Slumber's Unexplored Landscape - comparatively little research on sleep has been conducted

Science News, Sept 25, 1999 by Bruce Bower

People in traditional societies sleep in eye-opening ways

Ah, the sweet simplicity of sleep. You tramp into your bedroom with sagging eyelids and stifle a yawn. After disrobing, you douse the lights and climb into bed. Maybe a little reading or television massages the nerves, loosening them up for slumber's velvet fingers. In a while, you nod off. Suddenly, an alarm clock's shrill blast breaks up the dozefest as the sun pokes over the horizon. You feel a bit drowsy but shake it off and face the new day. Images of a dream dissolve like sugar in the morning's first cup of coffee.

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There's a surprising twist, however, at the heart of this familiar ritual. It simply doesn't apply to people currently living outside of the modern Western world--or even to inhabitants of Western Europe as recently as 200 years ago.

In such contexts, and probably throughout human evolution, solitary shut-eye organized around a regular bedtime and a single bout of sleep proves about as common as stock car racing or teleconferencing. Surprisingly, anthropologists have rarely scrutinized the sleep patterns and practices of different cultures, much less those of different classes and ethnic groups in the United States.

An initial attempt to draw back the veils of sleep in hunter-gatherer groups and other traditional societies has uncovered a wide variety of sleep customs, reports anthropologist Carol M. Worthman of Emory University in Atlanta. None of these snooze styles, however, looks anything like what modern Western folk take for granted.

This finding raises profound questions for the burgeoning discipline of sleep research, Worthman says. Over the past 50 years, scientists have avidly delved into slumber's biology. Early research identified periods of rapid-eye-movement (REM) sleep, during which intense dreams often occur. Current efforts pursue genes involved in wakefulness and sleeping (SN: 8/14/99, p. 100). Researchers have also taken strides toward treating insomnia and other sleep disturbances.

While investigators readily concede that they don't yet know why people sleep and dream, they assume that they at least know how people should sleep: alone or with a partner for a solid chunk of the night. Sleep studies therefore take place in laboratories where individuals catch winks while hooked up to a bevy of brain and body monitors.

However, the distinctive sleep styles of non-Western groups may mold sleep's biology in ways undreamed of in sleep labs, Worthman suggests. They may influence factors ranging from sleep-related genes to the brain's electrical output during various sleep phases.

"It's time for scientists to get out into natural sleep environments," Worthman remarks. "It's embarrassing that anthropologists haven't done this, and the lack of such work is impeding sleep research."

A seemingly innocent question awakened Worthman to her discipline's ignorance of how people sleep. In 1994, she had a conversation with pediatrician Ronald E. Dahl of the University of Pittsburgh School of Medicine, who studies the effects of mood disorders on sleep. He asked the Emory scientist to tell him what anthropologists know about the history and prehistory of sleep. "[My] bald, if somewhat overstated, answer was `zero,'" she says.

Sleep scarcely figures in the literature on either cross-cultural differences or human evolution, Worthman realized. Investigators generally relegate slumber to the sidelines, treating it as a biological given with little potential for variation from one place to another, she holds.

A few researchers have bucked this trend. For instance, anthropologist James J. McKenna of the University of Notre Dame in Indiana has reported that babies in many countries outside the United States sleep next to or in the same room as their parents. Contact with a parent's body helps regulate an infant's breathing and other physiological functions, he asserts, perhaps lowering the risk for sudden infant death syndrome (SN: 12/4/93, p. 380).

McKenna's work should have roused investigators of traditional societies out of their sleep-related torpor, Worthman says. Yet, even seasoned field-workers have tended to ignore sleep--at least in their published works--while describing food production, sexual practices, and other facets of daily life.

So, Worthman contacted seven researchers who she knew had intimate knowledge of one or more traditional societies, including nomadic foragers, herders, and village-based farmers. Among these far-flung populations, none of the investigators, by their own admission, had systematically studied how people sleep. After plumbing what the researchers had absorbed about nighttime activities, Worthman has assembled a preliminary picture of sleep practices in 10 non-Western populations.

Worthman's findings rip the covers off any lingering suspicions that people everywhere sleep pretty much alike. Far from the wallpapered confines of middle-class bedrooms, sleep typically unfolds in shared spaces that feature constant background noise emanating from other sleepers, various domestic animals, fires maintained for warmth and protection from predators, and other people's nearby nighttime activities.

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Slumber's Unexplored Landscape - comparatively little research on sleep has been conducted

Science News, Sept 25, 1999 by Bruce Bower

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