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Travelers at Beijing Capital International airport can attest to jet lag being a discrepancy between our internal biological clock and the local time zone.(Image credit: AFP via Getty Images)Share this article 0Join the conversationFollow usAdd us as a preferred source on GoogleSubscribe to our newsletter
Most individuals undertaking long-distance journeys have experienced the disorientation of switching time zones, feeling overly sleepy during the day while struggling to find slumber at night.
Jet lag frequently arises when individuals cross multiple time zones. The majority encounter greater difficulty when traveling eastward, as our internal clocks naturally run slightly longer than 24 hours. “It’s a little bit harder to shift earlier,” Helen Burgess, a professor at the University of Michigan’s Sleep and Circadian Research Laboratory, informed Live Science.
So, what transpires within our bodies during jet lag, and can it be averted?
What is jetlag?
Jet lag signifies a misalignment between our internal body clock and the prevailing time zone.
The phrase “jet lag” was first used in a 1966 Los Angeles Times article, where journalist Horace Sutton depicted the sensations experienced by frequent flyers on long journeys as being “not unakin to a hangover.”
“He said, at the time, that jet lag derives from the simple fact that jets travel so fast they leave your body rhythms behind,” Dr. Charles Czeisler, a professor of sleep medicine at Harvard Medical School, explained to Live Science. Prior to the advent of air travel, people traversed land or sea at a much slower pace, preventing their circadian rhythms from falling out of sync.
Jet lag is the body’s natural consequence of traversing different time zones. “If the circadian system is working correctly, you should have a problem with jet lag,” Czeisler stated.
However, certain groups — such as the elderly, frequent travelers, or individuals with mood or sleep disorders — may be more prone to experiencing its effects.
Two travelers resting in the passenger terminal at Heathrow Airport, London.
(Image credit: Malcolm Clarke / Stringer via Getty Images)
While jet lag might appear insignificant, even mild cases can lead to considerable health consequences. When clocks advance, effectively creating an hour of jet lag, there is an observed increase in fatal automobile accidents, according to Czeisler. Operating a vehicle immediately after a long flight poses a risk, as sleep deprivation is a recognized contributor to traffic collisions. In fact, road incidents are the primary cause of non-natural fatalities among U.S. citizens traveling internationally.
Furthermore, disruptions to circadian rhythms can even “flip people into mania or depression,” Czeisler commented. Data from one investigation indicated that over a two-year period, 186 individuals were admitted to a psychiatric facility from Heathrow Airport due to jet-lag-related mental health issues, including depression and hypomania (a less severe, shorter-duration form of mania). Another study suggested that persistent jet lag might elevate the likelihood of developing neurological conditions.
Minimizing jet lag
The most effective method for adapting to a new time zone involves light exposure. “Light is the strongest signal that shifts the timing of the clock,” Burgess asserted.
However, the timing of this exposure is crucial: light encountered at an inappropriate moment can shift your internal clock in the wrong direction, prolonging the effects of jet lag.
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Approximately two to three hours before your typical waking time, your internal clock transitions from perceiving light as evening illumination, inducing sleepiness, to recognizing it as morning light, which promotes wakefulness.
“Light before the crossover point will shift you later, and light after the crossover point will shift you earlier,” Burgess explained. This is why taking a nap is not always the optimal solution.
If you typically awaken at 6 a.m., your critical transition point would be around 3 a.m. Consequently, if you travel to a time zone six hours ahead and arrive at 7 a.m., this would correspond to approximately 1 a.m. on your internal clock, which remains synchronized to your original time zone. Therefore, your body interprets all the morning light it receives upon arrival and during the security process as evening light, prompting it to wake you again and delay your internal clock.
Understanding when to expose yourself to light requires foresight. To receive light when beneficial, venture outdoors, utilize specialized light boxes, or employ wearable light therapy devices. To avoid light that might push your clock in the undesirable direction, take naps, remain indoors, or wear sunglasses or eyewear designed to block blue light within a specific spectrum (460 to 480 nanometers).
To mitigate the effects of jet lag, maintain hydration, limit alcohol consumption, and be conscious of excessive caffeine intake — “perhaps just one cup of coffee” at strategic moments, Burgess advised, noting that caffeine has a prolonged half-life and can persist in the body, hindering sleep — and try to align with local meal times as soon as possible. Some individuals might also consult healthcare professionals regarding the appropriateness of melatonin for their needs.
Jet lag can be preempted by adjusting your body clock to the new time zone prior to arrival. “On average, we can only shift the clock earlier by about an hour and a half a day,” Burgess noted.
For instance, to acclimatize to a time zone ten hours ahead, you would need to commence altering your light exposure schedules a week in advance of your flight. For example, if you normally sleep between 11 p.m. and 6 a.m., your goal would be to shift towards retiring at 9 a.m. and waking at 4 p.m. — a schedule that is impractical for the majority of individuals.
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This strategy is effective, Burgess confirmed, but when she personally tested it, she felt disconnected from her surroundings, as most people were asleep during her active hours. “I just felt really, really isolated,” she recounted.
While this approach is not feasible for most, it would prevent the experience of jet lag symptoms due to the gradual adjustment of your sleep schedule towards the new time zone. “People do not experience jetlag symptoms because everything is being moved slowly together,” Burgess stated, rather than being “yanked apart” by a single flight.
If you prefer not to adopt a nocturnal schedule before departing, try subtly shifting your own schedule by about an hour earlier each day for a few days. Essentially, if fully transitioning to the new time zone before departure seems too demanding, making even minor adjustments towards it before arrival will still prove beneficial. “It can make a huge difference,” particularly for those flying eastward, Burgess emphasized. “Take the five or 10 minutes to plan it out, and that’s going to really help.”
