Jet Lag Essay

Making A level psychology easier

The consequences of disrupting biological rhythms - shift work and jet lag
What are the effects on people of jet leg and shift work?

How can the effects of jet lag be reduced?

How can shift work be made easier to cope with?

Jet Lag
Jet lag occurs when we travel rapidly across time zones.
  • Flying from London to New York takes around 6 hours.
  • If you leave London at noon, you will arrive 6 hours later and your body will feel as though it is 6PM, however it will only be 1PM. Your body will be ready for sleep when it is 7PM locally.
  • This conflict between local time and your biological time leads to tiredness and confusion.

Disruption of the circadian rhythm by jet leg can affect the performance and alertness of business people attending meetings in other countries, air crew, sports players, and so on. Recht, Lew and Schwartz (1995) found that baseball players in the USA won 44% of games when they travelled from the east coast to the west coast, but only won 37% of games when they travelled from the west coast to the east coast. This shows that travelling from east to west is less harmful to the circadian rhythm than travelling from west to east.

Travelling from east to west leads to phase delay of the body clock, which seems easier for the body to cope with than phase advance. Phase delay simply means extending the duration of a rhythm’s cycle (e.g. from 24 hours to 29 hours before returning to 24 hours again), whereas phase advance means shortening the rhythm’s cycle.

Coren (1996) offers advice for minimizing the effect of jet lag:
  • Catch up on sleep before flying to avoid starting with sleep deprivation.
  • During the flight, adopt the daily routine of the destination’s time – e.g. if you are going to arrive at night time then try to sleep on the plane.
  • Adopt the destination’s time (and zeitgebers) as soon as you arrive.
  • Avoid consuming stimulants and depressants such as alcohol and caffeine.
  • If it is morning then expose yourself to as much sunlight as possible in order to reset your biological clock.

Consuming melatonin may help resynchronise the sleep-wake cycle more quickly. Beaumont et al (2004) found that taking melatonin at bed time for 3 days before travel and 5 days after significantly reduced the symptoms of jet lag.


Shift Work
Shift workers are expected to be alert, productive and safe at all times of day and night, however working at night and sleeping during the day is clearly contrary to the normal sleep-wake cycle. The Exon Valdez disaster, Chernobyl nuclear disaster, sinking of the Titanic, and the Piper Alpha disaster are all examples of catastrophes involving shift workers and, although it is not an established fact in these cases, there could well have been an impairment in the performance of workers during the events that caused the disasters.

Artificial lighting makes it possible for humans to be active at nighttime and allows us to work over a full 24-hour period. Factory workers operate heavy machinery, lorry drivers travel long distances, doctors have responsibility for patients’ lives, and air traffic controllers make fast decisions at times when their body clocks (circadian sleep-wake cycles) are completely out of synchronization with the environment. It is therefore vital to understand the effect of working at night and sleeping during the day on safety, productivity and health.

Czeisler et al (1982) found that shift workers at a Utah chemical plant reported high levels of stress, difficulty sleeping, and health problems that affected productivity. The workers were on a backward shift rotation (nights then afternoons then mornings) which was causing their sleep-wake cycles to phase advance (effectively shortening the 24 hour cycle). Czeisler introduced a forward shift rotation (nights then mornings then afternoons) to phase delay the sleep-wake cycle, and placed workers on each shift stage for 21 days to allow the body clock time to fully adjust. After 9 months the workers reported less stress, found sleeping easier, and had increased productivity.

Gordon at al (1986) changed Philadelphia police officers from a backward shift rotation (phase advanced) to a forward shift rotation (phase delayed), with the result that the police officers were more alert and had 40% fewer accidents.

An effective alternative to rotating shift patterns is permanent non-rotating shift work (i.e. always working nights or evenings). Phillips et al (1991) found that when this was introduced for Kentucky police officers, the rate of sleeping at work was lower and they also had fewer accidents. Permanent shifts, however, can lead to other problems as they cause difficulty with social and family life.

Artificial light can have a significant effect on the sleep-wake circadian rhythm. Boivin et al (1996) investigated the power of artificial lighting at resetting biological clock. 31 male subjects were divided into four groups and put on an inverted sleep-wake cycle for three days (to mimic night workers). Each ‘day’ when they awoke they were exposed to five hours of very dim light followed by:
1. Very bright light 10,000 lux
2. Bright light 1260 lux
3. Ordinary room light 180 lux
4. Dim light
After three days the sleep-wake cycles for members of group 1 had advanced five hours earlier, group two by three hours, group 3 one hour and 4 had drifted one hour later. This study shows that even room light can have an effect on circadian rhythms, and has important implications for the type of environment that employers should provide for employees to work in - if a shift worker is to adapt to an inverted sleep-wake cycle quickly, then they should be exposed to very bright light when working at night.

The most effective ways to cope with rotating shift work are:
  • Work a forward rotating shift pattern. This allows the sleep-wake cycle to phase delay, which is easier to cope with than phase advance.
  • Remain on each shift stage for at least one week to allow the body clock to synchronise.
  • Work under bright lights at night and sleep in a dark room during the day. This creates exogenous zeitgebers that reset the body clock.
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Answering exam questions (PSYA3 AQA A specification)

Nathaniel Kleitman, known as the “father of modern sleep research,” was born in 1895 in Bessarabia—now Moldova—and spent much of his youth on the run. First, pogroms drove him to Palestine; then the First World War chased him to the United States. At the age of twenty, he landed in New York penniless; by twenty-eight, he’d worked his way through City College and earned a Ph.D. from the University of Chicago. Soon after, he joined the faculty there. An early sponsor of Kleitman’s sleep research was the Wander Company, which manufactured Ovaltine and hoped to promote it as a remedy for insomnia.

Until Kleitman came along, sleep was, as one commentator has put it, “a huge blind spot in the science of physiology.” No one bothered to study it because it was defined by what it wasn’t—sleep was a state of not being awake and, at the same time, of not being comatose or dead. (It’s unclear what exactly attracted Kleitman to this academically marginal topic, but it has been suggested that it fitted with his own marginalized background.)

In one of Kleitman’s first experiments, he kept half a dozen young men awake for days at a stretch, then ran them through a battery of physical and psychological tests. Frequently, he used himself as a subject. As a participant in the sleep-deprivation experiment, Kleitman stayed awake longer than anyone else—a hundred and fifteen hours straight. At one point, exhausted and apparently hallucinating, he declared, apropos of nothing in particular, “It is because they are against the system.” (Asked what he meant, he said he’d been under the impression that he was “having a heated argument with the observer on the subject of labor unions.”) In another self-administered experiment, Kleitman spent six weeks underground, in Mammoth Cave, Kentucky, trying to live according to a twenty-eight-hour day. (He found that he could not.)

In the early nineteen-fifties, Kleitman’s research was sponsored in part by Swift, the meatpacking company, which was interested in finding out whether feeding babies a high-protein diet would make them sleep more soundly. It was at this point that he—or, really, one of his graduate students—stumbled onto a great discovery. Casting around for a dissertation topic, the student, Eugene Aserinsky, decided to hook sleepers up to an early version of an electroencephalogram machine, which scribbled across half a mile of paper each night. In the process, Aserinsky noticed that several times each night the sleepers went through periods when their eyes darted wildly back and forth. Kleitman insisted that the experiment be repeated yet again, this time on his daughter, Esther. In 1953, he and Aserinsky introduced the world to “rapid eye movement,” or REM sleep. Another of Kleitman’s graduate students, William C. Dement, now a professor of psychiatry at the Stanford medical school, has described this as the year that “the study of sleep became a true scientific field.”

The discovery of REM sleep led to the elaboration of a whole taxonomy of sleep. In Stage 1, the brain emits what are known as theta waves, which are slower and more regular than the waves emitted by a brain that’s awake; in Stage 3, it emits delta waves, which are even slower and have a much higher amplitude. (A person can be woken from Stage 1 sleep by a slight noise; by Stage 3, he might sleep through a loud crash.) Primates, marine mammals, birds, even fish have their own sleep patterns. Mouse lemurs, from Madagascar, snooze for more than fifteen hours a day, but only an hour of this is REM sleep. Bottlenose dolphins sleep with half their brains; this prevents them from drowning. Thrushes catch up on sleep by taking “catnaps” of less than thirty seconds apiece.

New technologies have made the study of sleep cheaper, easier, and less intrusive. In 2003, one expert in the field announced the “dawn of the golden age of sleep research.” Since then, hundreds, perhaps thousands, of academic papers have been written on topics ranging from “sleep problems among Chinese school-aged children” to the “sleep behavior of the wild black rhinoceros.” Currently, in the United States alone, more than two thousand sleep clinics are in operation. All of which raises the question: If this is sleep research’s golden age, then why are we all so tired?

Of the many ways that things can go wrong in bed, sleep troubles are probably the most prevalent. According to a 2011 poll, more than half of Americans between the ages of thirteen and sixty-four experience a sleep problem almost every night, and nearly two-thirds complain that they are not getting enough rest during the week. The National Academy of Sciences estimates that fifty to seventy million Americans suffer from a “chronic disorder of sleep and wakefulness.” The results are dangerous as well as annoying. A recent study by the Centers for Disease Control and Prevention revealed that almost five per cent of adults acknowledge nodding off at the wheel at least once during the previous month. The U.S. Department of Transportation has determined that what might be called D.W.D.—driving while drowsy—causes forty thousand injuries a year in the United States and more than fifteen hundred deaths.

Our collective weariness is the subject of several new books, some by professionals who study sleep, others by amateurs who are short of it. David K. Randall’s “Dreamland: Adventures in the Strange Science of Sleep” belongs to the latter category. It’s a good book to pick up during a bout of insomnia.

Randall begins with an account of his own sleep problems, which include laughing, humming, grunting, bouncing, kicking, and, on at least one occasion, sleep-walking into a wall. He considers a range of possible explanations for the national exhaustion—too much light, too much warmth, too much avoirdupois—and finds them all compelling. The electric light bulb has made darkness optional, eliminating the enforced idleness that used to begin at sunset. Modern mattresses and bedclothes trap the heat that the body gives off as its core temperature drops each night. Obesity increases the chances of developing sleep apnea, a condition that combines choking and waking in an exhausting, sometimes life-threatening cycle. For all these reasons and more, Randall anticipates a bright future for the emerging field of “fatigue management.” One sleep expert he interviews predicts that “fatigue management officers” will soon be as common at major corporations as accountants. Like time, sleep, it turns out, is money.

Perhaps the most provocative claim that Randall has to make about sleep is that we’d all be better off doing it alone. Research studies consistently find, he writes, that adults “sleep better when given their own bed.” One such study monitored couples over a span of several nights. Half of these nights they spent in one bed and the other half in separate rooms. When the subjects woke, they tended to say that they’d slept better when they’d been together. In fact, on average they’d spent thirty minutes more a night in the deeper stages of sleep when they were apart. Randall cites the work of Neil Stanley, a sleep researcher at the University of Surrey, in England, who likes to say that there’s only one good reason to share a mattress.

“The Slumbering Masses,” by Matthew J. Wolf-Meyer, takes a more polemical view of what might be called the “sleep question.” Wolf-Meyer, an assistant professor of anthropology at the University of California at Santa Cruz, spent four years interviewing just about everyone involved in sleep research: physicians, technicians, patients, members of patients’ families. He concludes that what Americans have come to think of as sleep problems are mostly just problems in the way Americans have come to think about sleep. “Normal sleep is always pathological sleep, or at least potentially so,” he writes.

Wolf-Meyer refers to the practice of going to bed at around eleven o’clock at night and staying there until about seven in the morning as sleeping “in a consolidated fashion.” Nowadays, adults are expected to sleep in this manner; anything else—sleeping during the day, sleeping in bursts, waking up in the middle of the night—is taken to be unsound, even deviant. This didn’t use to be the case. Until a century and a half or so ago, Wolf-Meyer observes, “Americans, like other people around the world, used to sleep in an unconsolidated fashion, that is, in two or more periods throughout the day.” They went to bed not long after the sun went down. Four or five hours later, they woke from their “first sleep” and rattled around—praying, chatting, smoking, or making love. (Benjamin Franklin reportedly liked to spend this time reading naked in a chair.) Eventually, they went back to bed for their “second sleep.”

Wolf-Meyer blames capitalism in general and American capitalism in particular for transforming once perfectly ordinary behavior into conduct worthy of medication. “The consolidated model of sleep is predicated upon the solidification of other institutional times in American society, foremost among them work time,” he writes. It is “largely the by-product of the industrial workday, which began as a dawn-to-dusk twelve-to-sixteen hour stretch and shrank to an eight-hour period only at the turn of the twentieth century.” So many people have trouble getting enough sleep between eleven at night and seven in the morning because sleeping from eleven to seven isn’t what people were designed to do.

Till Roenneberg, the author of “Internal Time: Chronotypes, Social Jet Lag, and Why You’re So Tired” and a professor of medical psychology at the Ludwig Maximilian University of Munich, also blames the modern workday for our general drowsiness. But Roenneberg sees this not so much as a by-product of industrial capitalism as a quirk of human physiology.

Each of us has an internal clock, or, to use Roenneberg’s term, a “chronotype.” Either we’re inclined to go to bed early and wake up at dawn, in which case we’re “larks,” or we like to stay up late and get up later, which makes us “owls.” (One’s chronotype seems to be largely inherited, although Roenneberg notes, not altogether helpfully, that the “genetics are complex.”) During the week, everyone is expected to get to the office more or less at the same time—let’s say 9 A.M. This suits larks just fine. Owls know they ought to go to bed at a reasonable time, but they can’t—they’re owls. So they end up having to get up one, two, or, in extreme cases, three hours earlier than their internal clock would dictate. This is what Roenneberg refers to as “social jet lag”—each workday, owls fall asleep in one time zone and, in effect, wake up in another. By the time the week is over, they’re exhausted. They “fly back” to their internal time zone on weekends and sleep in on Saturday and Sunday. Then, on Monday, they start the process all over again.

For larks, the problem is reversed. Social life is arranged so that it’s hard to have one unless you stay out late on Friday and Saturday nights. But, even when larks have partied till 3 A.M., they can’t sleep in the following day—they’re larks. So they stagger through until Monday, when they can finally get some rest.

According to Roenneberg, age also has a big influence on chronotype. Toddlers tend to be larks, which is why they drive their parents crazy by getting up at sunrise. Teen-agers are owls, which is why high schools are filled with students who look (and act) like zombies. Roenneberg advocates scheduling high-school classes to begin later in the day, and he cites studies showing that schools that delay the start of first period see performance, motivation, and attendance all increase. (A school district in Minnesota that switched to a later schedule found that the average S.A.T. scores for the top ten per cent of the class rose by more than two hundred points, a result that the head of the College Board called “truly flabbergasting.”) But, Roenneberg notes, teachers and school administrators generally resist the change, preferring to believe that the problem is insoluble.

The Sleep Disorders Center, in Albany, New York, is housed in a nondescript office building in a nondescript office park not far from Route 90. It’s about an hour’s drive from my house, and not long ago I decided to check myself in. I have trouble sleeping from 11 P.M. to 7 A.M., and I thought that, in the spirit of self-experimentation, it might be interesting to find out what was going on. I was told to report to the center one evening at eight. When I arrived, a receptionist showed me into a room not unlike what you’d find at a Holiday Inn. She handed me a consent form and advised me to go to the bathroom to change into my pajamas. In the bedroom, a camera on the ceiling was going to film everything I did.

The center was having a busy night, and for a while I was left on my own. I entertained myself by reading some pamphlets I’d picked up on my way in—“Drowsy Driving,” “Sleep & Depression,” “Narcolepsy and You.” At around 10 P.M., a technician came to fetch me. She measured my head from various directions—front to back, side to side—and began attaching electrodes: three on the back of my scalp, two on each temple, three more on my chin, two on each leg, and two on my chest. Each electrode trailed a color-coded wire, which got plugged into what looked like a backgammon board. Some rubber tubes were stuck into my nose and mouth, belts were wrapped around my chest and waist, and an oxygen monitor that emitted an eerie red glow was taped to my index finger. I and the wires and the backgammon board got into bed. The technician plugged the board into a data logger and attached two more wires to each of the belts. Then she wished me good night.

One of the great riddles of sleep is why we do it. Clearly, any animal that could get preyed upon is better off being alert, and even predators, when they’re snoozing, are losing time that otherwise could be used searching for victims. Yet sleep has a very long evolutionary history. It’s hard to measure a fruit fly’s brain waves, but even insects, which have been around for some four hundred million years, appear to need shut-eye. (Drosophila melanogaster, when they’re tired, creep away from their food, crouch down on their abdomens, and remain immobile for up to two and a half hours at a time.) In the nineteen-eighties, Allan Rechtschaffen and Bernard Bergmann, both, like Kleitman, sleep researchers at the University of Chicago, performed what is now considered to be one of the classic experiments in the field. It showed that rats, when totally deprived of sleep, would, after two or three weeks, drop dead. But Rechtschaffen and Bergmann could never figure out the precise cause of the rats’ deaths, and so, they wrote in a follow-up paper in 2002, even “that dramatic symptom did not tell us much about why sleep was necessary.” Rechtschaffen has observed that “if sleep doesn’t serve an absolutely vital function, it is the greatest mistake evolution ever made.”

What followed lights-out at the Sleep Disorders Center was, predictably enough, not sleep. (Imagine for a moment going to bed in a fuse box.) Every time I moved, I got tangled in a wire. My legs itched where the electrodes were attached. At one point, I scratched one of them off; the technician, who was monitoring my many data streams, immediately showed up to plug it back in. I decided that, since I was doing this more out of curiosity than clinical need, I could take the tube out of my nose. The technician disagreed. She showed up again and told me to put it back in. I imagined someone watching the videotape of me tossing and turning in the darkened room. I wondered how you could even make a videotape of someone in a darkened room: what would there be to see besides dark? I fell into the familiar rut of worrying about not being able to sleep, which made sleep seem only that much more elusive.

Finally, after what felt like several hours, I conked out. The next thing I knew, the technician was back, telling me it was time to get up. It was 6 A.M. I was desperate for coffee, but apparently sleep centers don’t believe in providing insomniacs with caffeine. I knew there was a Starbucks out by the Albany airport, about a ten-minute drive away. As I groggily made my way toward it, I thought of the “Drowsy Driving” pamphlet tucked in my bag. “There is no substitute for sleep,” it warned.

A few weeks later, I returned to the center to get my results. Dr. David Palat, a pulmonologist who works on sleep disorders, told me that a technician had scanned the data I had generated that night—nowadays, of course, sleep data are recorded by computer, rather than on a ream of paper—and had analyzed the information so that it could be presented in a series of tables. He handed me a six-page printout. The tables indicated that the night had not gone as badly as I had thought. It had gone a lot worse.

The first table showed that I’d spent six hours and forty-two minutes in bed, of which I had slept for four hours and two minutes. But I hadn’t lain awake for nearly three hours and then dropped off, as I’d imagined. A graph, known as a hypnogram, traced how I’d cycled from wakefulness through each of the sleep stages—1, 2, 3, and REM. A good sleeper’s hypnogram looks like sets of facing staircases. It traces a steady descent from wakefulness to REM sleep, then an ascent to a lighter sleep stage, then another steady descent, a pattern that gets repeated three or four times in a night.

My hypnogram looked like the Manhattan skyline. It turned out that I’d fallen asleep within about ten minutes of getting into bed. But, after only a minute or so, I’d woken up for about fifteen minutes. I fell asleep again and woke up, fell asleep again and woke up, fell asleep a fourth time and then remained awake for nearly an hour. Even when I’d felt that I’d finally conked out, I had kept waking up, for a mind-boggling total of a hundred and forty-one times. Most of these awakenings—a hundred and eleven—were brief, under fifteen seconds. The tables also showed that I’d stopped breathing eight times, which, Palat assured me, was not unusual, and had experienced seventeen “periodic limb movements,” also not uncommon. In his comments, Palat had written that my “sleep architecture” suggested “difficulty with sleep maintenance.” He advised me not to go to bed until I was sure I was tired; not to stay in bed when I couldn’t sleep but to go read in another room; and to eliminate alcohol.

In the weeks since, I have tried to follow Palat’s recommendations to the extent possible—I figure two out of three isn’t bad—and it would be nice to be able to report that I’m sleeping better. In fact, now that I’ve gazed on my hypnogram, nights are, if anything, harder. Sleep is vital, and sleep is a mystery. As Randall writes toward the end of “Dreamland,” the more you know about it, “the more its strangeness unnerves you.” ♦

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