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我们真需要睡七个小时?一项新研究持否定态度

更新时间:2016-1-25 9:27:01 来源:纽约时报中文网 作者:佚名

Do We Really Need to Sleep 7 Hours a Night?
我们真需要睡七个小时?一项新研究持否定态度

For years, public health authorities have warned that smartphones, television screens and the hectic pace of modern life are disrupting natural sleep patterns, fueling an epidemic of sleep deprivation. By some estimates, Americans sleep two to three hours fewer today than they did before the industrial revolution.

多年来,公共卫生部门一直警告人们,智能手机、电视屏幕和现代生活的紧张节奏破坏了人的天然睡眠模式,助长了睡眠剥夺(sleep deprivation)的泛滥。据估计,美国人现在每天的睡眠时间比工业革命前缩短了两到三个小时。

But now a new study is challenging that notion. It found that Americans on average sleep as much as people in three different hunter-gatherer societies where there is no electricity and the lifestyles have remained largely the same for thousands of years. If anything, the hunter-gatherer communities included in the new study — the Hadza and San tribes in Africa, and the Tsimané people in South America — tend to sleep even less than many Americans.

如今,一项新研究对上述观念提出了挑战。该研究调查了三个不同的狩猎-采集社会族群:非洲的哈扎人(Hadza)和桑人(San),以及南美洲的齐玛内人(Tsimané),这些人基本上仍沿袭着几千年前的生活方式,也不会用电,但他们的睡眠时间与美国人的平均水平并没有什么差别——如果一定说有的话,他们甚至睡得比很多美国人还要少。

The findings are striking because health authorities have long suggested that poor sleep is rampant in America, and that getting a minimum of seven hours on a consistent basis is a necessity for good health. Many studies suggest that lack of sleep, independent of other factors like physical activity, is associated with obesity and chronic disease.

这些调查结果令人震惊,因为卫生部门早就提出,美国人普遍睡眠不足;而且,要保持身体健康,至少要保证每天睡足七小时。大量研究显示,缺乏睡眠与肥胖和慢性疾病相关,且这种关联与体力活动等其他因素无关。

Yet the hunter-gatherers included in the new study, which was published in Current Biology, were relatively fit and healthy despite regularly sleeping amounts that are near the low end of those in industrialized societies. Previous research shows that their daily energy expenditure is about the same as most Americans, suggesting physical activity is not the reason for their relative good health.

然而,在这项发表在《当代生物学》杂志(Current Biology)上的新研究中,三个狩猎-采集族群的成员的日常睡眠时间即使放在工业化社会中也算是短的,但他们的身体却十分健康且身材健美。此前的研究显示,他们的日常能量消耗与大多数美国人差不多,这表明体力活动并非他们身体相对健康的原因。

The prevailing notion in sleep medicine is that humans evolved to go to bed when the sun goes down, and that by and large we stay up much later than we should because we are flooded with artificial light, said Jerome Siegel, the lead author of the new study and a professor of psychiatry at the Semel Institute of Neuroscience and Human Behavior at U.C.L.A.

这项新研究的主要作者,加州大学洛杉矶分校(UCLA)神经科学与人类行为研究所(Semel Institute of Neuroscience and Human Behavior)的精神病学教授杰尔姆·西格尔(Jerome Siegel)说,睡眠医学中的普遍观点是,人类在演化过程中已经习惯于日落而息,而现代社会中充斥着的人造光令我们大大延迟了该入睡的时间。

But Dr. Siegel and his colleagues found no evidence of this. The hunter-gatherer groups they studied, which slept outside or in crude huts, did not go to sleep when the sun went down. Usually they stayed awake three to four hours past sunset, with no light exposure other than the faint glow of a small fire that would keep animals away and provide a bit of warmth in the winter. Most days they would wake up about an hour before sunrise.

但西格尔博士和同事们并没有找到支持这一观点的证据。他们所研究的狩猎-采集族群的成员都睡在室外或粗糙的小屋中,但这些人并没有在太阳下山后立刻去睡觉。通常,他们在日落后三到四个小时里仍然清醒着,而且除了用以驱赶野生动物并在冬天聊以取暖的微弱火光之外,他们别无其他光源。一年中的大多数日子,他们都在日出前一小时左右起床。

In a typical night, they slept just six and a half hours — slightly less than the average American. In the United States, most adults sleep seven hours or more a night, though a significant portion of the population sleeps less.

于是,一般而言,他们每晚只睡六个半小时,比普通美国人还略少一些。在美国,大多数成年人每晚至少睡眠七小时,不过,也有很大一部分人睡眠较少。

“I think this paper is going to transform the field of sleep,” said John Peever, a sleep expert at the University of Toronto who was not involved in the new research. “It’s difficult to envision how we can claim that Western society is highly sleep deprived if these groups that live without all these modern distractions and pressing schedules sleep less or about the same amount as the average Joe does here in North America.”

“我认为这篇论文将给睡眠领域带来变革,”多伦多大学(University of Toronto)的睡眠专家约翰·皮弗(John Peever)说,他本人没有参与这项新研究。“要是这些没有受到现代化的干扰,也没有紧迫的日程安排的人们睡眠时间并不比北美的普通人更长,很难想象我们要如何断言西方社会的人们遭受着高度的睡眠剥夺。”

On its website, the Centers for Disease Control and Prevention calls insufficient sleep a public health problem in America, “which may be caused by broad scale societal factors such as round-the-clock access to technology and work schedules.” The agency says that adults require seven to eight hours of sleep daily, and that a third of Americans typically sleep less than this amount.

美国疾病控制和预防中心(Centers for Disease Control and Prevention)在自家网站上称睡眠不足是美国的公共卫生问题,“这可能是由多种多样的社会因素,如终日接触高科技以及工作时间安排等造成的。”该机构表示,成年人每天需睡眠七到八小时,而三分之一的美国人常常达不到这一要求。

In June, two of the leading sleep associations — the American Academy of Sleep Medicine and the Sleep Research Society — issued recommendations stating that adults should sleep seven or more hours on a regular basis. The groups recommended that people who are concerned they are not getting the right amount of sleep consult a health care provider.

去年6月,两个主要的睡眠学会——美国睡眠医学会(American Academy of Sleep Medicine)和睡眠研究学会(Sleep Research Society)发布建议,指出成年人应保证至少七小时的日常睡眠时间。这两个组织还建议,如果你担心自己没有获得适量睡眠,应向医疗保健提供者咨询。

“Sleeping less than seven hours per night on a regular basis is associated with adverse health outcomes, including weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression and increased risk of death,” the recommendations stated.

建议还指出:“睡眠经常不足七小时与不良健康后果相关,包括体重增加和肥胖、糖尿病、高血压、心脏病和中风、抑郁症和死亡风险增加等。”

Nathaniel Watson, the president of the American Academy of Sleep Medicine, said that the recommendations were based on a review of 5,000 studies that assessed sleep and disease in humans. He said most of the studies were based on self-reporting of how much people slept, which tends to be an overestimate because people report the overall time they spend in bed — not the amount of time they were technically asleep, which is usually less.

美国睡眠医学会主席纳撒尼尔·沃森(Nathaniel Watson)称,他们提出上述建议,依据的是一项关于5000项评估人类睡眠和疾病的研究的综述。他还说,这其中的大部分研究都基于对睡眠时间的自我报告,它们往往较实际值偏高,因为人们报告的是他们在床上度过的总时间,并非严格说来的睡眠时间,而后者显然要短于前者。

Dr. Watson pointed out that in the new study, the hunter-gatherer societies were found to have a sleep period — meaning the time they were actually in bed — of roughly seven to eight and a half hours, which he said was consistent with his group’s recommendations.

沃森博士指出,在最近发表的那项新研究中,狩猎-采集社会族群中的睡眠周期(亦即他们实际上待在床上的时间)大约为七到八个半小时,他认为这与他们学会提出的建议是一致的。

He said the question of how much sleep people require was a delicate one.

他还说,人到底需要多少睡眠是一个复杂的问题。

“Really it’s just the amount that allows people to wake up feeling refreshed and alert,” he added.

“其实,它应该是指能让人们醒来后感觉神清气爽、思维敏捷所需的时间,”沃森博士补充道。

But Dr. Siegel said he worried that putting a number on the amount of sleep people require could push those who get less to resort to using sleeping pills, which carry severe side effects. About 5 percent of Americans take sleeping pills, a percentage that has doubled in the past two decades.

但西格尔博士表示他很担心如果对人们必需的睡眠时间加上个数量限制,那些睡眠时间“不达标”的人可能会因此去吃安眠药,而这些药物都有严重的副作用。目前,约5%的美国人在服用安眠药,较之20年前翻了一番。

Jim Horne, the director of the Sleep Research Center at Loughborough University in England, called the new study “excellent and very timely,” and he said it suggests that sleep quality is much more important than quantity.

罗浮堡大学(Loughborough University,位于英格兰)睡眠研究中心(Sleep Research Center)的主任吉姆·霍恩(Jim Horne)认为这项新研究“杰出且非常适时”,并指出,它表明,睡眠质量比数量更为重要。

“There is this concern in the Western world that we need more sleep and that if you get less than seven hours you’re liable to suffer from obesity and diabetes and heart disease,” he said. “But the average amount of sleep in these people was well under what is recommended to us as adequate sleep, and these were very healthy people who are not suffering chronic disease and insomnia.”

“西方世界中普遍存在着这么一种担忧,认为我们需要更多的睡眠,而且如果每晚睡不够七个小时,就容易患肥胖症、糖尿病和心脏病,”他说。“可看看(研究中的)这些人,他们的平均睡眠时间比建议的充足睡眠时间少得多,但他们非常健康,既没有患慢性疾病,也不曾失眠。”

Among sleep researchers it is widely believed that people sleep differently today than they did 150 years ago. Many argue that the invention of the electric light bulb in the late 1800s — and all the artificially lit environments that followed — dramatically changed our sleep patterns. Exposure to artificial light at night, whether from light bulbs or computer screens, throws off the body’s biological clock, delaying and reducing sleep, experts say.

睡眠研究者普遍认为,人们如今的睡眠模式与150年前截然不同。许多人主张,19世纪末电灯泡的发明,以及其后所有的人工照明环境都大大改变了我们的睡眠模式。专家称,无论是灯泡还是电脑屏幕,都会让人在夜间暴露在人造光下,扰乱人体的生物钟,推迟并缩短睡眠。

Some historians have also argued that it is not natural for people to sleep straight through the night. They say that before the introduction of artificial light it was normal for people to sleep in two intervals separated by an hour of wakefulness, a phenomenon known as segmented sleep, or “first” and “second” sleep.

还有一些历史学家认为,彻夜连续睡眠并不符合人体的自然规律。他们说,在发明人造光之前,人们的睡眠常分为两段,中间间隔一小时的清醒时间,这种现象称为分段式睡眠,或“第一段”和“第二段”睡眠。

But Dr. Siegel said he always questioned those assertions because there were no rigorous studies of sleep behaviors back then. He and his colleagues decided that one way to get some insight was to study cultures relatively unaffected by artificial light.

但西格尔博士说,他对这些断言一直抱有怀疑态度,因为当时并不曾对睡眠行为进行过严谨的研究。他和同事们认定,弄清楚这些问题,途径之一是研究那些相对未受到人造光源影响的文明。

Among those they chose to follow were the Hadza people, who spend their days hunting and foraging in northern Tanzania, much as their ancestors have for tens of thousands of years; the San of Namibia, who have lived as hunter-gatherers in the Kalahari for at least 20,000 years; and the Tsimané, a seminomadic group that lives in the Andean foothills of Bolivia, near the farthest reaches of the human migration out of Africa.

他们选择了以下族群作为随访对象:居住在坦桑尼亚北部的哈扎人,他们像其千万年前的先祖一样,终日狩猎采食;生活在纳米比亚的桑族人,他们在喀拉哈里沙漠(Kalahari)狩猎-采集已有至少2万年的历史;以及在玻利维亚的安第斯山麓过着半游牧生活的齐玛内人,他们差不多是人类走出非洲后迁移得最远的一支。

Members of the various tribes were fitted with small wristwatchlike devices that tracked their sleep patterns and their exposure to light across the seasons.

研究人员给这几个部落的成员配备了类似腕表的小装置,用以跟踪他们的睡眠模式以及他们在各个季节的光暴露情况。

The researchers found that in addition to sleeping roughly similar amounts each night, the three groups rarely took naps during the day and did not sleep in two separate intervals at night.

研究人员发现,除了每晚睡眠时间大致相同之外,三组研究对象在白天都基本不会小睡,夜晚的睡眠也并未分成两段。

Dr. Siegel said it was remarkable how closely their sleep patterns overlapped despite the distances between them.

西格尔博士说,值得注意的是,尽管他们之间相隔十万八千里,睡眠模式却基本相同。

“The Hadza and the San live in the area where we know humans evolved, and then the Tsimané live in some sense at the end of the human migration,” he said. “The fact that we see very similar sleep times gives me great confidence that this is how all of our ancestors slept.”

“哈扎人和桑族人居住在众所周知的人类起源之地,而齐玛内人则生活在人类迁徙足迹所及的最远处,”他说。“我们发现他们的睡眠时间非常相似,该事实令我自信地认为:这就是我们所有祖先的睡眠模式。”

Their sleep did not seem to be problematic. Chronic insomnia, which affects 20 percent to 30 percent of Americans, occurred in just 2 percent of the hunter-gatherers. The San and the Tsimané did not even have a word for it in their languages.

他们似乎并不存在睡眠问题。困扰20%到30%的美国人的慢性失眠,在狩猎-采集族群中的发生率仅有2%。桑族人和齐玛内人的语言中甚至都没有“失眠”这个词。

Dr. Siegel said that ambient temperature may be a major factor. The groups did not go sleep at sunset and they did not wake up at sunrise, suggesting that light exposure did not have much influence on their sleep patterns. But they almost always fell asleep as temperatures began to fall at night, and they would wake up right as the temperatures were rising again.

西格尔博士说,环境温度可能是一个重要因素。这些人没有在日落时入睡,也没有在日出时醒来,这表明光照暴露对他们的睡眠模式并没有太大的影响。但他们几乎总是在夜晚气温开始下降时入睡,在气温回升时醒来。

This suggests that humans may have evolved to sleep during the coldest hours of the day, perhaps as a way to conserve energy, Dr. Siegel said. If falling temperatures at night are a signal to our bodies that it is an ideal time to go to sleep, then that could be one reason chronic insomnia is so prevalent in industrialized societies.

这表明,人类或许是在演化中形成了在一天中最冷的时间睡觉的习惯,这可能是一种节能的方式,西格尔博士说。如果夜间气温下降是一个信号,提醒我们的身体入睡的理想时间到了,那么,这说不定就是工业化社会中慢性失眠如此普遍的原因之一。

“Today we sleep in environments with fixed temperatures, but none of our ancestors did,” Dr. Siegel said. “We evolved to sleep in a natural environment where the temperature falls at night. Whether we can treat insomnia by putting people in an environment where the temperature is modulated in this way is something to be studied in the future.”

“如今的我们在恒温环境中睡眠,这可是我们的祖先从未经历过的,”西格尔博士说。“在我们的演化过程中,可一直是在夜间气温下降的自然环境中睡觉的。至于能否通过将人置身于可将温度按这一模式调整的环境中来治疗失眠,还有赖于将来的研究。”

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