Jet Lag: Biological Clock Travels With Alarm

Just before the space shuttle Columbia streaked into orbit earlier this month, its seven astronauts underwent an unusual middle-of-the-night ritual.

In Houston and at Cape Canaveral, they were exposed to carefully timed periods of simulated daylight for several nights straight. The idea was to help the astronauts’ body clocks--which researchers believe are directly affected by cycles of light and dark--adjust more quickly to their scheduled 1:30 a.m. launch.

“Within a couple of days--and by the time of the launch--they were all sleeping well during the day and able to be awake and fully alert at night,” says Dr. Charles Czeisler, the Harvard University scientist who designed the program.

Here on Earth, the malady Czeisler helped the astronauts avoid is known as jet lag. It results when body and mind are pressed into doing things at a time in the 24-hour cycle when they are accustomed to doing something else.

Jet lag and its accompanying problems have received new attention because of President Bush’s intensive travel schedule in recent months. Some wonder whether all his globe-trotting has impaired the 66-year-old chief executive’s performance.

The issue is important because the combination of travel fatigue and absence from the White House could seriously affect the President’s ability to make major policy decisions, particularly at a time when war may be looming in the Mideast. Since the Iraqi invasion of Kuwait Aug. 2, Bush has been out of town 70 days.

Several of his longtime advisers have suggested recently that the President’s penchant for travel continually makes it difficult to keep him focused and may actually be distracting him from tackling important problems.

They also blame Bush’s heavy--and inevitably tiring--travel schedule for several of his recent gaffes, including the time he allowed photographers to catch him in an animated pose with Syria’s President Hafez Assad.

The same questions also have emerged over the impact of jet lag on his top aides, who often must endure the same rigorous travel agenda as their boss.

“What we’re talking about is a basic biological issue,” says Dr. Fred Turek, chairman of the neurobiology and physiology department at Northwestern University in Evanston, Ill.

“Your body has a basic clock inside, located in the brain, and it regulates most 24-hour rhythms. You are a different person at one time of the day than you are at another. If you have a clock on your wrist you can move it eight hours, whereas your body clock adjusts gradually, usually over a period of five to 10 days.”

Nevertheless, millions of Americans continue to believe--and behave--as if they can function well on less sleep or in situations where their normal circadian rhythms--those keyed to the body clock--are disrupted.

“We have a tradition of feeling that the successful person doesn’t need much sleep and that it’s macho to get by on only a few hours of sleep a night,” says Dr. Andrew Monjan, chief of the neurobiology of aging branch of the National Institute on Aging.

“Thomas Edison talked about needing only two or three hours of sleep a night,” adds Monjan, also executive secretary of the National Commission on Sleep Disorders. “And I’m always reading stories about White House aides who come in and work 18- to 20-hour days, and eat their meals at vending machines. They’re proud of it. It’s a mark of success.”

But experts insist that the problems associated with jet lag and sleep deprivation are inevitable and cannot be overcome simply by willpower.

“It’s not a question of being tough enough,” Turek says. “That would be like saying: ‘I don’t need to breathe anymore. I don’t need this oxygen.’ ”

The biological body clock is highly synchronized to the physical environment and its changes, primarily to light cycles, the experts say. Tamper with your biological body clock and you are asking for trouble, they warn.

“The body is finely tuned to the periodic light-dark cycle of the environment,” says Czeisler, who also directs the circadian and sleep disorders laboratory at Boston’s Brigham and Women’s Hospital. “That synchronization is disrupted by travel.”

Researchers are convinced that the effects of jet lag--which can be compounded by multiple changes in time zones--can have a profoundly damaging impact on short-term memory, attention span, judgment, cognitive skills and the ability to come up with innovative solutions and new concepts.

“Errors caused by inattention are very common,” Czeisler says. “It becomes very difficult to assimilate new information. Also, there is a significant disruption of divergent thinking, the way we come up with new perspectives on a situation--the process thought to be very important to creativity.”

Further, the mismatch between what time of day it is in the body and what time of day it is in the local environment also can disrupt other body functions, including respiration, body temperature, digestion and the workings of the heart and kidneys, they say.

“A kidney puts out urine at three times the rate during the daytime as it does at night,” Czeisler says. “That’s why we can sleep more soundly.”

Researchers draw a distinction between disruption of the body clock and sleep deprivation. Failure to get enough sleep obviously can occur without travel. But the opposite is not true: cross a few time zones and sleep deprivation is inevitable.

“Your sleep is more disturbed, not just by the travel itself but by the fact that you’re trying to sleep at the wrong biological time,” Czeisler says. The weary traveler also will find that he experiences involuntary “micro-sleep” episodes--periods where he briefly nods off--often at inopportune times, Czeisler says.

Research has shown that sleep deprivation seems to have a greater impact on cognitive skills than physical ones. A study conducted by the Army’s Medical Research and Development Command, for example, shows a 25% decrease “in the ability to think, plan and execute with every 24 hours awake,” according to Dr. Gregory Belenky, chief of its behavioral biology department.

Scientists believe that the body clock is located in the brain near the hypothalamus, in an area called the suprachiasmatic nucleus.

“When we destroy it (the body clock) in animals, the animal maintains a continual level of wakefulness and sleeps very little,” Monjan says.

Further, he says, “there have been some recent studies where they’ve taken cells from the suprachiasmatic nucleus of a young animal and transplanted them into animals where the cells had previously been removed--and the clock was reinstated.”

Monjan says that some studies have shown that it takes people older than 65 longer to recover their circadian rhythms than those who are younger. Although there is no research yet to explain why, scientists speculate that it may be related to a loss of cells from this region of the brain. Monjan says studies have shown that hamsters lose these cells with aging. The same may happen with humans, he says.

Scientists are working on ways to speed up the adjustment to jet lag, such as Czeisler’s work with artificial light. Earlier, the members of the Columbia shuttle crew had tried on their own to accommodate the upcoming change in schedule, but had been unsuccessful, he says.

“They were trying to sleep during the day and taking sleeping pills and trying to stay awake at night and were having great difficulty staying awake and being alert,” he says.

The NIH’s Monjan says that the use of bright light therapy to reset the circadian clock has not yet been studied in a large-scale clinical trial. “But the evidence thus far shows that it works in a number of cases,” he says.

Researchers stress that using such aids as special diets and sleeping pills are ineffective at best and dangerous at worst. Secretary of State James A. Baker III, whose travels have been as extensive as Bush’s, frequently takes the drug Halcion, a sleeping aid, to force sleep, according to sources who travel with him.

“Sleeping pills actually interfere with sleep because they don’t produce normal sleep,” Czeisler says. “And they don’t facilitate the resetting of the biological clock.”

Monjan says that with Halcion, “some people find no adverse effects. Others suffer transient amnesia. Some people find it disturbs their mood. The effectiveness really depends on how the individual responds to the pill.”

As if jet lag itself weren’t bad enough, some researchers have described another travel-related phenomenon, similar to jet lag, which they call “jet bounce.”

Dr. Benjamin Natelson and his colleague, Walter Tapp, both of the New Jersey Medical School and the East Orange Veterans Administration Medical Center, subjected monkeys to jet lag by turning on lights six hours earlier in the morning, thus simulating a trip from Newark, N.J., to Paris. Then they observed how well the monkeys performed tasks that they had learned previously.

“What happens is what you’d expect: for the first three days, their performance fell like a stone,” Natelson says. “They started making mistakes. They took longer. Just what happens to humans. Everyone knows that.”

After about a week, when the animals’ biological rhythms had become reset to the new time zone, their performance returned to normal--also not a surprise.

But then, to the researchers’ astonishment, after about 10 to 12 days in “Paris,” the animals began performing badly again. “All of a sudden, they started making mistakes--not as severe as the first ones but they made mistakes again,” he says.

Natelson and Tapp cannot explain this secondary “jet bounce.” Since they only measured two of the animals’ body rhythms in the experiment, they theorize that perhaps there are other body rhythms that are not reset, even after 10 days. Or they speculate that perhaps jet lag is not as closely tied to the disruption of body rhythms as most researchers believe.

Natelson says there is no scientific evidence that this occurs in humans.

“What causes it? We don’t know,” he says. “When people get better from jet lag, they assume it’s done. Finished. Maybe this means you can do a good job for a few days but fatigue will catch up.”

Ultimately, increased understanding of the workings of the body clock could have widespread applications, both in science and in practical application--especially in developing better ways to ease the effects of extreme international travel.

But researchers stress that it is still a new and evolving science.

“We’ve only had the first hint of where the clock was located,” Turek says, noting that researchers first discovered it in 1972. “This is relatively recent. We’ve known where the heart is for 500 years and still don’t know everything about how the heart works. We’ve only known where the clock is for less than 20 years.”