Carlos Solis
Jet lag is a mismatch between our and the local time. The term “jet lag” first appeared in a 1966 Los Angeles Times article, where reporter Horace Sutton described travelers’ feelings as “like a hangover.”
As Charles Czeisler, a professor of sleep medicine at Harvard Medical School, explains, people used to travel more slowly—by car or ship—so slower travel didn’t throw their off. When planes cross many time zones in a few hours, the body can’t adjust fast enough.
Why It’s Harder to Fly East
Our internal clock is usually a little longer than 24 hours, so it’s easier to delay your wake time than to move it earlier. “Shifting to an earlier time is a bit tougher,” says Helen Burgess of the Sleep and Circadian Rhythms Lab at the University of Michigan.
How Jet Lag Affects Your Health
Even small disruptions to circadian rhythms can have serious effects. Czeisler says moving clocks forward (an effect equivalent to one hour of jet lag) has been linked to a rise in fatal car crashes. Lack of sleep after a long-haul flight makes driving especially dangerous—road crashes are a leading cause of unnatural death among Americans traveling abroad.
Shifts in the circadian system can also affect mental health, sometimes pushing people into mania or depression. One study found that over two years, 186 people were admitted to hospitals from Heathrow with conditions associated with jet lag (depression and hypomania). Other studies suggest chronic jet lag may raise the risk of neurological disorders.
How to Minimize Jet Lag Symptoms
The single most effective way to adapt to a new time zone is to manage light exposure. “Light is the strongest cue that shifts the clock,” Burgess says. Timing matters: light at the wrong moment can push your clock the opposite way and prolong jet lag.
Your body has a transition point about 2–3 hours before your usual wake time: light before that point reads as evening (it promotes sleepiness), while light after it reads as morning (it wakes you). “Light before the transition point shifts you later, and light after it shifts you earlier,” Burgess explains. For that reason, a short daytime nap doesn’t always help.
Example: if you normally wake at 6:00 a.m., your transition point will be around 3:00 a.m. If you fly east across six time zones and land at 7:00 a.m. local time, your internal clock will read roughly 1:00 a.m., so the destination’s morning light will register as evening and push your rhythm later.
Practical Tips
- Plan when you need light: go outside during the day, use bright light boxes, or try portable light-therapy devices.
- To avoid light that would shift your clock the wrong way, sleep or stay indoors, or wear sunglasses or glasses that block blue light in the range of about 460–480 nm.
- Drink plenty of water, avoid alcohol, and use caffeine cautiously—sometimes one cup at the right time helps; caffeine has a long half-life and can interfere with sleep.
- Start eating on the local schedule as soon as possible.
- Talk to your doctor about melatonin—it’s not right for everyone.
Can You Prevent Jet Lag?
Yes—if you shift your internal clock toward the destination time before you fly. “On average we can shift earlier by about 1.5 hours a day,” Burgess says.
To adapt to a time zone that’s 10 hours different, you would need to start changing your schedule at least a week before. One radical option is to flip your day and night—go to bed at 9:00 a.m. and wake at 4:00 p.m.—but that’s impractical for most people. When Burgess tried that schedule, she felt very isolated because everyone around her kept different hours.
If you can’t fully shift your schedule, start by moving your bedtime and wake time about 1 hour earlier each day for several days. Even a small move toward the local time before your flight can significantly reduce symptoms—especially when you’re flying east. “Spend five or ten minutes planning, and it will help a lot,” Burgess advises.
За матеріалами Live Science
Photo: Unsplash
