Why am I having jet lag?

Jet lag occurs because your internal body's clock, also called the circadian rhythm, is still synced to your original time zone, instead of the new time zone at your arrival destination.

The circadian rhythm is a roughly 24-hour physiological cycle happening in your body every day. There are clear patterns of brain wave activity, hormone production, cell regeneration and other biological activities linked to this daily cycle.

When you travel across time zones this natural daily cycle is interrupted and you experience jet lag. The more time zones crossed, the longer the jet lag will last.

Your internal body clock will in general use one day per timezone offset to fully adjust to the new destination time. For example, if you crossed six time zones, the body will typically adjust to this time change in four to six days.

Is this you?

Your alarm clock sets off. You blink one eye open and reach for your phone. 08.30 am. You hit the snooze button and fall fast asleep again. You’re woken up the second time by sunlight hitting your face through the curtains. You are suddenly wide awake and grab your phone on the nightstand.

1.30 PM - You have overslept to your breakfast date with a friend you’re visiting in London. Back home in Los Angeles, the day has just started. You feel irritated, sleepy and completely out of sync. You are experiencing jet lag!

Jet lag can be described as a conflict between your internal clock and the external stimuli, also called “zeitgebers”.

External time-givers, are all the signs in your environment which tell you what time of day it is. Light is the most important zeitgeber for human beings because exposure to sunlight each day helps reset the internal biological clock to the 24-hour cycle of the earth’s rotation.

If you have crossed time zones in your travels, you know how out of it you might feel trying to adjust to your new environment. Most people will experience fatigue, irritability, sleepiness, headaches but also problems with digestion and reduced interest in food.

Studies have shown that experiencing jet lag over a long period of time can contribute to generally poorer performance on mental tasks and concentration. One study showed that flight attendants who crossed time zones at least once a week for four or more years had reduced reaction times and 9% more mistakes on memory tasks than local crews who did not cross time zones.

Why do these symptoms occur?

When you’re traveling across a number of time zones, the internal body clock will be out of synchronization with the destination time, as you experience daylight and darkness contrary to the rhythms to which you’re used to.

The rhythms that dictate times for eating, sleeping, hormone regulation, and body temperature will also no longer correspond to the environment. That is why you might lay awake at 3 am, tossing and turning or sleep later than you normally do when you’re home. You might get hungry at odd hours or don’t get hungry at all.

The travel in itself can’t be blamed for giving you jet lag. Jet lag is actually only linked to west or eastward travels! A ten-hour flight between Europe and southern Africa does not cause jet lag, as the direction of travel is primarily north-south.

Los Angeles to London.

On the contrary, a ten-hour flight between Los Angeles and London will result in jet lag, as the direction of travel is primarily west-east. 

It has also been showed that jet lag is worse when traveling eastward. For example, a Londoner traveling to Los Angeles will go to bed eight hours later than they’re used to but then has the opportunity to sleep later. Most of us will not find that too difficult.

In contrast, an LA traveler to London will have to go to bed eight hours earlier than they’re used to and awaken in what feels like the middle of the night. In theory, it will take you eight days to fully adjust to the new time in London.

So if you are traveling from Los Angeles to London for a weekend. Your body will experience the symptoms of jet lag the whole stay. 

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