By John R. Yarbrough, Ph.D.
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Also known as circadian dysrhythmia. Refers to a condition in which rapid travel across multiple time zones precipitates symptoms of sleep disturbance, fatigue or daytime sleepiness and loss of mental efficiency.
In layman’s terms, adds a DAN frequent flyer, "it means you are exhausted and spaced out after spending long periods of time in an airplane."
What is Jet Lag?
Travelers experience jet lag almost universally. Studies by airlines and major pharmaceutical companies, as well as a number of informal travel surveys, have found that 90-96 percent of travelers experience symptoms of jet lag. This condition can affect not only airline passengers, but seasoned travelers and long-haul flight crews as well.
For most people, the circadian sleep-wake cycle is normal — i.e., there is no other sleep-related disorder present — and the disruption occurs only when you’re traveling in a different time zone. For example, when divers from Los Angeles (Pacific Time Zone) vacation in Puerto Rico (Eastern Time Zone), they normally have no difficulty sleeping from 11 p.m. to 6 a.m. when at home. When they’re on holiday, however, they find that their "normal" bedtime of 11 p.m. is now only 8 p.m. local time.
Jet lag is usually less severe when people travel from east to west, as it is usually easier to delay sleep several hours rather than to force yourself to go to sleep earlier. This is especially true if it is still relatively early local time and the night is just getting started. Jet lag is not a concern if you’re traveling north and south within the same time zone; other aspects of traveling, however, (discussed shortly) may show similar symptoms, especially fatigue.
Jet lag is usually less problematic if travel involves only one or two time zones. Symptoms become increasingly severe as the number of zones crossed increases, with maximal disruption in the cycle experienced after traveling across more than eight time zones within a 24-hour period. Crossing the International Date Line may compound the problem by adding an element of temporal disorientation — e.g., leaving a dive site in Palau at 2:30 a.m. local time and arriving in Houston, after a 20-hour flight, at 7 a.m. that same day.
There is also some evidence that jet lag may be perceived as more severe in persons who already experience some other form of dyssomnia, or sleep disturbance. On the other hand, people who fall asleep easily, and those who are not usually on a strict "up at 6 a.m., coffee at 6:30, and work by 7:30 sharp" routine tend to have milder cases. It has also been noted that younger children tend to experience symptoms less severely, presumably because they are more adaptive and because their "schedules" are less rigid than those of adults.
Other symptoms of jet lag may include: poor concentration, slowed reflexes, indigestion, hunger at "odd" hours, increased irritability, dysphoria (a generalized state of unhappiness), headache, myalgias (muscle pains), and decreased resistance to infections or illness. Of all symptoms, however, dyssomnia persists longest. This symptom can last up to a week, and some sources suggest that sufferers may require up to one day for each time zone crossed in order to adjust.
Factors Complicating Jet Lag
Other factors can complicate the effects of jet lag, and while many are travel-related, others are not. Of these, pre-travel stress levels and pre-travel physical condition (which are, in themselves, related) are among the most important. Persons who are in good physical condition tend to rate symptoms as less severe.
Other travel-related factors influencing the effects of jet lag include:
- Dehydration — The air in aircraft cabins is relatively dry and recirculated, often leading to a feeling of "staleness." This contributes to dry skin and nasal irritation, which may also lead to headaches and susceptibility to colds, coughs or sore throat. During flight, the relative humidity in the cabin is similar to a dry summer climate or to being indoors in the wintertime, says Boeing Airline’s website. In this drier climate, the site notes, anyone can become dehydrated without enough liquid, so a rule of thumb often provided is to drink at least eight ounces of water for each hour of flight.
Another maxim advises that you don’t wait on your thirst. Drink plenty of low-sugar fluids and water — enough to keep your urine clear.
- ON-BOARD STRESSORS — These include crowding; uncomfortable seats; distractions that prevent you from working or sleeping; changes in cabin pressure, temperature extremes and increased noise.
Seasoned travelers sometimes request a window seat to avoid their neighbors’ disturbance when they go to the lavatory. They also note that sitting in an emergency exit row allows a traveler a few extra inches to stretch out. Some recommend the use of inflatable, U-shaped neck pillows to relieve stiffness, eyeshades and / or foam earplugs to reduce the noise of the baby crying two seats back. Others use a personal radio to play soft music or books on tape to mask the surrounding noise.
- INACTIVITY — As when you sit at a desk all day, the inactivity of sitting in a marginally comfortable aircraft seat for 16 hours can be one of the worst parts of overseas travel. Uncomfortable clothes and tight shoes can compound the problem. Further, the inactivity of travel increases the incidence of peripheral edema, which is swelling of the legs, ankles and feet. One 1988 study of 61 "sudden deaths" among long-distance travelers from the three previous years showed that 18 percent of the deaths occurred from embolisms in the lungs, believed secondary to a marked decrease in circulation.
To this end, some airlines provide travelers warm socks to be worn without shoes. This, in combination with in-seat exercises or walks about the cabin can help prevent edema or an even more serious disorder known as deep-vein thrombosis. Frequent travelers suggest that you take advantage of every opportunity to stretch out in empty seats or move about the cabin. During a stopover, you should try to get off the plane, move about and increase circulation.
- TRAVEL DIET — Diet, including alcohol and caffeine intake, have an impact on the perceived effects of jet lag. Caffeine is a stimulant with a half-life of between three to five hours. This means that about one half the original dose is eliminated from the body after this time. (Coffee typically contains 75-120 mg of caffeine per 8 oz. serving; caffeinated sodas, including most diet sodas, 34-71 mg per 12 oz. serving; hot cocoa, about 15 mg per 8 oz. serving; and milk chocolate, about 6 mg of caffeine per ounce.) This also means that the stimulant effects of caffeine may sometimes be felt for nine to 15 hours, thus impairing your ability to sleep later in the evening. Caffeine is also a diuretic, which tends to increase the effects of dehydration.
Similarly, alcohol has a diuretic effect, and can also impair natural sleep and worsen the effects of jet lag. Some sources even question the drinking of excess fruit juices when traveling, citing that excess sugar can negatively affect the sleep / wake cycle. Instead, water is the universal drink of choice.
As for diet, most sources advocate high-carbohydrate snacks, rather than the fatty and processed-sugar snacks and meals served on airlines. Many people tend to eat from boredom or to maintain alertness, thinking that sugary snacks will give them extra energy. High-sugar airline snacks may not be as nutritious, and they can lead to a feeling of stuffiness, especially when you’re sitting in an uncomfortable seat. Some sources recommend taking along foods such as PowerBars® or the type of snacks you usually eat at home.
Also, travelers should use caution when eating foods such as salads, cold meats and fish served on some foreign airlines, especially if they are not sure of their preparation. According to the World Health Organization, 50 percent of travelers experience gastrointestinal upset, and jet lag is considered a contributing factor.
Jet Lag Prevention
There are a number of commercial preventatives and "cures" available, including complicated jet lag "systems." However, to date no actual cures exist, and few empirical studies would rank any one method as preferable over another. Most sources recommend a multifaceted approach to the prevention and treatment of jet lag.
The traditional approach to jet lag prevention / treatment has involved adjustments to one’s sleep / wake schedule. Beginning at about three to five days prior to departure, local bedtime is gradually moved to what the accustomed bedtime would be at the destination. For example, if a diver were traveling eastward, he would try to go to sleep one hour earlier for each successive three nights prior to departure. If traveling westward, just the opposite would apply: he would try to stay awake one extra hour for each successive night prior to departure.
Most people find that it is easier to stay up longer and, if possible, sleep one hour longer the following morning than to go to sleep earlier — especially those who have trouble falling asleep in the first place. Thus westward flights are usually easier to adapt to than the converse. Traditionally, travelers have been advised to avoid trying to sleep on eastbound flights.
Building on this idea, some authorities have advocated phototherapy, the use of bright light to "reset" the circadian clock. Eastbound travelers should expose themselves to full-spectrum lighting for four to five hours in the mornings after arrival. This serves to turn back the circadian clock, allowing for an earlier awakening and alertness. Westbound travelers should expose themselves to bright lights for similar periods in the afternoons for three to five days to allow for a later bedtime and later waking the following day.
Some studies indicate that the use of knee-lights, or similar bright, full-spectrum lights placed behind the knees, may also be effective. Using lights in this area would allow the eastward traveler to use this technique earlier in the morning and remain asleep. However, this technique requires special equipment, and this means extra expense and additional luggage space.
Others assert that the primary reason for being on a dive holiday is to be outdoors. Thus, they advocate travelers use sunscreen and lie on the beach or deck of a boat. If a traveler must be indoors, the curtains should be open and the room lit as brightly as possible during the recommended periods of phototherapy. How do you know if you’re getting enough light? Use the light meter on a camera: Set the single-lens reflex (SLR) camera for ASA 50 film, 1/60 second at f:5.6. If the meter indicates that it is light enough to take a picture, the light is bright enough for phototherapy.
Melatonin, a hormone secreted by the pineal gland, has been suggested as a treatment for circadian dysrhythmia. It acts in the hypothalamus, in an area that mediates the sleep / wake cycle. Secreted mainly at night, it appears to have circadian phase-shifting properties that are the opposite of the effects of bright light. For example, melatonin administered in the afternoon advances the sleep / wake cycle, while a morning dosage produces a delay.
Claims have been made as to the antioxidant properties of melatonin, and it reportedly enhances the immune system and retards the growth of certain tumors. But there has been relatively little controlled research into the efficacy of melatonin, and the FDA lists it as an unregulated health food supplement.
Little consensus exists among experts as to the correct dosage for treating jet-lag symptoms. Tablets are manufactured in doses ranging from 300 mcg (0.3 mg.) to 10 mg. A number of preparations contain additional ingredients, such as B-vitamin complexes or folic acid (Bevitamel®). Some sources claim that 5 mg. about an hour before the desired bedtime is the optimal dosage (melatonin is found in the blood in amounts ranging from 13 picograms, or trillionths of a gram, per milliliter to a high of about 70 picograms per milliliter in the wee hours of the morning). Others claim that doses exceeding one gram have been tolerated without ill effect.
Melatonin, which is generally contraindicated in persons with seizures, autoimmune disorders or endocrine disorders, may decrease the effects of steroid medications. Pregnant or lactating women should consult their physician prior to use.
Note that some drugs may decrease the effectiveness of melatonin. These include aspirin, ibuprofen, medications for many cardiac conditions and hypertension, and prescription sleep medications, such as alprazolam (Xanax®). Alcohol, caffeine and nicotine also have inhibitory effects on melatonin.
A number of physicians remain concerned that the efficacies of melatonin and other treatment methods have not been sufficiently documented. They prefer instead to specifically target the complaint of insomnia with short-acting benzodiazepines, such as temazepam (Restoril®), or non-benzodiazepine soporifics such as zolpidem (Ambien®).
Prescription sleep medications are not generally indicated for long-term use. Interactions with other foods or drugs, especially alcohol, may occur. Of particular concern is the occurrence of "traveler’s amnesia," a condition in which travelers sometimes "lose" time, sometimes carrying on activities or waking up in their hotel rooms without remembering getting off the airplane. This reportedly occurs when the traveler is awakened before the drug has been eliminated from the system. Many physicians recommend not using prescription sleep medications on an overnight flight until such time as the traveler can get a full seven to eight hours of undisturbed sleep (i.e., at the hotel or back at home).
Some side effects of prescription sedative / hypnotics include next-day drowsiness, dizziness and lack of coordination. In rare cases, altered mental status, especially in combination with alcohol use, has been noted.
There are also a variety of over-the-counter (OTC) medications for insomnia, including diphenhydramine (Benadryl®, Sleepinal®, Sominex®, Nytol® and Tylenol PM®) or doxylamine (Unisom®). These are antihistamines, but have a side effect of sedation. They tend to dry out travelers’ nasal passages.
OTC preparations are not recommended for long-term use. They are also contraindicated for persons with glaucoma, peptic ulcer disease, chronic bronchial asthma, seizures, or those with difficulty urinating due to prostate enlargement. Taking a variety of OTC medications at the same time, or taking these preparations with prescription medications, is generally not advised.
In some persons these medications may have a paradoxical effect. Rather than producing the desired sedation, they may cause increased heart rate and restlessness. This can be especially troublesome when one feels mentally sluggish and at the same time "ready to crawl out of one’s skin."
To avoid prescription and OTC drugs, some groups advocate herbal or naturopathic remedies. Teas, extracts and capsules containing bitter orange, heather, hawthorn, Rauwolfia, valerian root, hops (and combination products, such as Alluna®, containing valerian with hops), are sometimes recommended to assist with problems related to insomnia. Other products, such as No-Jet-Lag® tablets, contain a variety of natural remedies to target specific complaints.
Some contend that relatively few controlled studies have investigated the efficacies of herbal remedies or their interactions with each other and with certain prescription medications. A physician should be informed that a person is using any herbal remedies with any type of medication. One should also know that there are no standards for the preparation or manufacturing of herbal remedies. Strengths and purity may vary from manufacturer to manufacturer, and there are no established "dosages" for most naturopathic remedies.
Fast / Feast: Dieting Your ‘Lag’ Away
Jet lag diets attempt to reset the body’s internal clock through a controlled schedule of feasting and fasting on alternate days. Dr. Charles F. Ehret of the Argonne National Laboratory developed the most popular in 1982. This diet is based on the theory that certain foods cause different bodily reactions. The regimen starts three days before departure.
On Day 1, feast on a high-protein breakfast and lunch, with a high-carbohydrate dinner. Limit caffeine consumption to between 3 and 5 p.m., local time. The following day, fast on light meals of fruit, soup or salads. Again, limit caffeine use. On Day 3, feast as on Day 1. On the day of departure, fast again until breakfast time at the destination. End the fast with a high-protein breakfast and remain active through the day. Take other meals at the usual destination times.
Combining a number of these "treatments," some hotels and resorts have added spa treatments to assist with jet lag symptoms. Some, such as the Oriental Hotel in Bangkok, offer hydrotherapy, a papaya body polish and massage, and gourmet cuisine to replace lost vitamins and nutrients. Other hotels offer "circadian suites," using blackout curtains and full-spectrum artificial lighting. Meals can be served any time of the day or night, such as a steak dinner at 7 a.m. As you can guess, these treatments are not cheap.
There may be other treatments for circadian dysrhythmia on the horizon. Within the past few years, researchers at the Baylor College of Medicine have identified a specific gene which appears to "turn on and off" throughout the day in a 24- to 25-hour cycle. They termed this the "rigui" gene, after an ancient Chinese sundial. Researchers hope that their studies will aid in the development of more specific and efficacious treatments for jet lag and other dyssomnias. Other researchers at the University of Utah are working with a similar gene discovered in 1999, with hopes of learning how to "reset" the circadian clock.
One simple suggestion in managing jet lag is to plan your post-flight schedule knowing that some symptoms, no matter how mild, will occur. Finally, you should always consult with your physician before attempting any self-treatments for jet lag, especially if you suffer from other medical conditions or if you’re taking prescription medications. Remember, it’s always OK to sit out a dive if you don’t feel up to going.
Tips for Minimizing Jet Lag
- Drink plenty of water during the flight. Consider carrying aboard your own bottled water.
- Avoid coffee, tea or caffeinated sodas.
- Avoid use of alcohol.
- Try carbohydrate snacks rather than airline foods.
- Wear comfortable clothing and shoes.
- Try to stretch or walk about the cabin every 90 minutes or so.
- Avoid trying to sleep on eastbound flights.
- Use foam earplugs or earphones to minimize noise.
- Set your watch to the time of the destination before you board the plane. If you take medication on a schedule, consider a watch with both an analog and digital face. This allows you to set both local and destination times and use alarms for medication times.
- Avoid driving, attending business meetings or activities requiring optimal alertness immediately upon arrival.
- If you don’t feel like diving one day, don’t. Fatigue or inability to concentrate can cause mistakes. Consider making the first dive a relaxing, no-demand "acclimatization" dive.
- Upon arrival, spend some time in the daylight as soon as possible.
- Upon arrival, limit your activities the first day or so. Relax. Remember that you are on holiday.
- Bezruchka, Stephen, MD, in Jong & McMullen, (1995), The Travel and Tropical Medicine Manual. Philadelphia: W. B. Saunders.
- World Health Organization, (1994), Safe Foods for Travelers: WHO’s Recommendation. WHO: Geneva.
- Bezruchka, Stephen, MD, in Jong & McMullen, (1995), The Travel and Tropical Medicine Manual. Philadelphia: W. B. Saunders.
- Reiter, Russel J and Robinson, Jo (1995). Melatonin. New York: Bantam.
- TravelASSIST Online
- Baylor College of Medicine, press release, 9/18/97.