Roanoke, Virginia -- "Bed is a medicine," instructs an Italian proverb. Increasingly, Americans are inverting that counsel by ingesting sleeping pills to speed their slumber.

With complaints of insomnia mounting, and marketing by drug companies becoming ever more ubiquitous, we are turning in increasing numbers to drugs like Ambien and Lunesta. According to a recent report from the research company IMS Health, pharmacists in the United States filled some 42 million prescriptions for sleeping pills last year, a rise of nearly 60 percent since 2000.

Are we running too quickly to the medicine cabinet? Or is insomnia genuinely reaching epidemic proportions, a consequence perhaps of the frenetic pace of modern life?

In all likelihood, we have never slept so soundly. Yes, the length of a single night's sleep has decreased over the years (upward of 30 percent of adults average six or fewer hours), but the quality of our sleep has improved significantly. And quality, not quantity, sleep researchers tell us, is more important to feeling well rested.

This is not to minimize the torment of insomnia over the course of a restless night. But for most of us, slumber is reasonably tranquil - especially when compared with what passed for a night's rest before the modern era. Despite nostalgic notions about sleep in past centuries, threats to peaceful slumber lurked everywhere, from lice and noxious chamber pots to tempestuous weather.

Worst in this pre-penicillin age was sickness, especially such respiratory tract illnesses as influenza, pulmonary tuberculosis and asthma, all aggravated by bedding rife with mites. One 18th-century diarist recounts that asthma forced her husband to sleep in a chair for months, with "watchers" required to hold his head upright. Among the laboring poor, whose living conditions were horrendous, sleep deprivation was probably chronic, prompting many to nap at midday, much to the annoyance of their masters.

As if these maladies were not enough, we now also know that pre-industrial families commonly experienced a "broken" pattern of sleep, though few contemporaries regarded it in a pejorative light. Until the modern age, most households had two distinct intervals of slumber, known as "first" and "second" sleep, bridged by an hour or more of quiet wakefulness. Usually, people would retire between 9 and 10 o'clock only to stir past midnight to smoke a pipe, brew a tub of ale or even converse with a neighbor.

Others remained in bed to pray or make love. This time after the first sleep was praised as uniquely suited for sexual intimacy; rested couples have "more enjoyment" and "do it better," as one 16th-century French doctor wrote. Often, people might simply have lain in bed ruminating on the meaning of a fresh dream, thereby permitting the conscious mind a window onto the human psyche that remains shuttered for those in the modern day too quick to awake and arise.

The principal explanation for this enigmatic pattern of slumber probably lies in the nocturnal darkness that enveloped pre-industrial households - in short, the absence of artificial lighting. There is a growing consensus on the impact of modern lighting on sleep. The Harvard chronobiologist Charles A. Czeisler has aptly likened lighting to a drug in its physiological effects, producing, among other changes, altered levels of melatonin, the brain hormone that helps to regulate our circadian clock.

In fact, during clinical experiments at the National Institute of Mental Health, human subjects deprived of light at night for weeks at a time exhibited a segmented pattern of sleep closely resembling that related in historical sources (as well as that still exhibited by many wild mammals). The subjects also experienced, during intervals of wakefulness, measurably higher levels of prolactin, the hormone that allows hens to sit happily upon their eggs for long periods.

These elevations of prolactin reinforce historical descriptions of complacent feelings at "first waking" and, back then, probably helped calm people's worries about the night's perils. Prolactin is also what differentiates segmented sleep, with its interval of "non-anxious wakefulness" that nearly resembles a meditative state, from the tossing-and-turning insomnia we medicate against. "Let the end of thy first sleep raise thee from thy repose: then hath the body the best temper; then hath thy soul the least encumbrance," wrote the moralist Francis Quarles.

Remarkably, then, our pattern of consolidated sleep has been a relatively recent development, another product of the industrial age, while segmented sleep was long the natural form of our slumber, having a provenance as old as humankind. (Homer even invoked the term "first sleep" in The Odyssey.) For experts like Dr. Thomas Wehr, who conducted the experiments at the National Institute of Mental Health, some common sleep disorders may be nothing more than sleep's older, primal pattern trying to reassert itself - "breaking through," as Dr. Wehr has put it, into today's "artificial world."

That theory, of course, remains to be proved. In the meantime, rather than resort to excessive medication, Americans might try to remember that though they're sleeping less, they're sleeping better and more seamlessly than humans ever have in the past. We might, on occasion, even choose to emulate our ancestors, for whom the dead of night, rather than being a source of dread, often afforded a welcome refuge from the regimen of daily life.

(A. Roger Ekirch, a professor of history at Virginia Tech, is the author of At Day's Close: Night in Times Past.)