Jet lag: The curse of the traveller

Travelling across different time zones can be both exhilarating and a curse. How do you stay awake during the day in Las Vegas when your body tells you it’s the middle of the night in London? Crossing multiple time zones can leave you exhausted and disorientated, all because your body is still synced to your original time zone. Is help at hand for frequent flyers?

You will eventually adjust to jet lag. However, it’s a slow process, and the recovery comes with a series of ailments including fatigue, lack of alertness, and even some digestive discomfort.

The fact is, the ability to jump multiple time zones is a recent achievement for humans and we’re yet to find a way to adapt. But what exactly happens in the body when we move quickly across time zones and is there a way to ease these effects?

Explaining jet lag

All life forms – including humans – have a circadian rhythm entrenched in the brain, capable of anticipating dawn and dusk. You can think about it like a ‘master clock’ that’s sensitive to light and which coordinates a set of other ‘clocks’ that regulate each organ.

Jet lag occurs when our internal clocks are out of sync with the time zone we are in. In other words, it sets in when you ask your body to be awake at a time when your internal clocks are desperately trying to tell you that it’s time to sleep. The problem is that each clock takes a slightly different amount of time to adjust to the new time zone, which is why we feel a little discombobulated.

It’s generally accepted that it takes one day to recover from jet lag for each time zone you cross. But in reality, jet-lag recovery doesn’t quite fit into this neat pattern. It mainly depends on which direction you’re travelling: it’s harder to recover when you fly east compared to when you fly west. This is easily explained with an internal clock that is naturally just over 24 hours, making it easier to make days longer by flying west than shorter by flying east.

It’s interesting to think why we need such a robust internal clock so resistant to changes. If you think about it, it makes sense to have a stable internal clock. Your body needs to be sure that the changes in light exposure are reliable and not just a one-off night with an exceptionally bright moon. If the signal repeats at the same time over a few days, then it’s more likely to be relevant. For frequent flyers, the problem is the same mechanism that ensures that we remain adjusted to our time zone is precisely what makes it so difficult to adapt to a new time. Hence, jet lag.

The feelings of being in the wrong time eventually disappear as the internal clock resets, but it’s a slow process.

It’s all about light

So, can we trick our biological clocks into not being jet-lagged? Is it possible to go on holiday and not feel miserable after the journey?

Sadly, the short answer is no. So far, there is no magic cure for jet lag. The feelings of being in the wrong time eventually disappear as the internal clock resets, but it’s a slow process. The best advice to recover from jet lag is exposure to light and dark at the right time. Light in the morning and darkness in the evening when travelling east – and the opposite when travelling west – are the best ways to realign your internal clock with the new time zone.

It’s easier to prepare in advance and move your clock before the flight rather than attempt to cure jet lag after arrival. Obviously, attempting to stay awake to mimic your new time zone before you travel will not solve anything. However, there may be a solution for this: studies show that short flashes of light during sleep may be enough to prevent jet lag. In effect, this is a way to trick the brain into adjusting to the new time zone by increasing light exposure without losing sleep. A kind of biological hacking, if you will.

This works because the cells in the eye that transmit to the brain continue to work for several minutes after receiving light. In other words, short flashes have the same effect as continuous light. For example, if you’re flying from London to Abu Dhabi, you need to use light therapy for three hours before your usual wake up time. When you arrive, your body is already in the process of moving to the new time.

The sleep hormone

The second factor that has been extensively studied in this field is a naturally occurring hormone called melatonin. Often referred to as sleep hormone, the production of melatonin increases with evening darkness and promotes healthy sleep patterns.

Synthetic melatonin is often prescribed to treat sleep disorders, and there is some evidence – albeit limited – that it can help with jet lag. However, it is crucial that it is taken at the right time, or it may make adaptation worse. When going east, melatonin should be taken in the afternoon, whereas when going west, it should be taken in the morning. The idea is to mimic the natural melatonin production for the new time zone. However, there are some concerns about this approach to treating jet lag. For some researchers, there just isn’t enough evidence that prescription melatonin makes a major difference to relieve symptoms.

For the sweet tooth

Finally, researchers are working on a possible treatment that will appeal to those with a sweet tooth. It turns out that chocolate for breakfast may just be the key to synchronise to a new time zone. There isn’t anything particularly special about chocolate, and other foods with an equal amount of sugar and caffeine are likely to work just as well. It’s important to note that these studies have only been done with rats, and further work with humans is needed. Also, rats needed to eat a substantial amount of chocolate to see any effects. For humans, this would be the equivalent of eating three or four large chocolate bars for breakfast. Is avoiding jet lag really worth the stomach ache?

Alex Reis is a freelance science writer based in the UK

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