Jet Lag and Its Effects

Anyone who has travelled across multiple time zones will have experienced the unpleasant effects of jet lag, a condition also known as desynchronosis. Jet lag is a bone fide medical condition which results from changes in our environment, and more specifically, our exposure to sunlight, which in turn affects our biochemical clockwork. In this article we look what exactly jet lag is and what its effects can mean for you as a traveller.

The workings of jet lag

As a condition jet lag has derived its name from the fact that it is travellers aboard aircraft who suffer the effects of the condition. Only air travel allows us to cross time zones quickly enough to expose our bodies to the environmental changes that trigger the condition.


We are all sensitive to the day-night cycle which surrounds us, and our bodies are attuned to this pattern in such a way that most of us function at our best during the day and require rest in the evening. Key to this is a system of hormonal changes, referred to as the biological clock or circadian rhythm, which acts as a chemical trigger indicating to our body and its functions whether we should be awake or asleep.

As we are exposed to daylight, special receptors in our eyes detect sunlight and begin a cascade of signals that influence our wakefulness. While certain hormones peak during the day, stimulating wakefulness, others peak in the evening, signalling that we need sleep and rest. Melatonin is an excellent example of a classic circadian hormone, and the levels of this chemical peak at night to begin our sleep cycle. Because of this role, melatonin is often used as a drug to help travellers deal with jet lag, or even prevent it completely.

When we travel across time zones, particularly moving from the west to east where the sun rises, we are exposed to unusual amounts of light, and this will ultimately disrupt the sensitive system of hormones which control our wakefulness and our ability to sleep. The more our normal pattern is disrupted, the more severe the jet lag is, and the longer it takes to fully recover from the condition.

In short jet lag is a consequence of a disruption of our body clocks and hormone levels caused by travelling into a different time zone. In the following section of this article we will look at the effects jet lag has on our body.

Effects of jet lag

We experience jet lag as a series of different symptoms, and these will vary depending on how many time zones you have travelled across, the times of travel, and your body’s individual reaction to the changes experienced. A fit body in good physical condition will be able to better adjust to the transition, and will typically go through shorter jet lag.

Disturbances in sleep patterns are a classic effect of jet lag, and perhaps one of the most irksome of symptoms as most sufferers will also be quite tired. Typically this disturbance will present as difficulties in falling and staying asleep (particularly if flying in an eastward direction), and abnormally early awakening if you are flying west.

Jet lag will also have some cognitive effects which will include headaches, fatigue, and irritation, these will often be compounded by poor sleep. Many people with jet lag will also suffer some digestive effects, particularly in how often they will be able to defecate and the texture and consistency of their faecal matter. Many people enduring jet lag will find that they lose their appetite and ability to enjoy food.

These effects are all a consequence of the hormonal changes our body goes through when travelling across more than 3 time zones. Hormones are important chemical messengers with a number of far reaching effects on our body’s ability to function on a basic level, and many of the hormones involved in the circadian rhythm, like melatonin, have far reaching effects leading to the broad range of symptoms experienced during jet lag.

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