The Science of Jet Lag


It’s only been in the last few decades that long distance travel has become commonplace in our lives. With it has come the phenomenon of desynchronosis, a combination of symptoms including headaches, fatigue, and loss of concentration. This is better known as Jet Lag. Resulting from the disruption of our bodies circadian rhythms –  the collection of processes that ensure that all our body functions follow a roughly 24-hour clock, Jet Lag can make travelling on holiday or to a business meeting on the other side of the world a nightmare for even the most seasoned traveler. But what exactly is it about travelling across multiple time zones that so badly disrupts our systems, and are there ways to minimise its impact?

What is Jet Lag?

Our bodies internal clocks are regulated by a hormone,melatonin, in an area of the brain called the pineal gland. As night time approaches, the pineal gland produces more melatonin, which has lots of effects on our body – the most obvious being that we become tired, triggering us to sleep. This system relies on us being exposed to different light levels during the day – as light levels begin to fall in the early evening, different genes are switched on or off, getting us ready for sleep. This is all overseen by an area of the brain called the hypothalamus, which scientists refer to as the ‘master clock.’

Travelling across multiple time zones completely messes up the regular system going on in our brains by either extending or reducing the amount of time we are exposed to daylight. As an example, a Flight from London to New York can take around eight hours. Because you are flying ‘backwards’ against time zones, you’ll arrive in the United States only three or four hours later than you left London, effectively creating a time ‘lag’ of over four hours.

For longer flights, these delays become even more significant, but it is ‘forward’ travel that has the greatest impact. As you travel eastward, you are shortening your day, resulting in your brain having to process the idea that it must sleep much sooner than it would normally have to. This results in a lot of internal ‘confusion’ – processes regulating everything from sleeping patterns to digestion are thrown out of kilter, resulting in the typical symptoms we associate with Jet Lag.

How might we minimise its effects?

Research carried out by a group of scientists at the Nuffield Laboratory in Oxford in mice has shown that a protein, SIK1 plays a role as a kind of natural brake mechanism in the mouse, responding to light exposure and stopping the mouse’s body clock. By inactivating this protein, the scientists could produce mice which can adjust to changes in time zones much quicker. Work done by these scientists, as well as research carried out in Japan, has opened the door to the idea of a jet lag ‘cure’ – a medication able to block a similar protein found in humans. However, with much of their work in the experimental stage, the idea of a wonder cure to jet lag is some way off.

Is it possible that there might be other, more easily adopted ways to minimise the effects of Jet Lag? One way might be to take melatonin orally in small quantities – work at Rush University Chicago has been exploring the impact of giving small doses (0.5milligrams) along with exposure to ‘light boxes.’ They’ve demonstrated remarkable results, resetting subject’s circadian rhythms and minimising the impact of Jet Lag. Since then, there’s been an explosion in mobile apps and programmes such as Entrain, designed to help travelers adjust to crossing time zones by telling them when to expose themselves to bright light. Many of these programs have had limited testing, so it’s good to be wary of so called ‘miracle cures.’

In retrospect,  Jet Lag is unavoidable, with the advent of long distance travel in the last few decades meaning we’ve had little time to evolve to the challenge, and whilst we might try to avoid light exposure at certain times and try to maintain a normal sleep cycle, overcoming our own natural body clocks is a pretty big ask all the same.

#Health #JonathanJames

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