Brilliant

by Jane Brox

  Divided sleep, Ekirch notes, began to slip away as artificial light increased. By the seventeenth century, the wealthy, who already prized their nightlife, no longer experienced it. Later, as the middle class acquired increased light, divided sleep slipped from them as well. Then laborers lost it, though vestiges of it remained even into the late nineteenth century. Robert Louis Stevenson, who sometimes slept in the open during his journey through the Cévennes in southern France, observed that a wakeful period in the middle of the night was a natural occurrence not only in people still living close to nature but in all of nature:

  There is one stirring hour unknown to those who dwell in houses, when a wakeful influence goes abroad over the sleeping hemisphere, and all the outdoor world are on their feet. It is then that the cock first crows, not this time to announce the dawn, but like a cheerful watchman speeding the course of night. Cattle awake on the meadows; sheep break their fast on dewy hillsides, and change to a new lair among the ferns; and houseless men, who have lain down with the fowls, open their dim eyes and behold the beauty of the night.... At what inaudible summons, at what gentle touch of Nature are all these sleepers thus recalled in the same hour to life?...Even shepherds and old country-folk, who are deepest read in these arcana, have not a guess as to the means or purpose of this nightly resurrection. Towards two in the morning they declare the thing takes place.

  Given a chance, many humans will fall back into that medieval pattern of sleep, which may have been the way even the first humans slept. When Dr. Thomas Wehr and researchers at the National Institute of Mental Health attempted to replicate prehistoric sleep conditions by imposing on a group of men a daylight time of ten hours—what people in the middle latitudes during the dead of winter experience—he found that they

  slept only about an hour more than normal, but the slumber was spread over about a 12-hour period. They slept for about four to five hours early on, and another four to five hours or so toward morning, the two sleep bouts separated by several hours of quiet, distinctly nonanxious wakefulness in the middle of the night. The early evening sleep was primarily deep, slow-wave sleep and the morning episode consisted largely of REM, or rapid eye movement, sleep characterized by vivid dreams. The wakeful period, brain wave measurement indicated, resembled a state of meditation.

  "We think Thomas Edison had a bigger effect on the human body clock than anyone realized," remarked Dr. Czeisler. Edison, who favored catnaps on his laboratory tables, would have loved to think so, for he once commented, "Everything which decreases the sum total of man's sleep, increases the sum total of man's capabilities. There is really no reason why men should go to bed at all." Few would now agree with Edison, for although we may not yet know why we need to sleep, most people now understand it to be essential. As researchers look more deeply into sleep, they increasingly discover the true toll its lack takes on the physiological and psychological well-being of humans. Sleep-deprived people are more prone to elevated blood pressure and blood glucose levels. Lack of sleep depresses the immune system, affects memory and brain function, and shifts levels of the hormone leptin, which controls appetite, so it may also contribute to obesity.

  We humans can alleviate the way artificial light creates havoc with our biological clocks: sleep institutes, sleep programs, sleep doctors all prescribe a regimen that re-creates ancient life. In addition to advising insomniacs to get daily exercise, avoid stimulants, and slow down in the evening, experts suggest that they avoid bright light at night, go to bed in a dark room, and sleep until daylight. But other creatures adversely affected by our light can do little more than suffer its effects or adapt to it. Nocturnal animals hunting in the dark, as well as those abroad in daylight that sleep at night—standing up, or with one eye open, or in hiding—are at its mercy, and human light not only affects their circadian rhythms; it can also compromise their chances for survival and even alter their evolutionary trajectories.

  As with humans, the effects of ubiquitous light on wildlife aren't always easy to isolate, since accompanying them are countless other environmental changes and losses to habitat. Buildings and roads disrupt forage routes; noise and activity compromise many animals' ability to hunt; human endeavors create new ecosystems in which artificial light plays only a part. According to William A. Montevecchi, "Offshore hydrocarbon platforms develop rapidly into artificial reefs that create marine communities. These reefs attract, concentrate and proliferate flora, crustaceans, fishes, and squids.... Lighting attracts invertebrates, fishes, and birds, and organisms at higher trophic levels are in turn attracted to lower ones as well as to the lighting."

  But light alone also changes everything. For many nocturnal animals, night is a negotiation between hiding and seeing. Mammals prefer to stay in the shadows and tend to avoid the full moon, which exposes them and makes them vulnerable to predators. Artificial light not only makes it more difficult for animals to hide; it also makes it more difficult for mammals that depend on keen night vision for both food and safety to see:

  Many nocturnal species are using only the rod system, and bright lighting saturates their retinas. Although many ... have a rudimentary cone system and can switch over to it within a couple of seconds, during those seconds they are blinded. Once they switch to the cone system, areas illuminated to lower levels become black, and the animal may become disoriented, unable to see the dark area...[ahead] and unwilling to flee into the unseeable shadows whence it came.... Finally, if the animal is in the lighted area long enough to saturate its rod system, it will be at a distinct disadvantage for 10–40 minutes after returning to darkness.

  Light also changes the way nocturnal animals negotiate their world. A road lined with streetlights creates a kind of visual barrier: an animal cannot see beyond the lights and must take extra time, caution, and effort to make its way. One scientist, in studying the habits of pumas in southern California, observed that when a puma was "exploring new habitat for the first time, [it] stopped during the night at a lighted highway crossing its direction of travel.... In several instances, the animal would bed down until dawn, selecting a location where it could see the terrain beyond the highway after sunrise. The next evening, the puma would attempt to cross the road if wildland lay beyond or would turn back if industrial land lay beyond."

  No less essential for creatures than the dark is the natural light of the night. Since light travels in straight lines, birds and mammals use celestial light for both navigation and orientation. When human light intrudes, it can misinform and confuse them. Consider the consequences of artificial light on birds. For centuries, nocturnal flyers have been drawn to lighthouses. Back when the Eddystone lighthouse keepers were eating their candles, the small light probably wasn't much bother. But a 1912 illustration shows the Eddystone lighthouse clouded by flocks of birds, milling and confused, streaming skyward, circling the white stone tower. In modern times, the dangers are multiplied: birds are drawn to the myriad illuminated windows of tall buildings and skyscrapers, and to the lights on broadcast and communication towers, which they either crash into or circle until they are exhausted. Birds also congregate around the flares on offshore oil and gas plat forms, especially "on misty and foggy nights, and as they fly near and through the flames they are burned to death." And not just elevated lights cause problems: water birds and marsh birds can mistake light-reflecting surfaces for water, and once they land on dry ground, they can't easily take off again. While they struggle to fly away, they remain exposed and vulnerable. And nocturnal seabirds that hunt for bioluminescent prey are mistakenly attracted to lights and confused by them; as a result, their search for food is frustrated. In all cases, if birds that are trapped by light manage to escape death, they've expended precious energy they can't afford to waste. For those in migration, their confusion often delays their arrival at breeding or wintering grounds.

  It is not only light itself but the duration of the light that affects birds. They, too, are exhausted by sixteen-hour days. Artificial light trigger
s their dawn response and leads them to sing after sunset, sometimes to sing all night. The artificially extended day affects their migration and breeding patterns as well.

  In the animal world, even what goes on under one streetlight after dark has complex and far-reaching consequences, for a single light is capable of changing the equilibrium of an ecosystem. Moths and insects gather around a streetlight; bats and toads come in to pick at easy prey. Notes one scientist, "The habit of feeding at artificial lights is now so common and widespread among bats that it must be considered part of the normal life habitat of many species." This not only increases the stress on insect populations; it also changes the relations between different bat species, since not all species use lights for feeding, though they may feed on similar insects. The presence of streetlights gives species that use lights a competitive advantage over other species. The non-light-using species may decline because they have lost their competitive edge. By altering habitat and spurring adaptations that might eventually become encoded in the future lives of insects, mammals, birds, and reptiles, "humans are changing the evolutionary trajectories of those affected species, causing them to adapt to new sets of conditions," notes biologist Bryant Buchanan. "Simply conserving species richness or population sizes does not conserve the evolutionary and behavioral diversity contained in those taxa."

  Sometimes artificial light becomes an evolutionary trap as the age-old biological imperatives of a species, which helped it survive for eons, turn into liabilities. The most well-known example of such a trap is the predicament of the loggerhead turtle, which can live for more than 130 years. It inhabited coastal waters long before humans existed on earth, trolling the shallows, feeding on sand dollars, whelks, and conchs. The female, year after year, crawls out of the surf and onto sand beaches to nest. She has always preferred the cover of darkness for safety, and now the bright lights of shoreside developments often drive her away from prime nesting sites. When she does settle on a nesting place, she digs a pit along a sandy shore with her flippers, then deposits a clutch of eggs, falling, "as they have fallen for a hundred million years," writes David Ehrenfeld, "with the same slow cadence, always shielded from the rain or stars by the same massive bulk with the beaked head and the same large, myopic eyes rimmed with crusts of sand washed out by tears."

  She then covers the nest and returns to the sea. The eggs take months to develop, during which time, if the female has not been able to nest in the best of places, they are all the more vulnerable to extreme high tides, storms, and predators. If they survive their incubation period, the hatchlings then extricate themselves and dig their way—en masse—to the surface. If the surface sand is hot, they know it to be daylight, and they burrow back down and wait until the sand cools after sunset. Then they begin their trek to the sea. They are keyed to move toward the lightest horizon, and for thousands of years this meant they crawled away from dark dunes and vegetation and toward the ocean, whose surface, glinting and sparkling with reflecting starlight and moonlight, was brighter than the interior land. In a dark landscape, the baby turtles usually have no more than a two-minute trip to the beach.

  But on developed beachsides, lit with condominiums, streetlights, and commercial districts, the turtles are confused by the brilliance of the built landscape at night. They crawl toward high land instead of the sea; crawl into roadways, where they are killed by cars; or crawl so far that they die of exhaustion. If they manage to reorient themselves and somehow reach the water, their mortality rate—already considerable, for they have to breach a surf rife with predators and then swim for at least a full day to reach their dwelling grounds—is much higher.

  Amid the brilliance, it seems almost nothing remains unaltered by light. It affects the foraging and schooling patterns of fish and the timing of migrations. It alters the drift stream of insects on water and the vertical migration of zooplankton and fish. It diminishes the effectiveness of bioluminescent creatures. Fireflies were once bright enough to light up a village night. Now human light washes out their glow, which makes it harder for them to attract mates. And plant life is not immune. Measured light and darkness signal plants that the right pollinators are available and that competition is minimal. The coarse and prickly cocklebur (Xanthium pensylvanicum) —thriving in vacant lots and dumps, catching on clothes, riding on fur—flowers nevertheless and is keyed to its optimum bloom time by the length of the night. But the dark needs to be continuous: "A light break as short as one minute in the middle of a long night would prevent [it] from flowering."

  Even when our lights are meant to be their most heartening and consoling, they have consequences for wildlife. In 2004, during the annual Towers of Light tribute to commemorate those killed on September 11, 2001, spectators in New York City wondered at "the thousands of little stars ... suspended in the air." It was a calm, moonless night during the fall migration. The upward flow of warm air in the columns of light induced moths to circle in the lights for fifteen stories or more, and thousands of birds, also drawn to the columns, circled above the moths. Few people understood what they were seeing. "Some people thought they were specks of dust," reported the New York Times. Others, perhaps remembering the rain of debris on that clear day three years before, concluded otherwise: "Some people saw ashes. Some thought there were fireworks in the light columns. Some saw spirits."

  What they could not see, of course, were the actual stars, most of which were obliterated by the brilliance of the city night.

  20. More Is Less

  At the second match the wick caught flame. The light was both livid and shifting; but it cut me off from the universe, and doubled the darkness of the surrounding night.

  —ROBERT LOUIS STEVENSON,

  Travels with a Donkey in the Cevennes

  DURING THE LATE NINETEENTH CENTURY, Vincent van Gogh saw countless subtleties in the dark skies of southern France: "One night I went for a walk by the sea along the empty shore," he wrote to his brother, Theo, in 1888. "The deep blue sky was flecked with clouds of a deeper blue than the fundamental blue of intense cobalt, and others of a clearer blue, like the blue whiteness of the Milky Way. In the blue depth the stars were sparkling, greenish, yellow, white, pink, more brilliant, more sparklingly gemlike than at home—even in Paris: opals you might call them, emeralds, lapis lazuli, rubies, sapphires." As van Gogh—aided by gaslight—painted that sky, he also painted myriad relations between the celestial and the human. In Starry Night, the illuminated village appears intimate—and inconsequential—against the roil of stars and the quarter moon above it, while in Starry Night over the Rhône, the human light and starlight are in conversation with each other: a couple stand at the lower right of the painting, and all around them the world is alive with light. Just beyond them, the river is ribboned with the reflection of the streetlights of Arles in the distance. And beyond the river, the town itself spangles the horizon. But it isn't too bright to stop the stars overhead or the sense of night as enormous and other. The night sky, defined by the brilliance of the stars, occupies almost half of the canvas.

  Even in the midst of Arles, in The Café Terrace on the Place du Forum, Arles, at Night, human life negotiates a middle distance between the cobbled street and the stars. The glow of gaslight washes the walls of the café and its canopy roof; here and there a private, ruddy luminescence shines from second- and third-floor windows, and a few shop windows glow. But beyond the terrace, the dark increases quickly, and stars glitter in the gaps between buildings. Present-day astrophysicist Charles Whitney suggests that van Gogh "has overpopulated the small patch of sky in view of the interference that might be expected from the café lights." And van Gogh himself once insisted, "I should be desperate if my figures were correct. ...I do not want them to be academically correct.... My great longing is to learn to make those very incorrectnesses, those deviations, remodelings, changes in reality, so that they may become yes, lies if you like—but truer than the literal truth." You can imagine, in the truth of his time, that even in
the midst of nightlife, contemplation of the stars was part of being at home in the world, a counterpart to earthly life.

  For many people, light pollution is now so pervasive that it obliterates any chance they may have to observe the night sky. In particular, sky glow—the orangey brightness in the air around cities, towns, and industrial sites that fades to purple in the upper night sky—hinders our seeing. Although sunlight reflecting off the moon, earth, and cosmic dust, and starlight scattering through the atmosphere, make for some natural sky glow, the ubiquitous light shed from homes, businesses, and streetlamps causes most of it. In the twenty-first century, even many wide suburban backyard views of the heavens have shrunk to a sprinkling of dim stars, and most people in the developed world see the night sky as if it is always washed in moonlight, at least as bright as a first-quarter moon. To people in large modern cities, the night sky always appears brighter than on nights near the full moon in the countryside, and the Milky Way—that bridge across the sky of dust and stars and gas, "brilliant with its own brightness," Ovid once wrote—can't be seen with the naked eye by two-thirds of Americans and half of all Europeans.

  The Milky Way had always been the stuff of legend, variously called the Deer Jump, the Silver River, the Straw Thief's Way, the Way of the Birds, the Way of the White Elephant, the Winter Way, and the Heavenly Nile. It guided pilgrims at night and so was known also as the River of Heaven, the Road to Santiago, and the Roman Road. Now its appearance has become so unfamiliar that when the lights went out in Los Angeles during a 1994 earthquake, "emergency organizations as well as observatories and radio stations in the L.A. area received hundreds of calls from people wondering whether the sudden brightening of the stars and the appearance of a 'silver cloud' (the Milky Way) had caused the quake."