我们为什么睡不着？

    如果真是这样的话，为什么这些药物的使用者坚称自己睡得更好了呢？兰德尔的解释是，安必恩和鲁尼斯塔等药物会导致“顺逆行遗忘（anteretrograde amnesia），使大脑暂时很难形成新的短期记忆。”因此，他坚称，即使整个晚上辗转反侧，当你早上醒来时也根本意识不到这一点（许多医生认为，无知或许对我们有好处——这是宽慰话；我们不记得的失眠不会让我们产生焦虑感）。

    兰德尔在书中提到了许多与打瞌睡的历史和进化生物学有关的事实，非常引人入胜。他运用口语化、易于阅读的语言，诠释了男人和女人睡眠方式存在的差异，以及夫妇分开睡为什么效果反而更好等问题。此外，他还声称，床垫无关乎睡眠质量，他援引的一项研究显示，不管是在混凝土板上，还是在加热的高科技床垫上，受试者都睡得一样好。然而，就总体而言，兰德尔没有、也不打算为夜不能寐者提供太多具有操作性的建议。

    这本书提及的最可行的睡眠诀窍或许与体育博彩有关。我们的昼夜节律时常让我们在大约早上9点到下午2点左右这段时间内保持警觉，“在这个时间点上我们需要开始考虑小睡一下，”兰德尔写道。下午6点左右时，我们的身体获得另一轮能量注入，效果可持续至晚上10点钟左右。“力量、柔韧性和反应时间会激增。”你或许会问，这跟“周一橄榄球之夜（Monday Night Football）”有什么关系呢？无论比赛地点是在什么地方，周一的橄榄球赛通常都在美国东部时间下午8点半开赛，因此对于西海岸球队而言，比赛时间总是下午5点半——正好是他们的夜晚能量获得提升的时候。而东海湾球队“在首节比赛结束之前，其身体的巅峰状态就已结束。”研究人员发现，在过去25年间，无论是否拥有主场优势，西海岸球队在大约63%的时间里都击败了东海岸球队，平均多出了2次触地得分，并且在70%的时间里赢得得分差。谢谢你，大卫•兰德尔！

    《梦境》一书最强大、最挥之不去的效果就是一种失落感：我们曾经睡得如此之好，睡得如此动人，这种美好经历再也不会有了！我们基本上已经放弃了打瞌睡的习惯，甚至在一些曾经把午睡奉为一项人权的国家也是如此（尽管广泛的研究显示，短短15分钟的午睡就可以提高一个人的认知能力）。

    当兰德尔揭示出另一个已经被我们舍弃的仪式（我们“夜间生活”一段既甜蜜又隐秘的间隔期）时，这种头痛感就加剧了。乔叟的《坎特伯雷故事集》（Canterbury Tales）和其他早期文本都提到过“首次睡眠”和“二次睡眠”。欧洲人过去习惯从日落时分一觉睡到午夜之后，在那时他们通常会心满意足地保持大约1小时的清醒，然后再继续睡觉至太阳升起的时候（最近一项研究显示，长时间撤回人造光也能够产生同样的间隔期）。在这段清醒的夜半时分，人们通常会“祈祷、阅读、沉思或者做爱。”

    研究显示，这个间隔期“或许是他们一生中最放松的时间段，”标志是身体产生出更多的

    催乳激素。这种激素有破除压力的效果，它“正是人们在极度兴奋后感到放松的原因所在。”一些非工业化社会依然在实践着这种分割式睡眠，但在西方国家，这一神奇的时光似乎已无法挽回了。正如兰德尔的著作所示，我们的睡眠时常是一段异常艰辛、最终以猛然觉醒结束的旅程。

    译者：任文科

    If that's the case, why do users of these meds insist they sleep better? Randall's explanation is that drugs like Ambien and Lunesta cause "anteretrograde amnesia … making it temporarily harder for the brain to form new short-term memories.'' So even if you toss and turn all through the night, he maintains, you simply won't realize it when you wake up in the a.m. (Many doctors think that ignorance may do us some good, placebo-style; the insomnia we don't remember won't make us anxious.)

    Randall presents a pile of often-fascinating facts on the history and evolutionary biology of the nod. In colloquial, easy-reading prose, he explains how men and women sleep differently, and why couples would do better to sleep apart. He also argues that mattresses don't matter, citing a study in which subjects slept just as well on a concrete slab as on a heated, high-tech prototype mattress. In general, however, Randall doesn't -- and doesn't set out to -- offer much practical advice that the individual toss-and-turner can use.

    The most actionable tip in the book may be on sports betting. Our circadian rhythms keep us alert from around 9 a.m. until 2 p.m. or so, "which is when we start thinking about a nap,'' Randall writes. At round 6 p.m., the body gets another energy infusion that lasts until roughly 10 p.m. "Strength, flexibility and reaction times surge." What does all that have to do with Monday Night Football, you ask? MNF games kick off at or just after 8:30 p.m. EST, no matter where they're played, so it's always 5:30 p.m. for West coast teams -- just about time for their evening power boost. East coast teams "are past their natural performance peaks before the first quarter ends.'' Over 25 years researchers studied, West coast teams defeated Easterners 63% of the time, by an average of two touchdowns -- and beat the point spread 70% of the time, regardless of who was home or away. Thank you, David K. Randall!

    One of Dreamland's strongest and most lingering after-effects is a sense of loss, the notion that we once slept so much better -- even beautifully -- and never will again. We've largely abandoned the nap, even in countries where the siesta was once a human right. (This in spite of extensive research showing that as little as 15 minutes of napping improves cognitive abilities.)

    That ache increases when Randall reveals a different ritual we've forsaken, a sweet, secret interval in our "life after dark.'' Chaucer's Canterbury Tales and other early texts refer to "first sleep'' and "second sleep.'' It seems that Europeans used to sleep from sundown or thereabouts until after midnight, when they would regularly, contentedly stay awake for an hour or so, and then snooze until sunrise or morning. (A recent study that withdrew artificial light for an extended period produced these same intervals.) That awake-break was spent "praying, reading, contemplating … or having sex.''

    Research indicates this period was "probably the most relaxing block of time in their lives,'' marked by higher production of prolactin, a stress-busting hormone "responsible for the relaxed feeling after an orgasm.'' Some non-industrialized societies still practice split sleep, but here that magic hour seems irretrievable. As Randall's book shows, ours is all too often a troubled sleep, followed by rude awakenings.