Overnight Workers

When night is day

by Susan Kruglinski

August, 2001

 It's 2:30 am, and the Jewel supermarket in northern Chicago is strangely dim, with many of the overhead lights turned off to save energy. There are not enough customers to warrant a waste of electricity on the overnight shift. In a t-shirt and jeans, 22 year-old Gregory Piske is lugging around crates of bottled water and arranging items on the supermarket shelves.

 "My good days outnumber the bad," he says of his ability to cope with doing a 10 pm to 6 am shift five days per week for the past year and a half. "I have fewer days where I move slower." During the first year, he explains, his problems functioning on the job were so bad that co-workers would express concern. "And I would sleep at least 12 hours a day," he recalls. Lately his body and mind have been adjusting to his schedule. He is generally alert at work, and he now sleeps soundly for six hours, from 9 am to 3 pm "Luckily, I'm notorious for my ability to sleep through just about anything," he says.

 More than 15 million people in this country, or almost 17 percent of the work force are, like Piske, shift-workers; that is, workers who do not work the typical nine-to-five hours. Forty-two percent of these workers are in the service industry. There is a trend in America towards a more service-based economy, and when it comes to service, more and more of us demand it 24 hours a day. At any hour, we expect someone to be on the other end of our phones, ringing up our merchandise, preparing our food, and keeping us healthy and safe.

 For overnight workers, part of the job is to fight the body's natural cycle and stay awake until morning. As every faculty of their body switches gears to prepare for sleep, these workers struggle against their own biology. And as the world around them crawls into bed at night and starts fresh as the sun rises, they must also run counter to the flow of society and family.

 Very likely, we do not think about the physical health and family life of the nurses, cab drivers and hotline workers whose availability we take for granted. We also do not consider the diminished productivity and even the dangerous circumstances that can be the result of a sleep deprived worker.

 As this working population explodes in numbers into the 21st century, sleep researchers are wondering how these mostly blue collar workers are faring, and how they can be helped to perform efficiently and remain sane, safe and healthy.

 For some overnight shift workers, this is not as hard as it sounds. "I'm like a vampire," says Denise Walker, a 48 year-old security guard and UPS employee from the South Side of Chicago. "When daylight comes, I want to sleep. I get a burst of energy when night comes." Walker, who has raised three children with her husband and the help of her mother-in-law, has held two jobs since 1989, one of which has always been an overnight shift. "I would go to bed at three, four or five in the morning anyway," she says. "I love my nights."

 "It's very self-selecting," says Kathryn Reid, a research assistant and professor at the Center for Circadian Biology at Northwestern University, who got her Ph.D. studying overnight workers at the University of Adelaide in Australia. "If you cope, you stay. And if you don't, you leave. Fifty percent of people who start shift work leave within the first two to three years if they can't cope."

 Some blame Henry Ford for the launch of the 24-hour society, with his invention of the continuous conveyor belt which allowed for non-stop production. But overnight employment has been diversifying beyond repetitive physical labor, nursing and security. "Now with tele-business and computer hotlines and that sort of thing, people are working around the clock in a lot of different professions," says Reid.

 Between 1985 and 1997, the number of shift workers rose by 30 percent, while the overall work force rose by only 23 percent, according to the National Center for Sleep Disorder Research. While women make up most of the service industry, men are more likely to work the night shift, and African Americans do more overnight work than whites and Hispanics combined. The typical overnight worker is either never-married or divorced. For those workers who are married, the risk of divorce is greater than for people who keep regular hours.

 Sleepy workers cost the nation about $18 billion a year in lost productivity, the National Sleep Foundation estimates, and according to a poll they conducted, about 29 percent of shift workers say they are so tired at work that they cannot perform their duties at least several days per week. Studies have found that shift workers tend to interact less, communicate less, and double-check less as they work. Chernobyl, Three Mile Island, and even the Challenger disaster have all been blamed on errors performed on an overnight shift. In 1999, the National Highway and Traffic Safety Administration helped launch a much-publicized campaign, distributing educational materials to shift workers and awarding testing grants, in response to its estimates that more than 1,500 traffic deaths and 40,000 injuries occur each year at least in part because of fatigue. This can occur on the drive home from work, or during an overnight drive that is part of the job, as with truck, taxi, and bus drivers.

 "If you're doing a task that is boring or monotonous, it's going to be much more affected by sleep loss," Reid says. "If you are driving along an empty road or if you're monitoring a screen, it's going to be harder to maintain your performance. The big problem with night shifts is that people generally don't have a whole lot to do."

 In addition, overnight workers average only 4.6 hours of sleep per day -- up to three hours less than the average day worker. Over time, the accumulated lost hours become a "sleep debt," which compounds itself for each night -- or day -- the lost sleep is not replenished. The results are disorders that affect almost every function of the body. As scientists continue to examine sleep debt and overnight shift work, the list of physical problems continues to grow. Obesity, high blood pressure, gastrointestinal disorders, impaired immune response, and even an increased risk of cardiovascular disease, reproductive dysfunction and clinical depression have been named as long-term consequences of working overnights.

 "We're designed to sleep at night and be active during the day," Reid says, "So if you're doing the opposite, a lot of your functions are impaired." Gastrointestinal problems are the most common physical symptoms, she says, because workers are "not eating at the right time of day for their body clock, and the digestive juices that would be there during the day are not there at night."

 But some of the common symptoms of sleep deprivation are more grave than a simple upset stomach. "With just one week of sleep reduced to just four hours a night, you can enter an almost pre-diabetic state," says Reid. "Your glucose tolerance and your insulin metabolism are impaired to a similar degree as people with diabetes."

It is 4 am in the Medical Center district of Chicago. In a desolate neighborhood across the highway from a cluster of hospitals, in a Rush-Presbyterian-St. Luke's Medical Center office building, all the lights are out and all the rooms deserted. Well, almost all. There are lights on in the hallways and lobby where the security guard is fast asleep on his stool. There are also lights on in a few rooms on the fourth floor, in the Biological Rhythms Research Laboratory.

 Here, at the end of a four-hour game of Monopoly and a meal of microwaved spaghetti and 7 Up, three research subjects, who for the past week have been forcing themselves to stay awake all night, must get on a computer and test their ability to function. The computer asks "How do you feel right now?" and the men must choose from "fresh as a daisy," "full of pep," "tense," "gloomy" or "physically exhausted." They must memorize words such as "quarter," "justice," "band," and "milk" and recall them minutes later. They match symbols, estimate lengths of time, and hit a button whenever numbers suddenly appear on the screen.

"Basically we play games and eat all night," says James Beragé, a 31 year-old who just came to town after losing his dot-com job in Silicon Valley. "We get progressively more bloated with salty food and at the same time we get light-headed, anxious and jittery."

"I'm surprised how easy it is," says 21 year-old Mike Sullivan, a communications student from DePaul University with light brown dred locks.

Twenty-two year-old, pony-tailed Josh Salzman, a UIC labor history graduate student, chimes in, "Its no trouble at all." 

"I already have a pinched nerve from the stress," says Beragé, wincing and rubbing his neck.

Generally, the older the overnight worker is, the harder it is to keep physically together and do the work properly. The older person will also feel less refreshed after daytime sleep. "Young, single people are the ideal shift workers," says Helen Burgess, a Postdoctorate Fellow at the Biological Rhythms Research Laboratory. There are also pedigrees, where family members are "phase advanced" or "phase delayed" -- the scientific jargon for early risers and night owls. These folks have a sleep cycle that is several hours earlier or later than the norm, and tend to remain that way for the rest of their lives. Burgess says innate "morningness" or "eveningness" appears to be genetic.

The research study Rush-Presbyterian-St. Luke's is conducting examines ways to minimize the unhealthy impact of overnight shift work on people who are not naturally "phase delayed" -- which is most of us. In the past, studies have proven that to ideally minimize circadian maladjustment, workers should be exposed to hours of bright lights during the night and wear dark goggles during the commute home. Because it is usually not practical for an overnight waitress to sit on the subway with goggles on her face, the laboratory is looking at more subtle ways of adjusting the shift of the circadian rhythm.

The twenty-seven research subjects -- three at a time -- are forced to stay awake until 8:30 am for a total of seven nights, some with moderately bright lights shined on them, some without. They are given 1.8 milligrams of melatonin or a placebo, and all are given sunglasses of varying degrees of darkness to wear on their way home. The research team covers the subjects' bedroom windows with dark plastic and installs air conditioning to produce the preferred sleeping conditions. These paid volunteers are required to lie in bed from 8:30 am until 3:30 pm, with the hope that they will sleep. Beragé reports, "I just lay there in the dark for seven hours."

The expectation is that the researchers will find practical solutions for overnight workers, whether it is driving home with sunglasses or getting employers to install proper lighting to keep productivity going.

To make sure the subjects are doing what they are supposed to be doing when they are not at the lab, the subjects wear Activity Monitors, which are wrist bands with little black boxes, like a watch, and Light Sensors, which are similar black boxes worn around the neck. An entire day of movement and light exposure is recorded and then downloaded into a computer, and finally printed out in the form of wavy lines. According to Sullivan, when he, Beragé, and Salzman take the train home together, with their matching black boxes and dark sunglasses, they are looked upon with great suspicion by fellow commuters.

 Besides the constant computer tests, the subjects are tested for awakeness through their saliva. Melatonin levels can be detected through blood or saliva samples, and the subjects are asked every 30 to 60 minutes to chew a cotton ball (Sullivan: "They could have at least flavored it!"), which is then spun in a centrifuge so quickly, two milligrams of spit are extracted These men should be thankful, as many sleep studies take constant rectal temperatures, one of the most accurate means of obtaining a measure of the all-important, crucially influential circadian rhythm.

* * * * * *

"Heart rate, blood pressure, intestinal juices, performance, sleep...pretty much anything you can measure has a 24-hour rhythm," Kathy Reid says, trying to explain circadian rhythm.

The word "circadian" is literally Latin for "about a day." The rhythms are controlled by an area of the brain called the suprachiasmatic nucleus. The light and dark cycle of day and night is the major influence on this rhythm, since our exposure to it directly affects the hormone melatonin, which in turn affects our body temperature.

"Melatonin is controlled by light coming in through the eyes," Reid says. "If you give extra melatonin to people during the day when the levels are low, it will reduce their body temperature and will increase the ability to fall asleep." The overwhelming need to sleep is brought on partly by the natural lowering of the body's temperature. The lowest point of temperature is one of the best marker's of the circadian phase, with the nadir at about four or five in the morning in a normal healthy person.

No one is absolutely certain why we need to sleep. Some compare it to hibernation in wild animals, when the body cools down, metabolism slows, and energy stores are replenished. Many feel that slow-wave sleep -- the deep kind, when you do not dream -- allows the body to restore its physical reserves. During REM sleep, when we do dream, it is proposed that the brain is sorting through the day's cerebral input, filing away memories and discarding psychological detritus. There is also evidence that our immune system recuperates while we sleep.

Researchers believe that in overnight workers, not only is the amount of sleep lessened, but the quality of the sleep is diminished, with less deep wave sleep.

So besides the physical dysfunctions, there is an accumulation of psychological deterioration -- a subject that has not been researched very thoroughly. Symptoms experienced by overnight workers include "sleep inertia," when a person awakens from a nap or minisleep feeling confused, irritable, and low functioning, and "transient memory loss," which is a difficulty in maintaining a train of thought. "Peripheral hallucinations," also common, are detections of movement out of the corner of the eye that are not there. "Automatic behavior syndrome" is when a person can continue to perform a routine duty, such as driving a truck or working an assembly line, but will at the same time become completely incapable of active cognition for several minutes. They are physically working, but are mentally checked out. And "night shift paralysis" is a rare, frightening problem. An overnight worker will suddenly find himself unable to move, speak or react to stimuli. He will become helplessly paralyzed with lack of sleep.

 * * * * * *

"My social life hasn't been all that much lately," says Gregory Piske. "There are so many people I want to call, but when I'm sleeping, they're up. And when they're sleeping, I'm up."

Piske, who feels the loss of social life is the worst drawback to working overnights, is alluding to a problem that can be no less devastating than the biological difficulties of overnight work. Shift workers in marriages with children often work at different times than their spouses to make sure the kids have constant care. The risk of divorce for these couples can be three to five times greater than for couples who keep regular hours, according to an extensive study conducted at the University of Maryland. And single parents are usually juggling child care, work and irregular hours with little or no assistance. Singles without children have the more basic problem of simply not having a social life.

Of course, for those with naturally antisocial tendencies, the solitude of shift work can be seen as a benefit. "I'd rather be by myself," says security guard Denise Walker. "On the night shift, there are less people hassling you about little things. I don't like traffic, and I don't like crowds."

Indeed, for some, overnight work seems to be a perfect fit. Many enjoy the lack of supervision, the relaxed pace, the flexibility to run errands and care for family during the day, and, frequently, the slightly larger paychecks.

"I do recommend it," says Piske. "I've actually invited a few friends to come work here." After pausing a beat, he adds, "But maybe that's the social thing again. It's me not being able to see them."

Then, glancing over his shoulder, Piske says in a low voice, "I would like to switch to days if the opening ever comes up."