The Mystery of Sleep: Why a Good Night's Rest Is Vital to a Better, Healthier Life


A World That Never Sleeps


THE MYSTERY. Have humans changed since we conquered the night? Since the invention of the lightbulb, the world never sleeps, but nighttime, irregular-shift, and overtime jobs can contribute to sleep deprivation and health problems.

The Case of the Sleepy Bus Driver

Some of the patients who come to see me at the sleep clinic have complaints that must be addressed immediately. Aircraft pilots, air traffic controllers, ship captains, bus drivers, long-haul truckers, medical personnel, and others whose jobs leave no room for error caused by nodding off constitute emergency cases.

One morning I was consulted by a woman in her early thirties who worked as a public transit bus driver. She was experiencing severe daytime sleepiness and finding it difficult to stay awake on the job. After her supervisor had witnessed her nodding off on a few occasions and threatened disciplinary action, she sought help. We needed to evaluate her to determine whether she had a disease that was making her sleepy and therefore jeopardizing her ability to drive a public bus safely.

To diagnose the problem, I began by asking her the usual medical questions to see whether she had the symptoms of the major sleep disorders, such as sleep apnea, narcolepsy, and severe insomnia, that normally cause excessive sleepiness. She did not. Then I asked her about other possible medical conditions, including thyroid disease and diabetes, which might be associated with her sleepiness. She had no symptoms of those maladies either. But once she started to describe her daily schedule, I knew I’d found the cause of her sleep problem. She didn’t have a disease that was making her sleepy and impeding her ability to do her job; it was the job itself that was making her sleepy and thus a danger to the public.

The Graveyard Shift Can Be Hazardous to Your Health

What if you knew that something you were doing might increase your risk for any or all of the following: breast cancer, abnormal menstrual cycles, obesity, abnormal blood lipids, cardiovascular disease? You would want to know what it was, and you would probably want to do something about it. Well, studies have shown that working night shifts puts workers at greater risk than doing day shifts; in fact, links between work schedules and health risks are becoming more and more clear.

Many studies have demonstrated possible connections between shift work and health problems such as cancer. A study from Finland in 2008 found that men working night shift were more likely to develop non-Hodgkin lymphoma, a malignancy involving lymph nodes, than those not working night shift. A study from the Fred Hutchinson Cancer Research Center in Seattle in 2001 reported that women working the graveyard shift (midnight to morning) had a 60 percent higher incidence of breast cancer than those not working this shift. A 1996 study of Norwegian radio and telegraph operators showed that late-shift workers had a 50 percent higher incidence of breast cancer than non-shift workers. A study published in 2012 from the Danish Cancer Society showed that shift work may increase the risk for breast cancer and that the largest risk is associated with the most disruptive shifts (either regular night shifts or rotating night and day shifts). Denmark has awarded compensation to shift workers who have developed breast cancer. And research published in 2016 showed that working at night can increase the risk of estrogen-receptor subtypes of breast cancer, especially in premenopausal women.

A 2011 study from Taipei showed that women working on a rotating shift schedule in semiconductor manufacturing plants were less likely to become pregnant than those on regular shifts and that those who became pregnant were more likely to have smaller babies.

Rotating and night-shift work can also increase the risk of cardiovascular disease compared to day-shift work. A French group examining a decade of scientific studies concluded in 2011 that shift work seemed to affect blood pressure and lipid profile. A 2011 study from Japan reported that the circulation to the heart was impaired in nurses on night shifts. Another, published in 2014, showed that those working night shifts were more likely than those not working nights to develop metabolic syndrome (obesity, hypertension, diabetes), which is linked to heart disease. A 2016 Danish study reported an increased risk of diabetes in nurses who worked the night shift compared to the day shift.

Despite the extant studies, scientists have much to learn about the connections between night-shift work and health. Why, for example, do night shifts increase risks of breast cancer? The connection might lie in the body’s timing of hormone secretion. Some hormones, such as melatonin, are secreted primarily during sleep, and recent studies have suggested that melatonin might inhibit certain cancers. A 2016 study from China showed that melatonin levels were lower in women with ovarian cancer compared to healthy women. A person who works at night is exposed to more light than someone who works during the day, and this increased exposure might lead to a reduction in melatonin production. Almost all the cells of the body contain circadian clocks. Our bodies also contain cells called natural killer (NK) cells that kill cancer cells. Studies in 2012 from Rutgers University have shown that disrupting the circadian clock of the NK cells promotes lung cancer growth in experimental animals. All cells contain clock genes and have a circadian rhythm. In 2016, research from Poland found abnormalities of the genes controlling the cell clock of aggressive breast cancer tumors and those lacking estrogen receptors. The graveyard shift may be literally killing workers—and others.

Is Your Pilot Awake? How About Your Doctor?

In today’s world, certain jobs carry risks not only to the workers but to all the people their work brings them in contact with. Airline pilots, truck drivers, train operators, bus drivers, and others in the transportation industry; doctors, nurses, anesthesiologists, and others in the health care industry all perform jobs with life-or-death consequences. We put our lives in their hands. We need them to be awake and alert. But the 2012 National Sleep Foundation poll found that most workers in the transportation industries did not get enough sleep. Airline pilots, in particular, drank large amounts of caffeine and took naps to counteract their frequent sleepiness, and they admitted to having made serious errors due to sleepiness. In addition to schedules with long work hours, airline pilots must deal with jet lag, which puts them at greater risk for sleep problems.

No one wants an airline pilot with droopy eyelids. Nor is it pleasant to think that the air traffic controller might be unable to concentrate because he or she is coming off a twenty-four-hour shift. Thousands of jobs require alertness, but workers in the transportation industry have a special need to stay awake. The consequences of their drowsiness can be disastrous. Most transportation industries now have rules about how many hours a person can work and how much time he or she must take off for rest before working again.

Medical personnel are also in the risk business, and sleep deprivation can be a big problem for them as well. A 2011 study from Israel showed that medical residents were more likely to fall asleep while driving or to have automobile accidents after working the night shift. You do not want to be on the road when a sleepy medical resident is heading home from the night shift. Nor do you want a doctor who is unable to focus because she or he spent the entire night in the operating room before your appointment. In the past few years, the ACGME (Accreditation Council of Graduate Medical Education), the organization that accredits medical intern, residency, and fellowship programs, has put in place regulations controlling the number of hours that an intern or resident can work. When I was an intern and then a medical resident, a hundred-hour or more workweek was the norm. Now, interns and residents in hospitals cannot work more than eighty hours a week. A report from Harvard University in 2010 concluded that reducing or eliminating medical resident work shifts of more than sixteen hours resulted in improvements in patient safety and resident quality of life. A report from Stanford University in 2016 showed that patients taken care of by interns and residents who worked more than eighty hours weekly (compared to those working fewer than eighty hours) stayed in hospital longer and were more likely to be transferred to an intensive care unit. At the same time, some controversy remains about whether the eighty-hour-a-week restriction is good or bad since it means there is less continuity of care (the doctors change shifts more often) and less education of the residents (who would spend less time in hospital and thus learn less from their patient experience).

The All-Nighter as a Way of Life

If this book had been written 150 years ago, this chapter probably would not have been necessary. No one had electric lights or telephones, and people worked when it was light and went to bed when it got dark because there was not much else they could do. (It was even difficult to read because it had to be done either by gas lamp or candlelight.) On average, North Americans slept at least an hour more each night than they do today.

Electric light changed all that. In October 1878, Thomas Edison applied for a patent for the electric lightbulb; it was approved in April 1879. The first public demonstration of the lightbulb took place on the last day of 1879. In 1882 the first Americans lost sleep because of electric lights when one square mile of New York City received electric power; there were only fifty-two customers on the first day. But electric utilities soon sprang up all over the country. Electricity came to the White House while Benjamin Harrison was in office (1889–93). In 1892 General Electric, now one of the world’s largest companies, was formed, first to generate power and later to produce lightbulbs. By the mid-1930s about 90 percent of urban America and 10 percent of rural America had electricity. Within a decade almost everybody in America had it. Now most of the world’s population has access to electricity. The night has been conquered, and the world will never be the same. Electricity and later advances in technology have spurred several trends in the way we conduct our work and social lives, some of which can be contributors to sleep deprivation.


New York may be the city that never sleeps, but when it comes to work, the whole world never sleeps; in virtually every city of the world there are many people who are working all night in jobs that did not exist in the nineteenth century. Large hospitals never close. Some factories never close. Media outlets (television, print, internet) operate twenty-four hours a day.

In the twentieth century, as electricity and artificial lighting became available, industrialists decided that it would be more productive to keep factories and machinery running round the clock, so they added two extra shifts to each workday. In 1922 Henry Ford introduced the twenty-four-hour assembly line. Every major industry soon adopted his model as a way to increase market share and improve productivity.

The number of industries that never shut down increased; today it is staggering. Because people were now awake, working, and going to and from their homes in the middle of the night, all-night businesses sprang up to service them, including radio and later television stations, grocery stores, and gas stations, as well as all companies to service those businesses, such as the companies that deliver goods to these companies, and companies that offer computer and network tech support. In the twenty-first century, call centers and, later, websites were created to enable customers to make reservations for an airline, find tech support for their computers or dishwashers, or trade on the international commodities market at almost any hour of the day or night. These call centers and industries employ millions of people worldwide, which means that millions of jobs now require their employees to work during the hours normally reserved for sleeping. These working hours can play havoc with the body clock, family life, and, as we have seen, even the workers’ health.


During the world wars women were not allowed to serve in the theaters of war, but they were employed to do the work needed to keep nations running and armaments coming. In addition to more traditional female jobs such as nursing, women now worked in factories, on farms, and in administrative jobs. After the wars ended, many women sought to continue working at these jobs. In the past century women have made enormous strides in the workplace, taking on all the jobs that men do. This includes the high-risk jobs that require special alertness. Women are now long-haul truck drivers, airline pilots, surgeons, police officers, soldiers, and firefighters.

Yet in spite of the strides women have made in the professional world of careers, in most families worldwide, it is the woman who deals with the majority of family and household tasks. Women still are usually the ones who keep track of their family’s health issues, know the shoe sizes of their children, schedule the children’s after-school lessons and activities. Women still stay up late at night making the children’s lunches and cleaning the kitchen. Although more and more men are taking on these roles, and many families have a single male parent as head of the household, women still take on a disproportionate amount of family care. The number of women in charge of single-parent households in the United States is at least four times greater than that of men, for example. Many women are thus working two jobs: a daytime professional job, and a night and weekend job keeping the household going.


Children today have activities available to them that were almost never available to previous generations. When I was growing up, the only after-school activities available to most children were piano lessons and a few afternoon clubs at school. Now some children have access to activities ranging from rhythmic gymnastics to martial arts, debating, chess, and dozens of other hobbies. They take lessons such as ballet, acting, and skating. Even appointments with doctors, dentists, and orthodontists can eat into a child’s day. Trying to cram a variety of activities into a twenty-four-hour day can lead to sleep deprivation. Consider ice hockey. If a child is on an ice hockey team, chances are that he or she has played many games that began at 6:00 A.M. because this is when ice time is available. The entire family might leave home at 4:00 or 5:00, in the dark, to take the child to the game. As we have seen, children need on average more sleep than adults, but in today’s busy world they are not getting it.


The result of these trends is that today’s North Americans are overworking, and the more they work, the less they sleep and the worse they feel—and the more likely they are to get sick. A study published in 2003 concerning sleep and health among nurses found that of 71,000 nurses, those sleeping fewer than five hours were 45 percent more likely than those sleeping eight hours to develop a cardiac disease after ten years. The link between sleep and health was also shown in the 2002 National Sleep Foundation Sleep in America poll. This poll of 1,010 adults age eighteen and older found that the less people slept the more likely they were to feel poorly. People sleeping more than six hours on a weekday were more likely to feel optimistic and satisfied with life, while those getting fewer than six hours were more often tired, stressed, sad, or angry.

The same poll found that just over 50 percent of U.S. adults admitted to having driven a motor vehicle while being drowsy in the previous year. Males were much more likely than females to admit to drowsy driving, as were young adults (age eighteen to twenty-nine) and adults with children in the home. Twenty-two percent of males and 12 percent of females admitted to having fallen asleep at the wheel in the previous year!

Today’s world is obsessed with speed, communications, productivity, and global competition, and the situation is unlikely to change any time soon. If anything, these trends are getting worse. I have colleagues who spend two to four hours a day commuting to and from work. Even though many of them do their driving in fancy, comfortable cars, math wins the day. A person who spends two hours a day driving to and from work, and works forty-eight weeks a year, spends 480 hours on the road in one year. Some people avoid rush-hour traffic by leaving their homes between 4:30 and 6:00 A.M. and leaving work after 6:00 P.M. In consequence, they hardly ever see their children. They might never see their families in the mornings, and they have only a short time with them in the evenings because they need to go to bed by about 9:00.

So even when people’s schedules don’t make them sick, the twenty-four-hour workday is affecting their quality of life. But although they cannot change the world, people can manage their work lives to improve their quality of life.

Taking Control of Sleep Time—and Improving the Quality of Life—in Today’s Busy World

People have many priorities. In today’s world, financial needs (paying the rent or mortgage, finding a job, any job) often take priority over quality of life and health and family. But people whose lives are adversely affected by their work schedule can do something about it. They can start by making a realistic inventory of their values and priorities, then chucking the items that are less important. Once the list has been narrowed down to the two or three most important values, they need to consider whether their lifestyle supports those values. Are they spending time on their priorities? If someone’s most important value is to spend time with the children but his or her schedule makes this virtually impossible, then that person will need to change the schedule. If spending two to three hours a day in a car or working night or other disruptive shifts does not allow someone to do the things that matter most, then he or she needs to find a job that does. If a work schedule leaves someone tired and irritable or is affecting his or her health, it is time to consider changing the schedule or finding a new career. This may be very difficult. (I have used this approach many times with people in their forties who have sleep problems that are related to severe obesity. I remind them that if they remain morbidly obese, and have a severe untreated sleep disorder, they are unlikely to be alive for their children’s high school graduation and probably will not live to see any grandchildren. If this is important to them, they need to address the problem and develop a plan to lose weight and treat the sleep disorder.)


An important factor that many people need to consider is whether to take or keep a job with night or irregular shifts. Shift workers need to address the question of how to get the right amount of sleep to keep them healthy, avoid putting themselves or others in danger, and enjoy a productive work and home life. The first step is determining whether their body clocks can adjust to shift work. Remember that people who stay awake nights are generally battling their body clock, which is telling them to go to sleep. It is as though they are subjecting themselves to jet lag every few days. Night owls, on the other hand, are more naturally inclined to do shift work. Their bodies want to stay awake at night. People with late body clocks frequently discover that working night shifts makes a good fit with their life needs. Some people’s body clocks even allow them to work rotating or changing shifts without difficulty.

But those for whom staying up late or working at night is ruining their life need to decide whether the advantages of shift work (having a job, earning extra pay) are worth the tradeoff. For instance, the morning host of a radio station in a huge American market used to have to get up at 4:00 A.M. After years of going to bed at 8:30 in the evening and getting up while it was still pitch dark, he decided that his prestigious, well-paying job was not worth the cost. He is much happier now with a less prestigious job with normal hours.

People considering shift work should try to find out what type will work best for them. A fixed shift is one with a regular schedule in which the person always works at the same times. For example, someone might work five nights in a row from midnight to 8:00, have two days off, then work another five nights, and so on. A rotating shift is one in which a person works a few days at one shift, has a few days off, and then switches to another shift. The number of days he or she works in each shift can vary, and the direction of the shifts can vary. One schedule might call for working four nights in a row, then having three days off, then working four day shifts in a row.

A rotation that goes from days (8:00 A.M. to 4:00 P.M.) to evenings (4:00 P.M. to midnight) to nights (midnight to 8:00 A.M.) is a clockwise rotation. A rotation that goes from days (8:00 A.M. to 4:00 P.M.) to nights (midnight to 8:00 A.M.) to evenings (4:00 P.M. to midnight) is a counterclockwise rotation. If there is no pattern or if workers are asked to come in on a random schedule (as is common for long-haul truck drivers), the schedule is referred to as irregular. A split shift is one in which the workday is split by a few hours of no work (more accurately, no pay), usually in the middle of the workday. The worker might be paid for four hours, not paid for four hours, then paid for another four hours. Thus, the worker is being paid for eight hours even though he or she might be away from home for twelve.

In general, fixed schedules are better than rotating schedules for establishing a regular sleep pattern and lifestyle. Rotating schedules are better if the rotations are clockwise. People should avoid work schedules that do not allow sufficient time to deal with family issues or social time. What is the best shift for workers who are also the primary family caregiver, for example? If the children are very young, working an evening or a night shift might make it easier for the caregiver to enlist relatives in helping to care for the children.


People should take care not to leave the boring tasks to the end of the day; they might find it difficult to finish. Workers with dangerous jobs or work that incurs risks for others (for example, heavy machinery operators, ships’ pilots, air traffic controllers) should make sure that there is a system in place that allows them to be relieved for a rest if they become too sleepy. They might even ask co-workers to warn them when they seem to be losing alertness, and should do the same for others. Spending as much time as possible in well-lighted areas will help keep workers alert, as will eating healthy and nutritious meals and snacks.

Taking naps at appropriate times during the workday can also be a life-saver for shift workers, especially those on irregular shifts. Workers should investigate whether the employer has a napping policy. A short, fifteen-to thirty-minute nap can dramatically improve alertness for several hours even for a very tired person. Increasingly airlines, for example, are beginning to allow copilots to nap on long-haul flights. The naps must not be too long, however; people who fall into a deep sleep might wake up groggier than they were before the nap. Instead of having doughnuts and coffee during a break, tired workers should consider finding a place to sack out.

Some people will use caffeine in its various forms to try to be alert. Two related products that increase alertness that have been approved by the U.S. Food and Drug Administration for use in “shift-work sleep disorder” are modafinil (Provigil) and armodafinil (Nuvigil).


If these strategies are insufficient to help workers cope with their schedule, they should try to change it, even when doing so offers a number of challenges. Some strategies might involve talking with the employer or their union to see what compromises and changes can be made. Workers can make their employer aware of the impact of shift-work schedules on the health and productivity of employees. They can find out whether the work schedules violate labor laws. They should explore the origins of the schedule: Did it come from the employer, the union, a consultant—was it the result of a labor negotiation? In many jobs, a work schedule might have been in place for decades, without anyone giving it much thought. Some companies might be prepared to change schedules based on new scientific information about worker productivity and sleep needs.

Workers might also ask other employees what they think about the schedule, and check to see whether similar industries have better schedules. Before talking to their employer, workers should arm themselves with the appropriate research and any other materials available that can strengthen their case. They should approach the employer not with the problem but with a proposal for a solution, such as a better shift schedule. They might suggest that the company consult with experts to advise them on how to improve schedules. If they present the information in a positive way that would enhance the productivity of the workplace, reduce absenteeism, and improve the health of the workers, they will increase the chances of getting positive action from the employer.

Workers should also educate themselves about what benefits they are entitled to and what protections they have under the law, through the union, or via the employer’s own written policies. Most communities operate under federal laws or local regulations that protect workers. Some industries, such as aviation, are closely regulated. Others have regulations that are sometimes loosely enforced—for example, the trucking industry and medical training facilities. One set of regulations may act counter to another set of regulations; in some communities doctors in training were at one time forced to spend more than a hundred hours a week on duty because hospitals argued that these doctors were “training,” not “working,” which justified their ignoring labor laws. In 2003, and later in 2011, the ACGME, as part of its regulation of medical training programs, started to enforce schedules that do not permit trainees to work more than eighty hours a week. Not all areas are improving, though. At present, a pilot may not be on active flight duty for more than eight to ten hours a shift, but a hospital staff surgeon may operate even if he or she has been awake for thirty-six hours.


For workers on the night shift, here are some tips for managing their sleep schedules and staying safe and healthy. First, they should consider forming a carpool. Besides saving on gas, having several people in the car helps the driver to remain alert. Some employers might be prepared to provide taxi transportation home for shift workers if it is not safe for them to drive. If it is sunny outdoors, wearing wraparound sunglasses will help workers who plan to sleep as soon as they get home since exposure to bright light in the mornings might reset their body clock and make it difficult for them to sleep. They should avoid eating heavy meals or drinking alcohol before sleeping. Having a big dinner at breakfast time will make it harder to sleep and might result in weight gain. Drinking alcohol might cause the person to wake up within a few hours. It is not advisable to take sleeping pills when adjusting to or managing a difficult work schedule. Medical science does not know how safe such medications might be over months or years of use.

Workers on night shifts should also make sure that the home environment is conducive to daytime sleep. This might involve installing heavy blinds that darken the bedroom, setting the phone to an answering machine or voice-mail, or simply turning off the phone’s ringer. In fact, they should turn off all gadgets.

They also need to communicate with family and friends about their sleep requirements so that all will respect their sleep schedule. They might even speak to their neighbors, explaining that they have a job that requires shift work and that they have to sleep during the day. They can politely request that neighbors not make noise that might disturb their sleep. Workers on rotating shifts might even give the neighbors a schedule of which days are affected. Thank-you notes and reminders will usually win their cooperation and understanding. Above all, daytime sleepers should do whatever they need to do to ensure that noisy distractions of any kind are minimized. If loud noise is unavoidable (for people living near an airport or on a bus route, for example), sleepers might find earplugs helpful. Sometimes the only quiet place for daytime sleeping is a remote spot in the basement!

Back to the Sleepy Bus Driver

The bus driver worked a split shift. Every morning, she awoke at 4:00 A.M. to make lunches and get the day organized for her husband and children. At 5:00 she left for the bus terminal and started work at 6:00. Her morning shift was four hours; she finished at 10:00. Between 10:00 and 3:00, she hung around the bus terminal because she did not want to spend two hours going back and forth to her home. Her afternoon schedule was set for rush hour, between 3:00 and 6:00. After she returned to the terminal, she made her way home, arriving at roughly 7:00. Besides being exhausted when she got home, she had little time to divide between her family and sleep. She normally went to sleep at around 10:00, so on average she slept only six hours a night. No wonder she was a wreck and could barely stay awake on the job. After we discussed various options, I contacted the patient’s union and employer to see whether anything could be done about her shift schedule since, in my opinion, the schedule was endangering both the driver and the public. I got nowhere. The employer told me that the shifts were controlled by the union. The union head told me that it was too bad that she could not handle the schedule, but better work schedules were reserved for drivers with more seniority, and she would have to work several more years before her schedule would change.

The patient and I discussed the pros and cons of her split shifts, and she decided that her health and her family were more important to her than the job. She decided to change careers. She took another job driving a grocery delivery truck. Her shift ran from 7:00 A.M. to 3:00 P.M. Her income decreased a bit, but she was much happier—and healthier.

Today’s twenty-four-hour world might improve productivity, but society could be paying too high a price. Night work, using computers and social media on devices at night, combining professional work with family care, even exploring the range of activities available to children have led to sleep deprivation. One of the most serious results of today’s work schedules has been the increase in sleep deprivation among night-and irregular-shift workers. As a sleep specialist, I have encountered an appalling lack of knowledge about the health consequences of shift work by people who were in a position to help their employees, and who should have been motivated to do so, if only to increase their company’s productivity and improve customer safety.