How To Cope With Jet Lag

When travelers pass from one time zone to another, they suffer from disrupted circadian rhythms, an uncomfortable feeling known as jet lag. For instance, if you travel from California to New York, you "lose" 3 hours according to your body's clock. You will feel tired when the alarm rings at 8 a.m. the next morning because, according to your body's clock, it is still 5 a.m. It usually takes several days for your body's cycles to adjust to the new time.

Disruption of circadian rhythms is involved in changes in sleep patterns and can exacerbate the course of serious mood disorders, such as bipolar disorder and depression. Other types of illnesses also are affected by circadian rhythms; for example, heart attacks occur more frequently in the morning while asthma attacks occur more often at night.

To reduce the effects of jet lag, some doctors try to manipulate the biological clock with a technique called light therapy. They expose people to special lights, many times brighter than ordinary household light, for several hours near the time the subjects want to wake up. This helps them reset their biological clocks and adjust to a new time zone.

Symptoms much like jet lag are common in people who work nights or who perform shift work. Because these people's work schedules are at odds with powerful sleep-regulating cues like sunlight, they often become uncontrollably drowsy during work, and they may suffer insomnia or other problems when they try to sleep. Shift workers have an increased risk of heart problems, digestive disturbances, and emotional and mental problems, all of which may be related to their sleeping problems. The number and severity of workplace accidents also tend to increase during the night shift. Major industrial accidents attributed partly to errors made by fatigued night-shift workers include the Exxon Valdez oil spill and the Three Mile Island and Chernobyl nuclear power plant accidents. One study also found that medical interns working on the night shift are twice as likely as others to misinterpret hospital test records, which could endanger their patients. It may be possible to reduce shift-related fatigue by using bright lig hts in the workplace, minimizing shift changes, and taking scheduled naps.

Many people with total blindness experience life-long sleeping problems because their retinas are unable to detect light. These people have a kind of permanent jet lag and periodic insomnia because their circadian rhythms follow their innate cycle rather than a 24-hour one. Daily supplements of melatonin may improve night-time sleep for such patients. However, since the high doses of melatonin found in most supplements can build up in the body, long-term use of this substance may create new problems. Because the potential side effects of melatonin supplements are still largely unknown, most experts discourage melatonin use by the general public.

Melatonin, a hormone of the pineal gland also produced by extra-pineal tissues, acts as a biological response modifier; it is postulated to act as a mediator of photic-induced anti-gonadotropic activity in photoperiodic mammals (Budavari, 1989; Calbiochem, 1995). Secretion is reported to increase during the night; and in humans it is implicated in the regulation of sleep, mood, puberty, and ovarian cycles. The synthetic counterpart, which is available as a prescription and over-the-counter (OTC) drug/nutritional supplement as well as a fine organic chemical, has been promoted as an anticancer, radioprotective, contraceptive, antiobesity, antiaging and antifatigue agent, and antidote to jet lag and degenerative diseases (Garcia-Patterson et al., 1996). According to Olin (1996) melatonin is an FDA approved "orphan drug" prescribed for the treatment of circadian rhythm sleep disorders in blind patients.

You can't ask a fly to read, add, or operate heavy machinery," says Dr. Michael Young of Rockefeller University. But you can rely on Drosophila (fruit flies) to help fit all the pieces of the clock together, he notes. Dr. Young and other scientists think that, in flies and mammals, those pieces are a set of probably a dozen or so proteins.

It all started nearly 30 years ago, when scientists first stumbled upon mutant fruit flies with a permanent case of jet lag. Since then, NIGMS (National Institute of General Medical Sciences)-sponsored basic research has fueled the fire for a recent explosion of discoveries in the field of circadian rhythms.

So-called clock researchers now appreciate a striking evolutionary parsimony in the molecules and pathways used by seemingly every organism on the planet--including bacteria, fungi, plants, silk moths, mice, and humans--to establish a 24-hour physiologic day. Many of the protein parts of biological clocks in such widely diverse life forms appear remarkably alike.

Such conservation of function has clock scientists excited that they will be able to use fruit flies and other genetically tractable model organisms to dissect the mammalian biological clock, a feat that would lead to a better understanding of a host of human afflictions, including not only jet lag but also a variety of sleep disorders and mental illnesses.

In humans and other mammals, the body's "master clock" resides in a small sliver of brain tissue called the suprachiasmatic nucleus, or SCN. Light streaming into the eye of an animal sends a signal to the SCN, where 10,000 individual cellular pacemakers are housed. Within each of these SCN neurons, levels of a cast of protein characters--with names such as Period, Timeless, and Clock--rise and fall throughout the course of the day. Each protein helps keep cellular time by acting in a feedback loop in which the other proteins' production is shut off during certain parts of the day.

See also: Insomnia

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