- Time Zone Definition
- Direction of Travel
- Risk Factors
What is jet lag?
Jet lag, also called desynchronosis and flight fatigue, is a temporary disorder that causes fatigue, insomnia, and other symptoms as a result of air travel across multiple time zones. It is considered a circadian rhythm sleep disorder, which is a disruption of the internal circadian clock.
What are other symptoms and signs of jet lag?
Besides travel fatigue and insomnia, a jet lag sufferer may experience a number of physical and emotional symptoms, including anxiety, constipation, diarrhea, confusion, dehydration, headache, irritability, nausea, indigestion, difficulty concentrating, sweating, coordination problems, dizziness, daytime sleepiness, malaise (a general feeling of being unwell), and even memory loss. Some individuals report additional symptoms, such as heartbeat irregularities and increased susceptibility to illness.
Children and babies can also suffer the same jet lag symptoms as adults.
Generally, people do not need a medical evaluation for a diagnosis of jet lag. If you have traveled across several time zones and feel the symptoms associated with jet lag, you likely have it. If your symptoms of jet lag are severe, do not go away after a few days, or you have any other concerns, see a doctor.
How long does it take to recover from jet lag?
Recovering from jet lag depends on the number of time zones crossed while traveling. In general, the body will adjust to the new time zone at the rate of one or two time zones per day. For example, if you crossed six time zones, the body will typically adjust to this time change in three to five days.
Jet lag is temporary, so the prognosis is excellent and most people will recover within a few days.
Complications of jet lag are extremely rare. If a person has a preexisting heart condition, the stress of the disruption in the circadian rhythm, combined with the stress of travel, the high altitude, and immobility during flight may result in a heart attack. If the jet lag results in chronic sleep deprivation, stroke may occur in certain predisposed individuals.
What is a time zone?
The definition of a time zone is a geographical region which has the same time everywhere within it. The world has 24 time zones, one for each hour in the day. Each zone runs from north to south in strips that are approximately 1,000 miles (1,600 kilometers) wide. (The actual width of each zone varies to accommodate political and geographical boundaries.) As the earth rotates, dawn occurs at a set hour in one time zone, then an hour later in the time zone immediately to the west and so on through the 24-hour cycle. Thus, in the U.S., when it is 6 a.m. in the Eastern Time zone, it is 5 a.m. in the central zone, 4 a.m. in the mountain zone, and 3 a.m. in the Pacific zone.
What causes jet lag?
The cause of jet lag is the inability of the body of a traveler to immediately adjust to the time in a different zone. Thus, when a New Yorker arrives in Paris at midnight Paris time, his or her body continues to operate on New York time. As the body struggles to cope with the new schedule, temporary insomnia, fatigue, irritability, and an impaired ability to concentrate may set in. The changed bathroom schedule may cause constipation or diarrhea, and the brain may become confused and disoriented as it attempts to juggle schedules.
How does the body keep time?
Our bodies have a sort of internal biological clock that follows a 24-hour cycle, called a circadian rhythm. A tiny part of the brain called the hypothalamus acts like an alarm clock to activate various body functions such as hunger, thirst, and sleep. It also regulates body temperature, blood pressure, and the level of hormones and glucose in the bloodstream. To help the body tell the time of day, fibers in the optic nerve of the eye transmit perceptions of light and darkness to a timekeeping center within the hypothalamus. So, when the eye of an air traveler perceives dawn or dusk many hours earlier or later than usual, the hypothalamus may trigger activities that the rest of the body is not ready for, and jet lag occurs.
Does the direction of travel matter?
Yes. Travelers flying north or south in the same time zone typically experience the fewest problems because the time of day always remains the same as in the place where the flight originated. These travelers may experience discomfort, but this usually results from confinement in an airplane for a long time or from differences in climate, culture, and diet at the new location. Time differences do not play a role.
Travelers flying east, on the other hand, typically experience the most problems because they "lose" time. For example, on an international flight from Washington, D.C., to Mecca, Saudi Arabia, a traveler loses eight hours. Meals, sleep, bowel habits, and other daily routines are all pushed ahead eight hours.
Travelers flying west "gain" time and usually have an easier time adjusting than eastward travelers. However, they too experience symptoms of jet lag after landing because they still must adjust to a different schedule.
Do the symptoms of jet lag vary in intensity?
Yes. People flying across only one or two time zones may be able to adjust without noticeable effects of the time change. Those flying across three or more time zones will likely develop noticeable symptoms of jet lag. Generally, the intensity of symptoms varies in relation to the number of time zones crossed and the direction of travel. People also vary in their susceptibility to jet lag symptoms and the severity of the symptoms.
What are risk factors for jet lag?
The main cause of jet lag is travel across different time zones. However, there are certain risk factors that may result in symptoms being more severe or longer-lasting.
- Travel across three or more time zones: Most people can adjust rapidly to a one or two time zone change. Three or more may cause more noticeable symptoms of jet lag.
- Flying east: As stated previously, travel from west to east causes travelers to "lose" time, and this can be a more difficult adjustment.
- Age: Older adults may recover from jet lag more slowly.
- Frequent travel: Pilots, flight attendants, and frequent business travelers who are constantly in different time zones may have difficulty adjusting.
- Preexisting conditions: Preexisting sleep deprivation, stress, and poor sleep habits prior to travel can exacerbate jet lag symptoms.
- Flight conditions: The monotony of travel, immobility and cramped seating, airline food, altitude, and cabin pressure can impact jet lag symptoms.
- Alcohol use: Overconsumption of alcohol during long flights can also worsen the symptoms of jet lag.
Are there any remedies for jet lag? Is it possible to prevent jet lag?
There are several home remedies that can help with prevention of jet lag and easier recovery from the symptoms. The following are 12 tips to help travelers to avoid or to minimize the effects of jet lag.
Tip 1: Stay in shape
If you are in good physical condition, stay that way. In other words, long before you embark, continue to exercise, eat right, and get plenty of rest. Your physical stamina and conditioning will enable you to cope better after you land. If you are not physically fit, or have a poor diet, begin shaping up and eating right several weeks before your trip.
Tip 2: Get medical advice
If you have a medical condition that requires monitoring (such as diabetes or heart disease), consult your physician well in advance of your departure to plan a coping strategy that includes medication schedules and doctor's appointments, if necessary, in the destination time zone.
Tip 3: Change your schedule
If your stay in the destination time zone will last more than a few days, begin adjusting your body to the new time zone before you leave. For example, if you are traveling from the U.S. to Europe for a one-month vacation, set your daily routine back an hour or more three to four weeks before departure. Then, set it back another hour the following week and the week after that. Easing into the new schedule gradually in familiar surroundings will save your body the shock of adjusting all at once.
If you are traveling east, try going to sleep earlier and getting up and out into the early morning sun. If traveling west, try to get at least an hour's worth of sunlight as soon as possible after reaching your destination.
There are online jet lag calculators that can help you figure out how much and when to reset your sleep schedule to help you adjust to a time change before you depart.
Tip 4: Avoid alcohol
Do not drink alcoholic beverages the day before your flight, during your flight, or the day after your flight. These beverages can cause dehydration, disrupt sleeping schedules, and trigger nausea and general discomfort.
Tip 5: Avoid caffeine
Likewise, do not drink caffeinated beverages before, during, or just after the flight. Caffeine can also cause dehydration and disrupt sleeping schedules. What's more, caffeine can rattle your nerves and intensify any travel anxiety you may already be feeling.
Tip 6: Drink water
Drink plenty of water, especially during the flight, to counteract the effects of the dry atmosphere inside the plane. Take your own extra water aboard the airplane if allowed.
Tip 7: Move around on the plane
While seated during your flight, exercise your legs from time to time. Move them up and down and back and forth. Bend your knees. Stand up and sit down. Every hour or two, get up and walk around. Do not take sleeping pills, and do not nap for more than an hour at a time.
These measures have a twofold purpose. First, they reduce your risk of developing a blood clot in the legs. Research shows that long periods of sitting can slow blood movement in and to the legs, thereby increasing the risk of a clot. The seat is partly to blame. It presses against the veins in the leg, restricting blood flow. Inactivity also plays a role. It slows the movement of blood through veins. If a clot forms, it sometimes breaks loose and travels to the lungs (known as pulmonary embolism), lodges in an artery, and inhibits blood flow. The victim may experience pain and breathing problems and cough up blood. If the clot is large, the victim could die. Second, remaining active, even in a small way, revitalizes and refreshes your body, wards off stiffness, and promotes mental alertness which can ease the symptoms of jet lag.
Tip 8: Break up your trip
On long flights traveling across eight, 10, or even 12 time zones, break up your trip, if feasible, with a stay in a city about halfway to your destination. For example, if you are traveling from New York to Bombay, India, schedule a stopover of a few days in Dublin or Paris. (At noon in New York, it is 5 p.m. in Dublin, 6 p.m. in Paris, and 10:30 p.m. in Bombay.)
Tip 9: Wear comfortable shoes and clothes
On a long trip, how you feel is more important than how you look. Wear comfortable clothes and shoes. Avoid items that pinch, restrict, or chafe. When selecting your trip outfit, keep in mind the climate in your destination time zone. Dress for your destination.
Tip 10: Check your accommodations
Upon arrival, if you are staying at a hotel, check to see that beds and bathroom facilities are satisfactory and that cooling and heating systems are in good working order. If the room is unsuitable, ask for another.
Tip 11: Adapt to the local schedule
The sooner you adapt to the local schedule, the quicker your body will adjust. Therefore, if you arrive at noon local time (but 6 a.m. your time), eat lunch, not breakfast. During the day, expose your body to sunlight by taking walks or sitting in outdoor cafés. The sunlight will cue your hypothalamus to reduce the production of sleep-inducing melatonin during the day, thereby initiating the process of resetting your internal clock.
When traveling with children and babies, try to get them on the local schedule as well. When traveling east (you will lose time), try to keep the child awake until the local bedtime. If traveling west when you will gain time, wake your child up at the local time.
Tip 12: Use sleeping medications wisely -- or not at all
Try to establish sleeping patterns without resorting to pills. However, if you have difficulty sleeping on the first two or three nights, it's OK to take a mild sedative if your physician has prescribed one. But wean yourself off the sedative as soon as possible. Otherwise, it could become habit-forming.
Sleep medications are not recommended for children.
What is the treatment for jet lag?
The best way to treat jet lag is to take measures to prevent it. But you may still feel jet lagged when traveling across many time zones, even with some preventive measures. Treatment to cure jet lag involves some of the home remedies discussed.
When you arrive at your destination, try to adapt to the local schedule as soon as possible. For example, if you arrive at 6 p.m. local time (but noon your time), eat dinner, not lunch. If your normal bedtime at home is 11 p.m., go to bed at 11 p.m. local time (even if it's only 5 p.m. at home). Get as much exposure to sunshine during the day as possible to help reset your internal body clock.
Once you arrive at your destination, a small dose of caffeine, such as from your morning coffee, may help jolt you awake for a few hours. Caffeine is best reserved for the early part of the day because it can keep you awake at night if taken too late.
Are there effective medications for jet lag? What is the role of melatonin in jet lag?
There are no specific medications for jet lag, only medications that may help you get to sleep more easily when you reach your destination, or that remedy some symptoms of jet lag.
Melatonin is a hormone that plays a key role in body rhythms and jet lag. After the sun sets, the eyes perceive darkness and alert the hypothalamus to begin releasing melatonin, which promotes sleep. Conversely, when the eyes perceive sunlight, they tell the hypothalamus to withhold melatonin production. However, the hypothalamus cannot readjust its schedule instantly; it takes several days.
A dose of melatonin that is between 0.3 mg-5 mg may be taken on the first day you travel at the time you go to sleep at your destination, and for a few days, if needed. Melatonin seems to be most effective when crossing five or more time zones, or traveling east. Melatonin should only be taken by adults. Do not drink alcohol when taking melatonin. Consult a doctor if you plan on taking melatonin.
Prescription or over-the-counter (OTC) sleeping pills may help you reset your body clock to the time at your destination. Try not to use them if possible, but if your doctor has prescribed sleep medication, it may be taken if needed for up to two or three nights. Try not to take it for longer, as these medications can be habit-forming.
OTC sleep aids include
Prescription sleep medications include the following:
Health Solutions From Our Sponsors
Goldstein, Cathy A. "Jet Lag." UpToDate.com. October 2019. <http://www.uptodate.com/contents/jet-lag>.
"Melatonin and Sleep." National Sleep Foundation. <http://www.sleepfoundation.org/article/sleep-topics/melatonin-and-sleep>.
"Sleep and Circadian Rhythm Disorders." WebMD.com. Nov. 5, 2019. <https://www.webmd.com/sleep-disorders/guide/circadian-rhythm-disorders-cause>.
Tuttle, Troy, Asif Ali, David Filsoof, and John Higgins. "High Altitude, Air Travel, and Heart Disease." UpToDate.com. October 2019. <http://www.uptodate.com/contents/high-altitude-air-travel-and-heart-disease?source=search_result&search=jet+lag+heart+attack&selectedTitle=1~150>.
United States. National Institute of General Medical Sciences. "Circadian Rhythms Fact Sheet." August 2017. <https://www.nigms.nih.gov/education/pages/factsheet_circadianrhythms.aspx>.