Jet lag results from a mismatch between a person’s circadian (24-hour) rhythms and the time of day in the new time zone. When establishing risk, clinicians should first determine how many time zones the traveler will cross and what the discrepancy will be between time of day at home and at the destination. During the first few days after a flight to a new time zone, a person’s circadian rhythms are still “anchored” to time of day at home. Rhythms then adjust gradually to the new time zone. A useful web-based tool for world time zone travel information can be found at www.timeanddate.com/worldclock/converter.html. If ≤3 time zones are being crossed, any symptoms such as tiredness are likely due to travel fatigue rather than significant jet lag, and will soon abate.

Many people traveling >3 time zones away for a vacation accept the risk of jet lag as a transient and mild inconvenience, while other people who are traveling on business or to compete in athletic events desire clear advice on prophylactic measures and treatments. If ≤2 days are spent in the new time zone, some people may prefer to anchor their sleep-wake schedule to time of day at home as much as is practical. Thereby, the total “burden” of jet lag resulting from the short round trip is minimized.

The symptomatology of jet lag can often be difficult to define because of variation between people, but also because the same person can experience different symptoms after each flight. Jet-lagged travelers typically experience ≥1 of the following symptoms after a flight across >3 time zones:

• Poor sleep, including difficulty initiating sleep at the usual time of night (after eastward flights), early awakening (after westward flights), and fractionated sleep (after flights in either direction)
• Poor performance in physical and mental tasks during the new daytime
• Negative feelings such as fatigue, headache, irritability, anxiety, inability to concentrate, and depression
• Gastrointestinal disturbances and decreased interest in, and enjoyment of, meals
• Symptoms are difficult to distinguish from the general fatigue resulting from international travel itself, as well as from other travel factors such as the hypoxia in the aircraft cabin.

Since light and social contacts influence the timing of internal circadian rhythms, a traveler who is staying in the time zone for >2 days should try to follow the local people’s sleep–wake habits as much as possible and as quickly as possible. This approach can be supplemented with the following information on specific treatments.

Light

Exposure to bright light can advance or delay human circadian rhythms depending on when it is received relative to a person’s body clock time. Consequently, schedules have been formulated for proposed “good” and “bad” times for exposure to light after arrival in a new time zone.

After flights that cross a large number of time zones, the proposed best circadian time for exposure to light immediately after the flight may actually be when it is still dark in the new time zone, which raises the question of whether exposure to supplementary light from a “light box” is helpful. Unfortunately, to date, only 1 small randomized controlled trial on supplementary bright light for reducing jet lag has been conducted. No clinically relevant effects of supplementary light on jet lag symptoms were detected after a flight across 5 time zones going west.

Diet and Physical Activity

Most dietary interventions have not been found to reduce jet lag symptoms. In a recent study, long-haul flight crews showed a small improvement in their general subjective rating of jet lag, but not the separate symptoms of jet lag or alertness, on their days off work when they adopted more regular meal times. Because gastrointestinal disturbance is a common symptom, smaller meals before and during the flight might be better tolerated than larger meals. Caffeine and physical activity may be used strategically at the destination to ameliorate any daytime sleepiness, but little evidence indicates that these interventions reduce overall feelings of jet lag. Any purported treatments that are underpinned by homeopathy, aromatherapy, and acupressure have no scientific basis.

Hypnotic Medications

Prescription medications like temazepam, zolpidem, or zopiclone may reduce sleep loss during and after travel but do not necessarily help resynchronize circadian rhythms or improve overall jet lag symptoms. If indicated, the lowest effective dose of a short-to medium-acting compound should be prescribed for the initial few days, bearing in mind the adverse effects of these drugs.

Taking hypnotics during a flight should be considered with caution because the resulting immobility could increase the risk of deep vein thrombosis. Alcohol should not be used by travelers as a sleep aid, because it disrupts sleep and can provoke obstructive sleep apnea.

Melatonin and Melatonin-Receptor Analogs

Melatonin is secreted at night by the pineal gland and is probably the most well-known treatment for jet lag. Melatonin delays circadian rhythms when taken during the rising phase of body temperature (usually the morning) and advances rhythms when ingested during the falling phase of body temperature (usually the evening). These effects are opposite to those of bright light.

The instructions on most melatonin products advise travelers to take it before nocturnal sleep in the new time zone, irrespective of number of time zones crossed or direction of travel. Studies published in the mid-1980s indicated a substantial benefit of melatonin (just before sleep) for reducing overall feelings of jet lag after flights. However, subsequent larger studies did not replicate the earlier findings.

Melatonin is considered a dietary supplement in the United States and is not regulated by the Food and Drug Administration. Therefore, the advertised concentration of melatonin has not been confirmed for most melatonin products on the market, and the presence of contaminants in the product cannot be ruled out.

Ramelteon, a melatonin-receptor agonist, is an FDA-approved treatment for insomnia. A dose of 1 mg taken just before bedtime can decrease sleep onset latency after eastward travel across 5 time zones. Higher doses do not seem to lead to further improvements, and the effects of the medication on other symptoms of jet lag and the timing of circadian rhythms are not as clear.

Combination Treatments

Multiple therapies to decrease jet lag symptoms may be combined into treatment packages. Although marginal gains from multiple treatments may aggregate, evidence from robust randomized controlled trials is lacking for most of these treatment packages. One treatment package offering tailored advice via a mobile application was piloted to be used over several months of frequent flying. Participants reported reduced fatigue compared with the comparator group and improved aspects of health-related behavior such as physical activity, snacking, and sleep quality but not other measures of sleep (latency, duration, use of sleep-related medication).

In conclusion, there is still no “cure” for jet lag. Counseling should focus on the factors that are known, from laboratory simulations, to alter circadian timing. Nevertheless, more randomized controlled trials of treatments prescribed before, during, or after transmeridian flights are needed before the clinician can provide robust, evidence-based advice.

Complementary approaches that have been suggested for jet lag or other sleep problems include the dietary supplement melatonin; relaxation techniques and other mind and body practices; aromatherapy; and herbs such as chamomile, kava, and valerian.

Melatonin

Some evidence suggests that melatonin supplements may help with sleep problems caused by jet lag in people traveling either east or west.

Relaxation Techniques

Relaxation techniques, such as progressive relaxation, and other mind and body practices, such as mindfulness-based stress reduction, may help with insomnia, but it has not been established if they are effective for jet lag.

Aromatherapy and Herbs

There is very little evidence that aromatherapy or the herbs chamomile or valerian help with insomnia.

Another herb, kava, is also promoted for sleep but good research on its effectiveness is lacking.

Safety

• Melatonin is sold as a dietary supplement; dietary supplements are regulated less strictly than drugs. The amounts of ingredients in dietary supplements may vary, and product contamination is a potential concern.
• A 2017 analysis of melatonin supplements sold in Canada found that their actual melatonin content ranged from –83% to +478% of the labeled content and that there was substantial lot-to-lot variation. Also, 26% of products contained serotonin as a contaminant.
• Melatonin supplements appear to be safe for most people when used short-term; less is known about their long-term safety. The absence of long-term studies, however, makes it challenging to know with certainty the safety and tolerability of melatonin with continued use.
• In a 2019 systematic review of mostly short-term trials of melatonin for sleep problems, the most frequently reported adverse events were daytime sleepiness (1.66%), headache (0.74%), other sleep-related adverse events (0.74%), dizziness (0.74%), and hypothermia (0.62%). Almost all adverse events were considered mild or moderate in severity and tended to resolve either spontaneously or after discontinuing treatment.
• People with epilepsy or who take an oral anticoagulant should never use melatonin without medical supervision.
• Travelers should not take melatonin early in the day because it can cause sleepiness and delay adaptation to local time.
• Relaxation techniques are safe for most people.
• Significant side effects from aromatherapy and herbs are uncommon, but chamomile can cause allergic reactions and kava supplements have been linked to a risk of severe liver damage.

Jet lag usually occurs when a traveler crosses at least five time zones. Follow these tips to avoid severe jet lag:

• Before travel, reduce jet lag by exposing yourself to light in the evening hours if you will be traveling west or to light in the early morning hours if you travel east.
• On arrival, expose yourself to bright light in the morning to help you adjust.
• Before traveling west, begin to reset the body clock by going to bed 1–2 hours later than usual for a few days. If traveling east, go to bed 1–2 hours earlier. Also, change the time of your meals to coincide with your changes in sleeping habits.
• During travel, drink plenty of fluids, avoid excess alcohol, eat healthy, and exercise.
• On arrival, take 20–30 minute nap to increase energy, if needed. Remember that longer naps can make it harder to sleep at night.
• On arrival, adjust both eating and sleeping schedules to the local time as soon as possible.
• Allow time for rest before beginning a new work routine. Do not schedule business meetings or other work on arrival.

Note: The FDA does not regulate melatonin and its safety is not established.

Jet lag is caused by a mismatch between a person’s normal daily rhythms and a new time zone. It is a temporary sleep problem that usually occurs when you travel across more than three time zones but can affect anyone who travels across multiple time zones. Jet lag can affect your mood, your ability to concentrate, and your physical and mental performance. Fortunately, you can take steps to minimize the effects of jet lag.

Before Travel

A few days before you travel, you can begin adjusting your body’s natural clock to the time zone at your destination. Depending on where you are traveling you may want to adjust your sleep patterns to get used to the time change:

• If traveling west, go to bed an hour or two later than usual
• If traveling east, go to bed an hour or two earlier than usual.

Consider scheduling travel to arrive at your destination at least 2 days before any important events, to give your body time to adjust.

Stomach aches and other stomach problems are a symptom of jet lag; eating smaller meals just before travel may help. If you struggle with jet lag, talk to your doctor about taking medicine or other sleep aids to help you sleep.

During Travel

If you are traveling to a time zone that is more than 3 hours different than your normal time zone you should follow the sleep and waking routines of your destination when you arrive. It might help to stay in well-lit areas at your destination during the day. Take any medicine or sleep aids as directed by your healthcare provider to help you sleep at night.

Other steps you can take to help you adjust to the new time and avoid jet lag symptoms:

• Eat small meals to avoid stomach aches or other problems.
• Avoid alcohol as it disrupts sleep.
• Use caffeine and exercise strategically, these may help you stay alert throughout the day, but you should avoid these in the evening.
• Drink plenty of water.
• If you are sleepy during the day, take short naps, no more than 15-20 minutes, to help you feel better during the day, yet still sleep at night.

A combination of these steps will help you overcome jet lag more quickly.