What is jet lag and how do you avoid its disruptive effects?

For many, one of the greatest joys in life is traveling and exploring new areas of the world. However, the adventurous joy comes with its downside. Jet lag affects us all on longer flights, as our internal clock gets out of sync. Jet lag is roughly similar to a hangover – yet, with the big difference that you probably didn’t have fun the night before.

While jet lag is annoying, keep in mind that it’s your body’s way of telling you that you’re far away from home and your rhythms are out of sync with local time.

But why does jet lag have such power over us, and is it possible to completely avoid its disruptive effects? In this article you will learn the answers to those questions.


All living beings are built to have a circadian rhythm, whether we talk humans, cats or even the plants of the earth. Circadian rhythm is an internal biological clock, so to speak, which affects when we sleep and everything related to the body’s rhythm, for example our temperature, hormone secretion, metabolism and digestion.

Many can recognize feeling more tired after the weekend. This is often due to a shifted circadian rhythm. We are driven by habits, and if we change them, our body is left confused.


Our biological circadian rhythm is controlled by a small collection of nerve cells called the suprachiasmatic nucleus. The nucleus lies in the part of the brain called the hypothalamus. It is located just behind the eyes, and thus, affected by light.

The human body is regulated by hormones. Each of the body’s hormones has its own cycle that interacts with and affects the other cycles. For example is the hormone melatonin high in the evening with darkness, while the hormone cortisol is high in the morning with sunlight. When either of these gets out of balance, our ability to sleep is affected.

The word circadian comes from the two Latin words, circa dies, which means “around the day”. Some studies have shown that our circadian rhythm lasts an average of 24.2 hours with individual variations (a single study with very few people measured 24.0-24.5 hours). Scientists don’t know exactly why, but the brain is built for a rhythm that extends beyond 24 hours.

However, if you stay for longer than a few days in a completely dark room, the internal clock will be disturbed. Your day will be pushed back and start later and later for each day.

There is a direct connection between the retina (where light hits the back of the eye) and the part of the brain that controls all these hormones. Body temperature, thyroid function, growth hormones, metabolic processes, adrenaline, and the sleep hormone melatonin are just some of the cycles that are affected by daylight.

With a lack of sunlight, your body does not produce enough of the signaling substances that make you happy, creative and awake. In other words, your hormone balance is out of balance without daylight. Artificial light has a certain effect, but daylight has a much stronger effect on the body.

Melatonin makes us sleepy

Our circadian rhythm is controlled not only by light, but also by the natural sleep hormone melatonin. Melatonin is produced in small parts in the brain called the pineal gland.

When it gets dark, the suprachiasmatic nucleus sends a nerve signal to the pineal gland, which then increases the production of melatonin.


Jet lag occurs when the brain cells that regulate our circadian rhythms are out of sync with the time zone we’re in. When there’s a mismatch between what your body thinks it should – like sleeping, for example – and what you want it to do, it can result in a number of physical ailments.

The main symptom of jet lag is altered sleep patterns, including insomnia during the night. Jet lag can also cause indigestion, reduced mental and physical performance, and reduced immune function.

Jet lag tends to get worse the more time zones you cross. According to a study conducted by researchers at the University of Maryland in 2016, symptoms are worst when traveling east, as our internal clock extends 24 hours in a day. As a result it is easier to extend the length of the day by flying west across time zones than to shorten it when flying east.

The symptoms of jet lag may feel like an annoying nuisance, but nevertheless the symptoms are real. Other studies have concluded that frequent air travelers may experience long-term health risks, including an increased risk of cardiovascular disease, cognitive impairment, and type II diabetes and, for women, disturbances in the menstrual cycle. Moreover, jet lag tends to get worse with age.


Since the circadian rhyme is crucial to our well-being, our internal clock will slowly reset so that it eventually corresponds to the new destination. This process can take a few days – not desirable on a holiday or business travel. There is no cure for jet lag, but there are tips you can follow before, during and after the flight to minimize the symptoms.


A few days before your flight, you should change your sleep rhythm so that it fits better with your travel destination. When traveling east, go to bed and set your alarm one hour earlier each day. The opposite is true when you travel west, where you have to move your sleeping routine an hour later each day. Also adjust meals and physical activities accordingly.

It is a good idea to add in a stopover if you have to cross more than five time zones. That way, your body can gradually adapt. Also, make sure you are well prepared for your trip and have all necessary travel documents. Stress and lack of sleep worsen jet lag. If necessary, you can check in from home.

It is crucial controlling your exposure to light, considering that your circadian rhythm adjusts to light. The blue light from your mobile and computer screen suppresses melatonin production and makes it difficult for you to fall asleep. In fact, the blue light from the electronic screens causes the body to produce up to 55 percent less melatonin.

Tip – specific food may promote better quality sleep or energy

Do you find it difficult falling asleep? Studies have shown that cherries and especially cherry juice of the Montmorency variety increases the body’s natural hormone melatonin.

According to a study from Louisiana State University, a glass in the morning and evening should provide up to an hour and a half longer sleep. At the same time, the tart cherry juice promotes the sleep quality. 240 ml of Montmorency cherry juice morning and evening should be enough. The extra melatonin can help your body fight jet lag and regulate the natural sleep cycle when you arrive in your new time zone

Other melatonin-rich foods that may promote better quality sleep or energy include healthy fat sources such as walnuts, pumpkin seeds, almonds, salmon and avocado, carbohydrates such as oatmeal, bananas, kiwi and brown rice, and protein such as soy, beans, eggs and turkey.


Set your watches to the new time zone as soon as you get on the plane and plan your activities accordingly. If it is night at your travel destination, it makes sense to sleep on the plane, even if you are not tired. Bring earplugs and a sleeping mask to block out noise and light. If you find yourself restless, it could help you doing a meditation or body scanning with deep breathing to achieve a calm and balanced state.

Avoid using your phone or watching movies, as the blue light, as written, disrupt the production of melatonin. Avoid sleeping pills. The very unusual environment on the plane already makes you sloppy. You risk feeling worse with sleeping pills.

Tip – lifestyle factors can impact our sleep and energy levels

Do you find it difficult to put your phone or computer away? You can enable night shift on your device. This changes the blue light to a warmer yellow color. If you want to avoid all blue light, you can get a pair of filter glasses with yellow glass. Studies have shown that you can advance the circadian rhythm and fall asleep more easily in the evening when you wear glasses that block blue light, a few hours before you go to sleep and for several days in a row.

Conversely, you must stay awake if it is daytime where you are going. In this case, you can choose an airline with a good entertainment program. The latest movies and TV shows are guaranteed to keep you awake!

Remember to drink a lot of water during the flight. The dry air in the plane strains our mucous membranes. The air sucks about 0.2 liters of water from your body per hour. This is roughly the equivalent of a 2L water bottle on a ten-hour long-haul flight. Jet lag worsens if you are dehydrated. Alcohol and caffeine-rich drinks are therefore a no-go, as it both affects your sleep negatively and makes you even more dehydrated.

You can advantageously skip meals on the plane. It will help you adjust to the new time zone faster as your body resets itself when fasting.

If you can’t stay away from food for that long, keep your meals light and balanced and synchronize them with the local time of your travel destination. A balanced meal is a meal rich in protein and healthy fats combined with complex carbohydrates such as sweet potatoes or quinoa. In this way, you will stay full for longer and at the same time reduce jet lag.


When you arrive at your destination, make sure you stay awake during daylight and only sleep when it gets dark.

One way to reduce symptoms and accommodate the new time zone is to get sunlight first thing in the morning. This helps reset the circadian rhythm. Try to get up before the morning sun if you have traveled east.

On the other hand, try to get the early evening light if you have traveled west. Fresh air will likewise prevent you from going to bed too early.

Stick to the local time zone and go to bed accordingly. If you still need a nap, don’t let it be longer than 20 minutes. If you sleep longer than 30 minutes, you end up in deep sleep. Hence, you will wake up drowsier. The ideal nap is between 10-20 minutes and gives you renewed energy.

Start eating your meals at the normal times for the local time zone, as this will help you reset your internal body clock.

You may want to do some exercise after arriving at your travel destination. It will make you feel more alert throughout the day and help you reset your body clock faster. In fact some studies suggest that a morning exercise can shift you circadian rhythm.

While exercise can help stabilize the circadian rhythm, it can also disrupt the body’s internal clock if you exercise too late in the day. The adrenaline rush you get from training makes it difficult for you to fall asleep. However, this only applies to intense exercise. Gentle exercises like yoga can actually improve sleep, when performed before bed.

Learn more about jet lag in this article and get 7 tips on how to avoid jet lag on your trip.

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