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Jet Lag (Desynchronosis) – Definitive Guide for Smooth Time Shifting

For most people, Jet Lag (often described as a bad case of hangover, without the great night out) is no more than minor annoyance. First of all: it only affects those who travel by plane (which literally translates to millions of people every year though), and among those, only travelers who move East-to-West, or West-to-East. Those who travel along the North-South axis, will largely remain within the same time zone, so for them, Jet Lag isn’t even a minor nuisance.

Let us face it though: most intercontinental travel happens in an East-West/West-East direction, and thus jet lag is a problem for many, especially for people who travel a lot.

What exactly is jet lag though? 

Jet lag is a (rather unpleasant and potentially intrusive) condition, triggered by the difference between actual, environmental time, and one’s internal, biological clock. The difference is due to rapid travel eastward or westward, of the kind made possible by jet airplanes, which takes the traveler across several time-zones.

Circadian biologists will be the first to point out why this internal biological clock is so important, and anyone suffering the ill effects of jet lag will be quick to concur.

The severity of jet lag depends on a number of factors, such as the length of the journey and the number of time-zones through which it leads.

The direction of the travel is also important: East-to-West travel is less intrusive in this regard than West-to-East travel.

Other important factors are the ability of the traveler to catch some shut-eye during travel and the exposure of the subject to local circadian time cues once the destination is reached.

What is a time zone?

A time zone is a geographical area about 1,000 miles wide (from East-to-West), within which, the time is the same. There are exactly 24 such strips, covering the entirety of the globe. The time-difference between the 1st such strip and the last one is always 24 hours – meaning that each time-zone covers one hour of the day.

The width of the time zone is not rigid: it follows geographical and political borders, where such a need arises.

In the US alone, there are 4 time zones: the Eastern Time Zone is the Easternmost, followed by the Central Time Zone, the Mountain Time Zone and the Pacific Time Zone. The sun rises a full 4 hours earlier in the Eastern Time Zone, than it does in the Pacific one. Thus, it is possible for people flying across the US to experience some degree of jet lag as a result.

How does your body tell time?

I mentioned your internal, biological clock above. How exactly does it work? The body observes a 24h circadian cycle, which is in effect controlled by the hypothalamus. In turn, the hypothalamus takes its cues from the optic nerve, which tells it when it is night and when it is day.

Based on these cues, the hypothalamus regulates a number of physiological functions, such as hunger, hormonal levels, blood sugar levels, blood pressure and even body temperature. When it’s time to sleep and to wake up is also subject to the hypothalamus’ regulatory activity.

When the actual time of day no longer corresponds to the biological clock of the body, the hypothalamus hands out “commands” that might tell you to go to sleep in the middle of the day, or to become hungry in the middle of the night.

Obviously, despite this confusion, if the right cues are given to the hypothalamus by the optical nerve, it is bound to straighten out much more quickly than it would otherwise. This further underscores the importance of circadian adaptation through proper light exposure.

Long story short: you, the jet lag-sufferer, can in fact tweak your internal clock, by exposing yourself to light during the daytime of your destination time zone, and depriving yourself of light during the nighttime of that same time zone.

In fact – as I’ll detail below – you can perform such adaptive measure preemptively, before your journey commences.

What are the symptoms of jet lag?

While most of the symptoms of this potentially disruptive condition are quite common-sense and straightforward, there are some entirely unexpected ones too.

Obviously, the most common symptom of jet lag is daytime drowsiness and the inability to get quality (or any) sleep at night. This is all due to the fact that the subject’s biological clock is set to put the subject to sleep when he should be awake according to the environmental time of his new location, and to keep him awake when he should be asleep.

Jet Lag

Less common symptoms include gastrointestinal issues in the new time-zone, where the subject’s body is fed at times entirely unexpected by his biological clock.

While jet lag-induced problems can be surprisingly annoying and even rather dangerous/counterproductive for those who have to perform some sort of physical/mental task (like driving or playing in a sports game) in their new time-zone, the good news is that its symptoms subside relatively quickly – meaning a few days, although sometimes, the symptoms may prove more stubborn.

In rare cases, the symptoms can turn into serious ones. Some people experience an increased proneness to illness while others may develop heartbeat irregularities. If such symptoms are indeed experienced, and they persist, the assistance of a doctor should be sought.

Those with preexisting heart conditions should be extra careful in this regard. In the elderly, the symptoms of jet lag may be more intense and they may last longer.

It is estimated that for every time-zone crossed, complete circadian adaptation may take as much as a full day.

There are a number of measures one can take to hasten the subsiding of these symptoms though.

Dealing with jet lag

To successfully tackle the problem, one needs to understand its peculiarities, as well as his/her own circadian clock. The circadian cycles of most people are longer than 24 hours. For a minority of about 20% though, this does not hold true. The circadian cycles of these people are shorter than 24 hours. Such people will find it much easier to handle jet lag induced by eastward travel.

Exposing the body to environmental cues (light during the daytime) in the new time-zone, is a rather self-explanatory approach, though there are quite a few other things one can do to lessen the impact of jet lag, before and during travel.

Eastward travel

Promoting sleep during Eastward travel is one such measure. There’s a reason why most flights from the US to Europe are scheduled for the night. Those who manage to sleep through such a journey, will awaken in Europe in the morning, thus they’ll slip into their new environment’s day/night alternation quite seamlessly.

There are scores of ways to promote sleep during flight, some more helpful and less intrusive than others. Using noise-cancelling headphones, eye shades or special sleep masks is a good idea. As much as you are tempted to consume alcohol to promote sleep, you should steer clear of this path: alcohol will disrupt sleep continuity and adversely affect sleep quality.

Some take melatonin supplements before taking off, but that – as some experts are quick to point out – may not be such a wholesome approach either.

Westward travel

As said above, westward travel-induced jet lag is somewhat easier to handle, on account of the fact that most people’s circadian cycles are longer than 24 hours. What that means is that most people will find it relatively easy to stay up past their usual bedtime, and that is exactly what is required of them, to alleviate the impact of jet lag in this case.

Of course, there are other ways to keep awake during the flight from Europe to the US for instance. Caffeine comes to mind first, but obviously, there are pharmaceutical solutions too, like Modafinil. One should always exercise caution with such compounds though: they tend to come with some rather scary side-effects.

Circadian adaptation is one of the best ways to address the issue of jet lag. It is non-intrusive in the sense that it does not require the ingestion of potentially dangerous chemicals and it is indeed a proven way to handle the problem. Furthermore: it can be used before, during and after travel as well.

After-travel use of circadian adaptation is the most straightforward approach in this regard, though pre-flight partial adaptation can contribute to the shortening of one’s jet-lag affected time as well.

The pre-adaptation routine is meant to serve the delaying of one’s bedtime in westward travel and the bringing forward of one’s bedtime in eastward travel.

As such, if you are set to travel from the US to Europe, try to get up as early as possible and go to bed as early as possible too. Stick to this routine for 1-2 days at least, for the best results.

If you’re scheduled to fly from Europe to the US though, try to sleep in, and then go to bed as late as possible.


The role of light can never be underestimated in anything linked to the circadian clock. It does indeed play a major part in the above described pre-adaptation routine too, as well as in post-travel circadian adaptation.

In the above example, as part of the routine preceding an eastward flight, one should accompany the early awakening with exposure to bright light. The early bedtime can be complemented with dim lighting.

For westward travel, the late awakening should be accompanied by dim lighting, while the late bedtime should be paired with exposure to bright light.

There are different ways to use light to induce these desired effects, but the best (and simplest) way is still to simply turn a lamp on or off.


As mentioned above, melatonin can be used as a sleep-promoting supplement. Melatonin is in essence a hormone produced by the brain in response to darkness. Also called the “darkness hormone”, its role is to usher in sleep. In this regard it is a viable solution for in-flight sleep promotion- at least in theory.

Doctors have cautioned though that despite its seemingly harmless nature, melatonin may produce some significant side- effects, one of which concern the functioning of the reproductive organs. In addition to that, the unregulated supplement industry cannot be relied on for the quality and indeed: dosage, delivered through these rather dubious products.

As far as natural melatonin sources are concerned, you should know that 2 pistachio nuts deliver a dose of melatonin which should in theory easily cover your sleep-promoting needs.

Other jet lag-fighting solutions

Whenever there’s a problem, there are always people willing to come up with some type of solution for it, either in the shape of an app, or some kind product for which money can be charged.

Jet Lag Rooster (jetlagrooster.comis a browser-based app, which draws up an easy-to-understand pre-flight, during-flight and post-flight circadian adaptation schedule for those too lazy to do the “math” themselves. It does it all for free too.

The app requires users to enter a number of variables regarding their travel plans, such as their point of departure and destination, the times involved and their usual bedtime/awakening time. Users can choose whether they want the pre-, during, or after-travel stages of the adaptation routine drawn up.

The app then tells them when to go to bed, when to awaken and when to use increased exposure to light, for up to10 days before their flight.

While the homepage of Jet Lag Rooster claims the app has been featured on a number of top news outlets, such as CNN and BBC, we found no trace of it anywhere on those websites.

Timeshifter (timeshifter.comalso claims such dubious laurels, and it allegedly delivers “personalized” schedules to combat jetlag.

In the shape of a mobile app (available for Android, as well as iOS-based devices), Timeshifter schedules various small actions (like avoiding coffee and seeing a bright light) throughout the day, and it delivers them through a graphical user interface, and even in the shape of alerts, in real time.

By following the advice/schedule delivered this way, the user will significantly alleviate his/her jet lag-related problems.

The Timeshift website lists an impressive number of scientists and researchers who have apparently contributed to the app.

Does it work? Based on the above said, it probably works well indeed, as it makes use of well-known and tested circadian adjustment methods.

Conclusion – How to prevent/overcome jet lag?

Taking all the above into account, the bottom line is that physical circadian adaptation is the best way to handle – and perhaps to prevent to some degree – the ill-effects of jet lag. After all, the condition results from the unnatural mixing up of one’s circadian cycle. It makes perfect sense to tackle it “at the source”.

I also have to point it out that thus far, the FDA has not approved any drugs/medication for the treatment of jet lag.

That said, it makes sense to sum up the measures you can take to tide yourself through the ill effects of jet lag more quickly and easily.

  • if you have a preexisting medical condition (including but not limited to heart disease and diabetes) ask for medical advice before you travel.
  • begin adjusting your internal clock to the time zone of your destination some days before your travel commences – as I detailed it above for Eastward and Westward travel.
  • steer well clear of alcohol. It can have a series of adverse effects on your body (no surprises there, really), such as provoking dehydration and messing up your sleep schedule (which is truly the very last thing you need).
  • for the same reasons, avoid caffeine as well.
  • while you definitely won’t be able to accomplish this within mere days of your departure: it is always a good idea to be generally fit and in shape. A strong and healthy body will deal much easier with whatever jet lag throws at it.
  • breaking up your trip into several shorter legs if possible is also a good idea. I do fully understand though that most people won’t be able to afford this sort of luxury.
  • stay well hydrated. Dehydration is one of the alleged side-effects of long airline travel and it makes the symptoms of jet lag much worse too.
  • make sure you get up and move around in the plane as much as you can. Doing this, you shall ward off stiffness and you’ll stay mentally alert. You will also prevent the formation of blood-clots in your legs – something that can indeed happen when you’re sitting in one place for hours on end.
  • for the same reasons, wearing loose-fitting clothes and shoes while traveling is a good idea as well.
  • as soon as you arrive, make a conscious effort to adapt to the local day/night alternation as soon as possible.
  • make sure that your hotel room allows you to do just that. If it is unsuitable for whatever reason (too dark, too hot etc) ask for a different one.
  • try not to use sleeping pills during your accommodation-phase. if your doctor prescribes such pills to you though, stick to the prescription.

If you do have to resort to pills, here are a few OTC and prescription solutions that you will likely take (I have to reiterate that none of these solutions are FDA-approved).

As far as the OTC side of the equation is concerned, I have to point out diphenhydramine (which you will likely take as Sominex or Nytol), as well as doxylamine (Unisom).

Prescription drugs may run a much wider range: from melatonin receptor agonists such as Rozerem, to quick-acting sedatives such as Lunesta, Ambien and Sonata, all the way to tranquilizers such as Restoril and Dalmane, everything is “fair game” here.

Again: be mindful of the fact that the side-effects of such drugs my far outweigh their benefits in relation to jet lag.

The risk factors associated with jet lag are:

  • age (the older you are, the more severe your symptoms are likely to be).
  • traveling across more than 3 time zones.
  • traveling Eastward
  • traveling while under the influence (even if just a little).
  • being a frequent flier (people whose jobs involve frequent travel are especially vulnerable).
  • traveling with a preexisting medical condition.
  • less than ideal flight conditions.