What ‘’jet lag’’ does to our bodies

As the holiday season across the Northern Hemisphere is in full swing, many holiday-goers who opted for a vacation requiring plane travel will have to pay an unpleasant price for this pleasure: jet lag. Being an often unavoidable side effect of long-haul travel, it has several effects on the human body that are often overlooked.

While the most obvious symptom of jet lag is fatigue, an article by the BBC breaks down what happens with our bodies when we embark on travels that involve crossing a significant distance over a short period of time.

This type of travelling has profound effects on the body, as it puts stress on our cells and organs, disrupts cell repair and alters liver and kidney function. A consequence could be headaches and sore muscles, while the disruption to our digestion can lead to nausea, diarrhoea or constipation. Brain fog is something often experienced by travellers when reaching their destination, which makes it hard to concentrate and affects memory. 

As the article explains, the main trigger for these nuisances is not a lack of sleep, but disruption to the body's biological clock. It runs on a cycle of approx. 24 hours, urging us to eat, sleep and be active at the right times.

Yet this schedule requires to be slightly reset every day because it is set to run at just over 24 hours. In order to keep the body working in sync, photosensitive retinal ganglion cells in the eye put a range of processes into motion when they detect darkness.

These result in the pineal gland – an organ the shape of a pine cone, which sits at the back of the brain – secreting the sleep hormone melatonin. The region of the brain responsible for these delicate tasks is called the suprachiasmatic nuclei or SCN and gets disrupted once we take a long-haul flight.

While unpleasant, most people are facing these side effects only on occasion unless their daily routine includes a substantial amount of long-distance travelling by plane. One such group includes the staff working on a flight, such as pilots and onboard personnel. According to the British outlet, their work schedules can make a significant difference to their body's ability to recover. 

One study compared female flight attendants working on schedules that include small breaks between flights, with flight attendants with more forgiving routines who crossed fewer time zones and travelled less frequently. The personnel in the group with the more demanding schedule were found to have higher levels of the stress hormone cortisol in their saliva.

While the body can cope with increased levels for short periods, long-term exposure to high levels of cortisol can suppress the immune system and raise the risk of cardiovascular disease.

Another study resulted in even more visible results, conducted at the University of California, Berkeley in the US on hamsters. The rodents were given a four-week sleep schedule, which was the equivalent of them flying from New York to Paris twice a week. When the hamsters were "jet-lagged", they struggled with tasks they usually found easy.

Yet the surprising finding was that even a month following the experiment, the animals still did not return to their previous state. After further research, the study found that the hamsters had stopped creating as many new brain cells as usual in the hippocampus while experiencing jet lag, a region of the brain associated with memory.

By Nazrin Sadigova