Why you can’t sleep

FORTUNE — David K. Randall begins Dreamland, 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.’’

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.

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