You step off the plane, ready to explore and enjoy every minute of your long-awaited dream vacation. But there was one thing you didn’t fully consider when planning your trip: the exhaustion that would set in. 

This is the frustrating reality of jet lag, a common travel woe that can turn even the most exciting trips into a struggle to stay awake and alert. Jet lag can also cause problems with falling asleep, concentration, mood, and digestion.1

But whether you're a frequent flyer or embarking on a once-in-a-lifetime journey, understanding jet lag and learning how to combat it can help you minimize its effects and enjoy trips more fully.

The inner workings of jet lag

Jet lag occurs when a person travels rapidly across two or more time zones, leading to a misalignment among circadian rhythms, the body’s internal clocks, and the time at a destination. Circadian rhythms operate on roughly a 24-hour cycle, regulating sleep, wakefulness, hormone production, and other physiological processes.2,3 

Environmental cues strongly influence circadian rhythms, which help synchronize the body’s internal clock to the external world. Light has the most influence on circadian rhythms.2,3 

Light enters the eyes and sends signals to the suprachiasmatic nucleus, a pacemaker for circadian rhythms located in the hypothalamus portion of the brain.3 When light dims in the evening, it triggers the pineal gland to produce melatonin, a hormone that promotes sleep. This begins about two hours before bedtime.1 The same time that melatonin production is ramping up, core body temperature (CBT) begins to drop, another internal signal that it’s time to sleep.2,3 

With dawn and an increase in light, melatonin levels drop while cortisol and other hormones naturally increase along with CBT, telling the body it’s time to wake up. During the rest of the day, your melatonin level stays low to keep you alert until the process starts again.2

Travel can throw a wrench into these natural cycles. When you travel across several time zones, and light cues shift, the phases that prepare the body for falling asleep and waking up are thrown off course. The more time zones you cross, the bigger the effect.2

East vs. west travel and other factors that impact jet lag

If you’ve flown east and west across multiple time zones, then you know that westward travel seems less punishing on the body than eastward. There’s a reason for that.1

When heading west, you’re delaying your circadian rhythms, meaning your body needs to shift its internal clock backward to align with the local time. For a trip from New York to San Francisco, for example, your body needs to turn back its internal clock by three hours. When you fly east from San Franciso to New York, your body must move its internal clock ahead by three hours.1

Although it seems counterintuitive, traveling from the east coast to the west coast and extending your day by three hours is easier on your circadian rhythms. That’s because circadian rhythms aren’t perfectly aligned with the 24-hour day. For most people, they run slightly longer at about 25 hours.4 This slight deviation makes it easier to travel west because prolonging the day is “going with” your internal clock.2 Travelling eastward, however, runs in direct opposition to the body clock.

Other factors influencing jet lag include your age and timing of the flight. Older adults typically experience more pronounced jet lag symptoms. Flying at odd times, such as overnight, tends to be the most disruptive. However, symptoms and severity differ from person to person.2

Sometimes, jet lag is confused with travel fatigue. Although the two conditions have similar symptoms, travel fatigue isn’t dependent on crossing time zones. Instead, it can occur when traveling in any direction and is linked to factors such as dehydration, cramped airplane conditions, and the overall stress of travel. A good night’s sleep can often resolve symptoms of travel fatigue.1  

Relieving jet lag

Although jet lag can't be entirely avoided, your internal clock will eventually adjust to the new time zone. This occurs at approximately the rate of one time zone per day for eastward travel and one and a half time zones per day for westward travel. If you’re traveling from New York to London, it might take up to five days for your circadian rhythms to recalibrate.2 There are strategies you can try before your trip and after you land that might alleviate your jet lag symptoms and speed up the adjustment process. 

Before you fly. If you’re headed west, three or four days before you embark, schedule your bedtime and wake-up time a half-hour to an hour later each day to maximize evening light exposure and minimize morning light exposure.1,3

If you’re flying east, you can prepare your body for the time change by adjusting your bedtime and wake-up time by a half-hour to an hour earlier each day.1,3

After you’ve landed. Try these tactics to help your body’s circadian rhythm adjust to the time change at your destination.1

  1. Use light to your advantage. Light exposure is one of the most effective ways to reset your clock. In general, after eastward travel, seek morning light exposure without wearing sunglasses to advance your internal clock. Expose yourself to evening light after westward travel to help shift your clock backward.3 
  2. Eat well. Maintaining a healthy, well-balanced diet and eating meals on local time is important, but certain macronutrients may also help with jet lag. A protein-rich meal can help with alertness, while a carbohydrate-focused meal can promote drowsiness.4 Avoid alcohol and use caffeine sparingly to prevent disturbances in sleep. Stay hydrated because dehydration can worsen jet lag symptoms.4,5 
  3. Exercise. Some evidence suggests that vigorous exercise after arriving at a destination might relieve jet lag symptoms, as long as it’s not too close to bedtime. Exercising can arouse the central nervous system, making you feel more alert, but promote more restful sleep if done away from bedtime.1.3,6 
  4. Try a melatonin supplement. Melatonin supplementation offers a two-pronged benefit for combatting jet lag-related sleep disturbances: It can help adjust circadian rhythms and promote drowsiness.*1,4 Take melatonin close to bedtime in your new time zone. Melatonin for westward trips usually isn’t necessary unless you’re traveling across 12 or more time zones.1 Studies suggest that 3 mg of melatonin offers the most consistent benefit,* and immediate-release supplements are more effective than delayed-release products. If you take other medications, check with your health-care professional to ensure melatonin doesn’t cause an interaction.1,3  
  5. Prep your sleep environment. Keep your sleep space cool, dark, and quiet. Use earplugs, eye masks, and other sleep aids to create a comfortable sleeping environment, especially if you need to sleep during daylight hours.4

Ultimately, while jet lag is inevitable in long-distance travel, it doesn’t have to derail your trip. With careful planning and the right interventions, you can reduce its impact, leaving you to focus on exploring your destination and getting the most out of the journey.

A word from Thorne

Thorne offers melatonin in 3-mg capsules. In addition, some research indicates that vitamin B12 in the form of methylcobalamin (an active, tissue-ready form of vitamin B12) modulates melatonin secretion and helps normalize circadian rhythms.*

References

  1. Goldstein CA. Jet lag. UpToDate. https://www.uptodate.com/contents/jet-lag. [Accessed July 12, 2024.]
  2. Ambesh P, Shetty V, Ambesh S, et al. Jet lag: Heuristics and therapeutics. J Family Med Prim Care. 2018;7(3):507-510.
  3. Roach GD, Sargent C. Interventions to minimize jet lag after westward and eastward flight. Front Physiol. 2019;10:927. 
  4. Janse van Rensburg DC, Fowler P, Racinais S. Practical tips to manage travel fatigue and jet lag in athletes. Br J Sports Med. 2021;55:821-822.
  5. Janse van Rensburg DC, Jansen van Rensburg A, Fowler PM, et al. Managing travel fatigue and jet lag in athletes: A review and consensus statement. Sports Med. 2021;51(10):2029-2050. 
  6. Keystone JS, et al., eds. Jet lag. In: Travel Medicine. 4th ed. Elsevier; 2019. https://www.clinicalkey.com. [Accessed July 12, 2024.]