的成员每日睡眠中时长高于平均水平。

这是近几个月来第二个针对这一问题的同类找到。Ying-Hui Fu at the University of California, San Francisco, and her colleagues have been seeking out and studying families in which some people seem to need less sleep than normal. They have been looking for the gene variants that might be responsible, and genetically engineering these variants into mice to confirm their effect.加州大学旧金山分校的傅嫈惠和她的同事们仍然在找寻和研究那些所须要睡眠中多于平均水平的家庭。他们仍然在找寻有可能起起到的基因变异，并通过基因技术将这些变异的基因植入老鼠体内以证实其起到。Her team has found several mutations make people need less sleep. In August, Fus team reported that a mutation in a gene called ADRB1 allows 12 members of a family to sleep as little as 4.5 hours per night without feeling tired. This gene codes for a receptor protein common in a brain region called the dorsal pons, known to regulate sleep.她的团队早已找到了几种基因突变不会使人们必须较少的睡眠中。

今年8月，傅嫈惠的研究小组报告称之为，ADRB1基因突变使一个家庭的12名成员每晚只睡觉4.5小时而会深感疲惫。这种基因为一种受体蛋白编码，这种蛋白在大脑中的脑桥背侧区域很少见，这一区域负责管理调节睡眠中。

Now the team has found a mutation in a gene called NPSR1 in another family in which some people report feeling fully rested after much less sleep than average. Of the two members of this family whose sleep habits they studied, one averaged 5.5 hours a night and the other just 4.3 hours.现在，研究小组在另一个家庭中找到了NPSR1基因突变，一些家庭成员报告说道，他们在睡眠中时间相比之下多于平均水平的情况下，依然深感精力充沛。他们研究了其中两名家庭成员的睡眠中习惯，一人平均值每晚睡觉5.5小时，另一人仅有睡觉4.3小时。NPSR1 codes for a protein receptor in the brain known to be involved in arousal and sleep behaviour. When the team engineered the mutation into mice, they slept less without any obvious effect on health or memory.NPSR1基因为大脑中一种参予唤醒和睡眠中不道德的蛋白质受体编码。

当研究小组把这种突变基因植入老鼠体内时，它们的睡眠中时间增加了，但对身体健康和记忆力没显著影响。Another variation in NPSR1 has previously been linked to people requiring 20 minutes less sleep than average, based on studies of tens of thousands of people.此前针对上万人的研究找到，NPSR1基因的另一种变异与所须要睡眠中时间比平均值较少20分钟的人有关。On average, people need 8 hours sleep a night. In most people, sleeping less than 6 hours a night results in a marked decline in cognitive abilities within days. Over long periods, sleep deprivation can contribute to many disorders, including obesity, heart disease, high blood pressure, diabetes and depression.平均值而言，人们每晚必须8小时的睡眠中。

对大多数人来说，每晚睡眠不足6小时不会造成理解能力在几天内明显上升。长时间缺少睡眠中不会造成许多疾病，还包括体重增加、心脏病、高血压、糖尿病和抑郁症。As far as Fus team has been able to tell, however, people who sleep less because they have one of these gene variants are healthy and dont appear to suffer any ill effects. However, to be absolutely sure would require long-term studies involving large numbers of people, which isnt feasible.然而，就傅嫈惠的研究小组熟知，那些因为享有这些基因变异而睡眠中较较少的人是身体健康的，而且或许没任何不良影响。但要想要几乎确认，就必须展开牵涉到大量人群的长年研究，这是不不切实际的。

Right now, we cannot say for sure, says Fu.傅嫈惠说道：“现在，我们还不过于认同。”In theory, if these gene variants provided a big advantage, evolution should have made them common – yet they appear to be rare. It might be, say, that sleeping less only became an advantage after the development of lights. But other advantageous gene variants that appeared only recently in human history, such as those allowing adults to digest milk, became widespread very rapidly.从理论上谈，如果这些基因变异获取了一个极大的优势，演化应当不会使它们显得广泛，但目前显然还很少见。这有可能是因为，较少睡只是在灯光发明者之后才沦为一种优势。

但是其他不利的基因变异，比如那些容许成年人消化牛奶的基因变异，在人类历史上只是最近才经常出现的，却很快传播出去。It might be possible to develop drugs that mimic the effects of these mutations. However, as NPSR1 is also involved in processes such as stress, anxiety and fear, there is a risk of nasty side effects.研究人员需要研发仿效这些基因突变的药物，但由于NPSR1基因也与压力、情绪和不安等情绪有关，因此有可能造成相当严重的副作用。

Expect more reports soon. Fu say her team has already discovered more sleep-shortening mutations.我们期望旋即之后能有更加多的报导。傅嫈惠说道，她的团队早已找到了更好与睡眠中时间较短有关的基因突变。

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