Of course, some artificial lights were in use before Edison came around. In 1736, the city of London took a giant leap forward by installing five thousand gaslights in its streets, taming the city’s long-held fear of the dark and allowing shopkeepers to stay open past ten at night for the first time. Other cities followed as gaslights became a mark of cosmopolitan prestige. By the beginning of the Civil War, there were so many gas lamps on the streets of New York City that it was as common to venture into the night as it was during the daytime. Theaters, operas, and saloons lit by gaslights stayed open until the early morning as the newly lit streets promised a safe ride home. Homes, too, glowed from the light of flames.
Yet all of the artificial light in use around the world before Edison developed his lightbulb amounted to the brightness of a match compared to the lights of Times Square. Edison’s career as an inventor began when, as a bored teenage telegraph operator, he tried to come up with ways to send more than one message at a time on the machine. A few years later he made a name for himself by inventing the phonograph. In the first instance of what would become a defining trend of his life, Edison didn’t quite realize the popular appeal of the technical wonder he created. He saw the phonograph as a way for busy executives to dictate letters that would then be listened to and transcribed by aides. The invention became a commercially viable product only after dealers set up arcades where customers could listen to recorded music for five cents apiece. Edison had no idea that he had just unleashed the genesis of America’s mass entertainment industry, in part because he couldn’t partake in it: a hearing loss sapped his enjoyment of music.
Around this same time, French inventors installed what was known as arc light—so called because it sent currents on an arc across a gap—on the streets of Lyon. The light wasn’t anything you would want in your kitchen, unless you had a desire to burn the house down. Arc light was a barely controlled ball of current, closer to the intense, white light from a welder’s torch than the soft glow of the bulb in your refrigerator. The contraption generated plenty of light, but it wasn’t pretty. In Indiana, four arc lights installed on top of a city’s courthouse were said to be bright enough to illuminate cows five miles away. The town of San Jose, California, built a twenty-story tower and put arc lights on it. Confused birds crashed into it and eventually made their way to the tables of the city’s restaurants.
Armed with a little fame and money from the phonograph, Edison set off to invent a better form of artificial light than the arc lamp. His goal was to domesticate light, making it simple enough that a child could operate it and safe enough that accidentally leaving it on all night wouldn’t start a fire. He designed a lightbulb that glowed from electric currents passing through a horseshoe-shaped wire set in a vacuum, which essentially kept it from melting or catching on fire. His technique wasn’t necessarily the smartest or the best of the approaches to lightbulbs at the time, but he knew how to sell himself as part of the product. He slyly cultivated a public image as a wizard of inventions by handing out ownership stakes in his companies to reporters who made the trek out to see him at his lab in Menlo Park, New Jersey, and later wrote flattering articles. Edison made sure that everyone had an ample chance to hear his last name by inserting it into the companies he founded to back each new project. One of them, the Edison Electric Co., eventually morphed into General Electric.
Edison’s light became the standard of the world because it was cheap, safe, and just powerful enough to be comfortable. Unlike arc light, the lightbulb’s beauty was its small capacity. It wasn’t bright enough to reach cows a few miles away, but it had an even, steady glow that could illuminate a living room full of guests. Within a few years of its invention, a parade of men walked down the streets of New York wearing bulbs on their heads to demonstrate that light no longer had to come from flames.
If all that Edison did was perfect artificial light, he would have undoubtedly changed the course of sleep history. But he didn’t stop there. Not quite satisfied with remaking how we experience night, Edison also had a singular role in revolutionizing entertainment. He perfected the phonograph and later developed one of the first motion-picture cameras. Through these inventions, Edison created an utterly new experience: watching or listening to a person who wasn’t live in front of you. Paying customers could now see the performances of boxers, singers, and orchestras that were recorded, creating a democratic world of celebrity where everyone with a nickel could see or hear world-class entertainment. The best performers in the world were taken out of exhibition halls and available in the living room.
Thanks to Edison, sunset no longer meant the end of your social life; instead, it marked the beginning of it. Night shook off its last associations with fear and became the time when all the good stuff happens. Life could function just as well at eleven o’clock at night as it did at eleven in the morning, with darkness no longer getting in the way. The world responded to these extra hours of possibility by acting like college students spending their first month in a dorm. Sleep took a backseat to nightlife and other more important priorities, and it has never regained its former place. Manufacturers, too, recognized that they could double production without sacrificing quality by running shifts overnight while lightbulbs provided illumination. Within twenty years of their development in Edison’s laboratory, lightbulbs were hanging from the ceilings of assembly lines where some of the first graveyard-shift workers tried to stay awake on the job. There was no longer a need to leave the workbench idle just because the sun went down. The twenty-four-hour workforce was born.
Edison saw no problem as he watched the natural rhythms of sleep irrevocably change. For a reason that was never quite clear, he thought that sleep was bad for you. “The person who sleeps eight or ten hours a night is never fully asleep and never fully awake,” he wrote. “He has only different degrees of doze through the 24 hours.” Extra sleep—defined as anything more than the three or four hours that Edison claimed he slept each night—made a person “unhealthy and inefficient.” Edison saw his lightbulb as a form of nurture and believed that all one had to do was “put an undeveloped human being into an environment where there is artificial light and he will improve.”
Life, in his eyes, was like an assembly line where any downtime could be only wasteful. Not that Edison required less sleep than the rest of us. He napped throughout the day and night, sometimes falling asleep on a workbench in his laboratory and then claiming the next day that he had worked through the night. Visitors to his lab in Menlo Park can still see his small cot and pillow tucked away in a corner.
Combined with his lightbulb, Edison’s idea that sleep was a sign of laziness refashioned the way the world worked. Some of the earliest battles in the labor movement in the United States were over how long a night shift could last. Places that clung to their traditional sleeping schedules were quickly derided as backwaters filled with people who weren’t fit for the industrialized world.
Now, about a hundred years later, we have so much artificial light that after a 1994 earthquake knocked out the power, some residents of Los Angeles called the police to report a strange “giant, silvery cloud” in the sky above them. It was the Milky Way. They had never seen it before, and with good reason: LA is lit up at night by so many streetlights, billboards, hotels, cars, sports stadiums, parking lots, and car dealerships that airplanes can see the glow of the city from two hundred miles away. Angelenos aren’t alone. Two-thirds of the population of the United States and half of Europe live in areas where the night sky shines too brightly to see the Milky Way with the naked eye. In the United States, ninety-nine out of every hundred people live in an area that meets the standard of light pollution, which is what astronomers call it when artificial lights make the night sky more than ten times brighter than it would be naturally.
If all lights did was to make it easier to find things at night, there wouldn’t be much to get worked up about. But the sudden introduction of bright nights during hours when it should be dar
k threw a wrench into a finely choreographed system of life. Some ten thousand confused birds—which, like moths, are attracted to bright lights—die each year after slamming into glowing skyscrapers in Manhattan. More than one hundred million birds crash into brightly lit buildings every night across North America. Biologists now point to artificial light as a threat to the living environments of organisms as varied as sea turtles, frogs, and trees.
Let’s not kid ourselves: the animal that you are most concerned with is the one reading this book. Just like every other living being, you too are affected by the glow of streetlamps and skyscrapers. Electric light at night disrupts your circadian clock, the name given to the natural rhythms that the human body developed over time. When you see enough bright light at night, your brain interprets this as sunlight because it doesn’t know any better. The lux scale, a measure of the brightness of light, illustrates this point. One lux is equal to the light from a candle ten feet away. A standard 100-watt lightbulb shines at 190 lux, while the lighting in an average office building is 300 lux. The body’s clock can be reset by any lights stronger than 180 lux, meaning that the hours you spend in your office directly impact your body’s ability to fall asleep later. That’s because your body reacts to bright light the same way it does to sunshine, sending out signals to try to keep itself awake and delay the nightly maintenance of cleanup and rebuilding of cells that it does while you are asleep. Too much artificial light can stop the body from releasing melatonin, a hormone that helps regulate sleep.
Poor sleep is just one symptom of an unwound body clock. Circadian rhythms—which you will learn much more about in a later chapter—are thought to control as many as 15 percent of our genes. When those genes don’t function as they should because of the by-products of artificial light, the effects are a rogue’s gallery of health disorders. Studies have linked depression, cardiovascular disease, diabetes, obesity, and even cancer to overexposure to light at night. Researchers know this, in part, from studying nurses who have spent years working the graveyard shift. One study of 120,000 nurses found that those who worked night shifts were the most likely to develop breast cancer. Another found that nurses who worked at least three night shifts a month for fifteen years had a 35 percent greater chance of developing colon cancer. The increased disease rates could not be explained as a by-product of working in a hospital.
In one of the most intriguing studies, researchers in Israel used satellite photos to chart the level of electric light at night in 147 communities. Then, they placed the satellite photos over maps that showed the distribution of breast cancer cases. Even after controlling for population density, affluence, and other factors that can influence health, there was a significant correlation between exposure to artificial light at night and the number of women who developed the disease. If a woman lived in a place where it was bright enough outside to read a book at midnight, she had a 73 percent higher risk of developing breast cancer than a peer who lived in a neighborhood that remained dark after the sun went down. Researchers think that the increased risk is a result of lower levels of melatonin, which may affect the body’s production of estrogen.
There could be more discoveries on the horizon that show detrimental health effects caused by artificial light. Researchers are interested in how lights have made us less connected to the changing of the seasons. “We’ve deseasonalized ourselves,” Wehr, the sleep researcher, said. “We are living in an experiment that is finding out what happens if you expose humans to constant summer day lengths.”
The long glow of artificial lights and the short shrift given to sleep are now dominant parts of the global economy, forcing cultures that have long cherished a midday nap to conform to a world of work that Edison would approve of. Though midday naps are most closely linked with Spain and other Latin cultures, they were once popular throughout Europe, Africa, and Asia. Even today, most state-owned firms in China give their workers two hours for lunch. The first is used for eating and the second, for sleeping. One persistent gripe among managers of multinational corporations growing quickly in that country is that their employees put their heads down on their desk after lunch and sleep for thirty minutes or so.
And yet economics may eventually catch up to China as they have to the siesta in Spain. There, the tradition of taking a midday nap was curtailed in 2006 when the federal government reduced the customary three-hour lunch break for government employees to one hour in hopes that private businesses would follow. The idea was to keep Spaniards at their desks at the same time that the rest of Europe was in the office. Though some areas still largely close down at siesta time, what was once a hallmark of Spain’s culture has in some ways been reduced to a tourist ploy. In 2010, for instance, a shopping center in Madrid set up a bunch of blue couches and held what it called the Siesta National Championship. Anyone walking by was free to change into blue pajamas and take a nap. Contestants were rated on how long they slept and how loudly they snored. The idea was to show potential visitors that Spain was a place where it was so relaxing that anyone could fall asleep in an instant. But, coming in the middle of a financial crisis, the scheme didn’t go over so well. One British visitor fumed to the local paper: “We’re talking about the potential of a collapsing euro. We’re talking about surging debt, and people are still wanting to preserve the tradition of sleeping while the rest of the world is working?”
It was a fair point, but the idea of working without paying attention to the need for sleep results in its own form of failure. Hospitals, which should know better, are among the worst culprits. In the first part of the 2000s, professors from Harvard Medical School and Brigham and Women’s Hospital in Boston rounded up nearly twenty thousand doctors who were in their first year of residency and asked them to fill out a simple survey about their work lives. Work was pretty much all these interns did. Many had shifts that lasted thirty straight hours. Spending a hundred hours a week on the clock wasn’t unheard of. These doctors were no doubt trained professionals at the hospital, capable of performing their jobs under stress.
But once they got on the road to go home, it was a different story. The study found that interns who worked more than twenty-four straight hours were twice as likely to get in a car accident than a colleague who worked a shorter shift. The higher number of long shifts the doctors worked, the more likely they were to become a danger on the roadway. Interns who worked at least five long shifts a month were twice as likely to fall asleep while driving a moving vehicle, and three times more likely to fall asleep while stopped at a red light, than a colleague who worked fewer hours.
Employers who want or need to keep their businesses open at all times are realizing that they are have to deal with the equivalent of sleepy doctors causing accidents if they continue to expect employees to work extra-long shifts regularly. That is where Martin Moore-Ede comes in. A former professor at Harvard Medical School, Moore-Ede now runs one of the largest companies in the growing field of fatigue management. More than half of the companies in the Fortune 500, and a Super Bowl–winning team, have asked Moore-Ede’s company, Circadian, to develop working environments for their businesses that allow a worker’s body to function at high levels despite the demands of sleep and exposure to artificial light.
He spoke with me while in his office in Cambridge, Massachusetts. With glasses perched on his nose and a receding hairline that hints at his age, Moore-Ede looked very much like the former professor that he is. The last year had been very good for him. His company had expanded, and had offices in Australia, Japan, the United Kingdom, the Netherlands, and Germany. His client list included Exxon-Mobil, Chevron, and American Airlines. The blue-chip companies of the world were paying him sums of money that he would only call “not inexpensive” to train their multinational workforces. More business was coming, thanks to government regulations in the United States and the United Kingdom that took effect in 2010 and required businesses in certain fields to have a fatigue management policy in place. Similar rules were alread
y in place in Australia, Canada, and parts of Europe.
Solving the problem of sleep-deprived employees entails a lot more than giving a tired worker a pillow and a place to lie down, though that would certainly help. Fatigue management is one of those lines of work, like running a hotel, that sounds very easy until you try to do it yourself. Because of how the body’s clock works and how the brain reacts to artificial light, expecting someone to sleep soundly at any time of day or night isn’t always possible. The chief reason is that, unlike teenage bodies, adult bodies are not built to sleep past noon. A study by researchers in Sweden found that even in ideal sleeping conditions, subjects who would normally sleep eight hours if they went to bed at eleven o’clock at night tend to sleep only six hours if they wait until three in the morning to fall asleep. Timing trumps being tired. Even making a person exhausted beforehand doesn’t change the body’s awareness of the clock. In one study, subjects were kept up all night and only allowed to go to sleep at eleven in the morning. Most slept for just four hours. Though exhausted, their bodies wouldn’t let them stay in dreamland.
Moore-Ede’s job often boils down to challenging conceptions about the workplace that haven’t been updated since Edison’s time. Sometimes that leads to arguments with employers who can’t accept that letting workers sleep while on the clock can be a productive use of time. “The railroad industry almost threw me out of the room when I suggested that engineers should take a brief nap rather than have to stay up continuously,” he told me with obvious pride in his voice.
But more often than not, he uses numbers to speak to businesspeople in the language they understand: money. He discovered that one transportation company was paying out $32,000 in accident costs per every million miles its workers and equipment traveled. The company clocked hundreds of millions of miles a year, which made these costs far from trivial. Moore-Ede developed a staffing model that restricted long work shifts and required workers to pass awareness tests to prove that they weren’t in danger of falling asleep on the job. Within months, accident costs plummeted to only $8,000 per million miles. Overall, the company’s return on its investment was greater than ten to one.
Dreamland: Adventures in the Strange Science of Sleep Page 3