Appliance of Science: What is jet lag and can you avoid it when travelling long-distance?

It is the travel season again and many are heading off on holidays. For some, that trip takes them to far flung places and they may experience the downside to travelling across different time zones – the dreaded jet lag. But what exactly is it, can it be avoided or is it destined to knock you off kilter and rob you of a few days of that precious holiday? asks Dr Naomi Lavelle

Appliance of Science: What is jet lag and can you avoid it when travelling long-distance?


Jet lag is a relatively new condition; the term was only coined in the 1960’s when air travel became more popular and jet planes allowed people travel at speeds never before imagined. The technology meant they could travel across time lines within hours, however their bodies took a bit longer to catch up and the term Jet Lag was created to describe the symptoms they felt as a consequence of this jet set lifestyle.


The medical name for jet lag is desynchronosis and it is a change in our bodies’ internal clocks (our circadian rhythms) caused by air travel across different time zones.

The more time zones we travel, the more our bodies’ internal clocks get knocked out of sync. It takes longer to recover when travelling from West to East as we lose time as we travel.

The symptoms of jet lag include disruptions to sleeping and eating patterns as well as possible changes to blood pressure and body temperature.


We have a number of finely tuned internal clock systems that keep our bodies regulated. These clocks are set to a day that is approximately 24 hours in length. Travelling to a new time zone upsets these systems and it takes them a while to recalibrate.

The master clock of the body is the superchiasmatic nuclei (SNC) within the hypothalamus of the brain. It controls the hormones, the clock genes and the neurons that control the daily rhythms of our bodies. The pineal gland near the centre of the brain produces a hormone called melatonin that controls our internal clocks. It is usually produced as it gets dark, triggering tiredness. When we change time zones the production of melatonin is disrupted and our sleep patterns and body temperature control mechanisms are modified.

Light can also alter the expression of certain clock genes within the SCN. These changes disrupt the body’s 24 hour system and it takes time to readjust; we can usually only reset the clock at a rate of one hour per day.


Unfortunately our bodies are not designed to travel across time zones at such speeds and there is no avoiding some of the symptoms but there are things we can do to reduce the effects and increase our recovery time.

The sooner we can reset our internal clocks to the new time zone, the more quickly we can recover and enjoy our holiday. One way to do this is to start to adjust our daily routines before we even take the trip.

Altering our bed times and exposure to daylight to better align with the new time zone can mean we are well on our way to recovery before we even get on the plane.

It also helps to stay hydrated while travelling and to get as much exercise as possible.

Naomi is a science communicator and mother to three inquisitive children. She can be found at sciencewows .ie

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