我们为什么睡不着？

    《梦境》（Dreamland）一书探讨的是我们无意识的时刻。作者大卫•兰德尔开篇首先叙述了自己梦游经历的开始。一天夜晚，作者醒来时发现自己躺在其布鲁克林公寓的走廊里，双手正紧握着一只伤腿。这是他的首次梦游经历，很明显（他也记不清楚是怎么回事），他对方向的把控不够熟练，进而撞到了腿。他去医院看病，尔后在一个睡眠实验室呆了一宿，不料却被医生告知这次短途之旅的原因还不清楚，无法给他推荐可靠的治疗之策。兰德尔非常惊讶地发现我们对这一领域的认识如此贫瘠，于是展开了调查，这本书就是他调查的成果。

    开篇讲述自身梦游经历是非常自然的事情，但对像我这样偶尔失眠、以及其他有睡眠问题的人来说，他的不幸遭遇并没有什么让人印象深刻的地方。他的腿受了点轻伤？而且只有一次？这算什么大不了的睡眠事故啊！我想这个兰德尔肯定是个年轻人，书中使用的作者照片似乎证明了这一点【他是路透社（Reuters）的资深记者，《梦境》是他的处女作】“睡眠并不是我们在21世纪头些年应该担忧的事情，”他若有所思地写道。他还说：“在我们大多数人的生活中，睡眠的重要性可能跟使用牙线的重要程度差不多。”

    果真如此吗？我认识的那些不堪生活重压的中年人常常受到睡眠不足的困扰，他们大量服用安眠药，花费数千美元购买花哨的床垫。睡眠不足这个问题几乎跟子女和房子一样，让我们发表了无数单调乏味的长篇大论。对睡眠问题这么高的关注度使得兰德尔这本书备受瞩目——也由此具有非常好的销售前景。

    在这个奇怪的开篇之后，《梦境：探究陌生的睡眠科学》（Dreamland: Adventures in the Strange Science of Sleep）随即以详实的内容对那些个让人苦恼的8小时进行了引人入胜的探索。我们的问题出在什么地方？大背景是：工业革命和托马斯•爱迪生发明的那个讨厌的电光源搞乱了我们的昼夜节律，以及调节睡眠和许多其他基因功能的激素周期。

    大脑中那个微小的、似乎依然处于爬行类动物阶段的松果体也难辞其咎。当它感觉到被延长的黑暗时，它就会产生出诱导睡眠的褪黑激素。然而，兰德尔解释称：“充分的白光，特别是带着一丝蓝色调，宛若蓝天的白光能够诱使松果体误以为依然艳阳高照。”这意味着，正躺在床上使用个人电脑，观看电视或用iPad看电影的你（没错，就是你），正在摁下作者所说的“反向嗜睡按钮”。

    这些因素有助于解释为什么每7个美国人中就有1位有长期的睡眠障碍问题。此外还有一些人有短期的睡眠问题：“每天晚上，大约五分之二的美国成年人都难以入睡或无法持续睡眠，”兰德尔写道。他在书中提及一个由此产生的、在私营部门、特别是美军中迅速兴起的领域：“疲劳管理”。由于兰德尔堆积了太多睡眠不足的士兵和水手犯下致命错误的故事，这本书写到这里时似乎陷入了停顿。他随后做了一个令人大开眼界的预测：到2020年，所有美军士兵都将在手腕上带上睡眠监控器。兰德尔在书中写道：“只需点击几下鼠标，一位指挥官就可以了解他麾下的每位士兵究竟睡了多长时间，并由此确定他或她可能会作出的决策。”

    作者在最令人震惊的（没有双关语意）一章中追溯了安眠药的历史，而且差点对大型制药公司的“嗜睡欺诈”行为进行了指责。仅在美国，这些有力的小药丸就是一门价值300亿美元的生意（2010年数据），比全球人口每年去电影院的花费还稍稍高一些。他指出，在2010年，四分之一美国成年人的药品柜中放有医生开的安眠药。然而，“许多研究显示，类似安必恩（Ambien）和鲁尼斯塔(Lunesta)这样的安眠药并没有显著改善睡眠质量，对于睡眠数量的改善也仅仅是稍好一点而已，”兰德尔写道。

    David K. Randall beginsDreamland, his look at our unconscious hours, by recounting the start of his own Z-journey. The author awakes one night lying in the hallway of his Brooklyn apartment, clutching a wounded leg. He'd sleepwalked for the first time and apparently -- he couldn't remember a thing -- his steering wasn't skillful enough to avoid a leg-on collision. He sees a doctor, then stays overnight in a sleep lab, only to be told that the causes of his jaunt are unclear and no treatments can reliably be recommended. Amazed at how little we know for certain in this realm, Randall investigates, and this book is the result.

    It's a natural place to begin, but to this occasional insomniac and, I suspect, others with sleep problems, his misadventure does not impress. He got a boo-boo on his leg? Once? Big sleeping deal. This Randall must be a younger man, I thought, and his author photo seems to bear that out. (He's a senior reporter for Reuters, and Dreamland is his first book.) "Sleep wasn't something that we were supposed to worry about in the first years of the twenty-first century,'' he muses, adding that "the importance of sleep likely hovers somewhere near that of flossing in most of our lives.''

    Really? The stressed-out middle-agers I know are obsessed with the sleep they're not getting, gobbling Lunesta, and spending thousands on fancy mattresses. Our monologues about (lack of) sleep are almost as tedious as our riffs on children and real estate. This preoccupation is what makes Randall's book such a compelling -- and marketable -- idea.

    After this curious opening gambit, Dreamland, subtitled Adventures in the Strange Science of Sleep, turns out to be an engaging, well-reported exploration of those fraught eight hours. What's our problem? Big picture: the Industrial Revolution and Thomas Edison's pesky electric light screwed up our circadian rhythms, the natural, hormonal cycles that regulate sleep and many other genetic functions.

    The brain's tiny and still-a-bit-too-reptilian pineal gland is also to blame. It produces sleep-inducing melatonin when it senses prolonged darkness. However, Randall explains, "abundant white light -- especially white with a slight blue tint that mimics the sky -- can fool the pineal gland into thinking that the sun is still up.'' That means you over there -- yes, you -- clutching that laptop in bed, or watching the tube, or catching a movie on your iPad -- are pushing what the author calls "reverse snooze buttons.''

    These factors help explain why one out of every seven Americans has a long-term sleep disorder. Then there are the short-termers: "Every night, about two of every five adults in the United States have problems falling asleep and staying asleep,'' Randall writes. He describes the resulting, burgeoning field of "fatigue management,'' in the private sector and especially in the U.S. military. Here the story bogs down a bit as Randall piles on too many examples of sleep-deprived soldiers and sailors making fatal errors. He then makes the eye-opening prediction that by 2020 all U.S. soldiers will wear sleep monitors on their wrists: "With a few clicks of a mouse, a commander will know how many hours each person in the unit has slept -- and, by extension, what kind of decisions he or she will likely make.''

    In the most alarming (no pun intended) chapter, the author traces the history of sleeping pills and comes close to accusing Big Pharma of somnolence fraud. Those potent little pills were a $30 billion business in 2010 in the U.S. alone, or slightly more than the global population spends going to the movies every year. In 2010, he notes, a quarter of U.S. adults had prescription sleeping pills in their medicine cabinets. And yet, Randall writes, "a number of studies have shown that drugs like Ambien and Lunesta offer no significant improvement in the quality of sleep … They give only a tiny bit more in the quantity department, too.''