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Travel fatigue and jetlag - what's the difference?

Author Dr Ian Perry

Jetlag has a number of interpretations, mainly because we sometimes wrongly using the terminology to describe the fatigue that emanates from travel. The correct definition of jetlag is the uncurable biological function of trans meridian travel, where our bodies can’t catch up as quickly as the speed at which we’re travelling across multiple time zones. Neither supersonic jets nor Elon’s BFR (due to take us from London to Sydney in under an hour) will not reduce or reverse this biological process because the speed is irrelevant, it’s the number of time zones crossed that remains. 

When people complain of jetlag, they normal refer to feeling tired, lacking energy and struggling to sleep. These feelings can also be a result of the fatigue from travelling itself whereas jetlag is the altering of our circadian rhythms (our internal body clocks) to quickly adjust to the time zones crossed.

If I fly east from wherever I am, roughly every 1000 miles I cross a time zone, where I have to add on an hour to my home time. If I fly west, I have to take an hour off. 

Home time is where I spend most of my life, so that’s where my body clocks are all in sync, supposedly. Let’s say I go to bed around eleven, get up at seven, and eat two to three meals a day, usually at the same time most days. I empty my systems at usually the same time every day and live a regular working life. I’m considered a normal average person as my body clocks controlling my mood, sleep cycle, and all my other functions are together in harmony. This is called ‘Circadian Rhythm’. 

But this finely tuned balance can be disrupted without even going anywhere, as we lay in at the weekends, catching up on sleep we’ve missed during the week. This disrupts our regular daily bodily pattern and is commonly known as ‘social jetlag’. Or if you work a nightshift, or have just become a new parent, you’ll be exposed to the same effects of jetlag without having left the country.

Our bodies love a daily routine. 

But let’s say I need to travel for a business trip; I spoil my finely tuned biological balance and fly to New York or Hong Kong. Let’s go west to New York first. If I leave Heathrow at midday UK time, the flight takes for convenience 5 hours. I arrive in NY at midday, there is a 5-hour time change. My day is now 5 hours longer. Instead of going to bed at 23:00 hrs UK, I'm going to bed 5 hours later, that is 04:00 hrs UK time according to my body, which is now feeling very tired. 

I am meant to be asleep, but I am trying to stay awake and concentrate. This is something you should never do; you should never attend a meeting or be asked to make decisions this first extended day. All those synchronised body clocks have got to get adjusted to New York time. This is jetlag, everything is lagging behind and trying to catch up. If you are an airline pilot you may have to fly back after a few days, so your body has to readjust back to home time. If you are gone for two days, it will take two days to readjust.

Now if we go east, the same thing happens only the other way around. Hong Kong is about 6,000 miles from London, and it takes roughly 13 hours to get there. Most Aircraft fly at 500 mph so that is 12 hours flying (adding a bit for take-off and landing). The time in HK is 7 hours ahead of UK. If I leave London at 10:00hrs I should arrive at 22:00hrs UK time, just in time to go to bed, but sadly not as it’s 05:00 hrs in the morning in HK so just in time to get up. 

My advice to all who make such a journey is to do nothing this new day but get some sleep as it is now going to take you 7 days to readjust. Any company who sends representatives on such journeys expecting them to function properly immediately are severely mistaken. No one can make logical decisions when their brains are scrambled for a few days as their body clocks are out of sync. 

Brands and products who claim to cure jetlag should be taken lightly as the only way to prevent it is to never travel, sleep in or work a nightshift and to keep a tight daily schedule in terms of light exposure. Whilst nothing can cure the fact your body can’t biologically recalibrate with the number of time zones crossed quickly enough to not feel jetlagged, the body is fatigued as a result of the stress of travelling. From the journey itself and being dehydrated, overexposed to noise and stressed from other people’s schedules, and delayed flights, to the duration of the journey, this is what’s known as travel fatigue. 

Whilst we can’t ever biologically prevent our circadian rhythms becoming out of synchronisation whilst travelling, sleeping in or working night shifts, we can lessen the effect of the fatigue that arises from travelling by taking food supplements, exercising, hydrating and sensible eating to feel more energised during a trip.

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