Irritability, grogginess, and constipation are just a few of the unpleasant side effects that many of us experience when traveling to a new time zone. If you love exploring the world but dread the first few days of waiting to feel human again, a study published September 5, 2023, in the journal Chaos offers a simple way to shave off a few days of jet lag: eat a solid breakfast for a few mornings in your new destination.
Jet Lag Isn’t Just About Daylight and Sleeping
Jet lag is caused by a difference between the circadian system (the body’s internal clock), and the surrounding environment. And although sunrise and sunset are part of that, researchers are discovering that there are other important cues that influence those cycles.
“Meal timing is important for circadian health, particularly as we now know almost every cell has a circadian clock which can be influenced by cues such as light or eating,” says a coauthor of the study, Yitong Huang, PhD, a postdoctoral fellow at Braun Lab at Northwestern University in Chicago. She says these findings, coupled with previous research, suggest that keeping those cues in sync is beneficial for our health.
Wait … Our Bodies Have More Than 1 Internal Clock?
The central circadian clock, called the suprachiasmatic nucleus, is located in the hypothalamus, deep within your brain, and basically synchronizes the body to the outside world, explains Jamie Zeitzer, PhD, a professor of psychiatry, behavioral sciences, and sleep medicine and the codirector of the center for sleep and circadian sciences at Stanford University in Palo Alto, California.
About 20 years ago, evidence emerged that the body has multiple internal clocks that are calibrated in different ways. “Nearly every cell and tissue in the body — for example, the liver, the kidney, the gut, heart, lung, and immune cells — they all have clocks,” says Dr. Zeitzer, who was not involved in the new research. The clocks sync up with the cells within their specific organ or function, and they also coordinate with other systems. So for example, liver cells are not only in sync with other liver cells, they also sync up with the clocks of kidney cells, and then they all synchronize through the central clock, he says.
Each relies on its own set of cues to calibrate, and while the brain’s clock depends on sunlight, the peripheral organs calibrate at mealtime, according to the authors.
“Conflicting signals — for example, eating when your brain is about to rest — can confuse internal clocks and cause desynchrony,” says Dr. Huang.
This isn’t just an issue for travelers; for shift workers, the condition can be chronic, and there’s evidence that sleep and circadian disruption increases with age, she adds.
Mathematical Model Mimics the Body’s Different Clocks
“The goal of this study was to use mathematical models to explore how to better improve circadian health given these types of disruptions. With this model, we can run computational ‘experiments’ to make predictions that can then be validated in animal or human studies,” says Huang.
The mathematical model was designed to mimic the natural rhythms of how the cycles oscillate and influence each other, and explore how external factors can disrupt those rhythms and lead to jet lag symptoms.
Scientists found that common symptoms of aging, such as weaker signals between circadian clocks and a lower sensitivity to light, result in a system that is more vulnerable to disruptions and slower to recover.
Using the model, investigators calculated that it would take an estimated five days for a person’s circadian clock to fully adjust to a six-hour time difference on a trip flying west and six days for eastbound travelers with a six-hour difference. For older adults, the model predicted it may take seven and nine days respectively.
The investigators tested four potential 24-hour meal schedules:
- Four equally spaced meals throughout the day and night
- Three meals when hungry
- Three equally spaced meals during the day
- Three days of eating a large breakfast and skipping a nighttime meal
After crunching the numbers, they found that, in addition to getting outside in the sunshine, three days of eating a large breakfast and skipping the nighttime meal was most beneficial, decreasing jet lag time by up to 44 percent. “Constantly shifting meal schedules or having a meal at night is discouraged, as it can lead to misalignment between internal clocks,” says Huang.
These findings basically align with the current thinking about circadian clocks, says Zeitzer. “By eating a large breakfast early in the morning, you’re helping to reset your gut clock. These peripheral oscillators (the circadian rhythms in the cells found through the body) can often shift faster than the central one in the brain, and that helps shorten the period when you might experience jet lag,” he says.
New Model Could Pave the Way for Personalized Medicine
“Our model is purely mathematical. While it can explain known physiology — such as the fact that jet lag from eastward travel is harder to recover from than westward travel — more studies are needed to fully understand how light and meal timing impact health,” says Huang.
But one of the great benefits of a mathematical model is that we can run “experiments” that would not be feasible to do in the real world, she says.
“Predictions from this model can be used to inform future studies and interventions that can be translated into practical use, such as an app that recommends optimal mealtimes. Because food schedules are often easier to adjust, we believe that this model paves the way for more personalized intervention strategies,” says Huang.
Zeitzer agrees, saying, “I think this work is important in that it extends beyond jet lag. We are really at the beginning of understanding how these various clocks work to synchronize health,” he says.
It’s very difficult, if not impossible, to record these clocks in humans, and so this kind of mathematical structure is critical in terms of generating testable hypotheses, says Zeitzer.
“This model — and the real-world tests that it could lead to — could play a large role in precision health, particularly in helping people stay healthy,” he says. Precision health is an approach that takes into account genetic makeup, family history, and lifestyle choices.
The authors plan to investigate the other side of the equation and identify the factors that result in more resilient internal clocks that eventually could be used to keep the circadian system healthy into old age.
Seasoned Travelers May Not Be Hit as Hard by Jet Lag
People who are routine travelers often aren’t as affected by jet lag because they’ve learned different tricks and remedies, says Zeitzer.
“For some people, it might be having an alcoholic beverage to help them fall asleep. Even though that’s not ideal, if it helps them sleep, I’m not opposed to that. For others, it might be yoga or a morning run. So when you travel, try to pay attention to what works and what doesn’t,” he says.
“Getting sunlight first thing is also great. Especially if you’re flying eastward, it’s a good thing to get that kind of big dose of sunlight that helps reset the circadian clock,” says Zeitzer. Even if it’s cloudy or overcast, you get way more helpful light going outside than you could ever get from indoor lighting, he adds.
Expert Advice on Minimizing Jet Lag: Don’t Try to ‘Tough It Out’
“Toughing it out is not a good plan — that sometimes makes it a lot worse. For example, I am not opposed to people taking pharmacological supplements [that have been prescribed or discussed with your doctor] to help them sleep on the plane or at the hotel after they arrive,” he says.
Melatonin is a reasonably effective sleep aid for jet lag, but you need to time it correctly, says Zeitzer. If you’ve flown east and want to reset your internal clock to an earlier schedule, then take the melatonin nightly, advises Mayo Clinic.
If you fly west and want to reset your body’s clock to a later schedule, take the melatonin in the morning until you adjust to the new time zone.
Finally, blocking out ambient light with blackout curtains or a sleeping mask can help you get a good night’s sleep, says Zeitzer.
