Let’s be clear: Jet lag is more than a sleep problem. That’s why its symptoms don’t just disappear after a good night’s sleep. Jet lag is when your body optimizes all your daily functions (your circadian rhythm) based on a “wrong” time that it thinks it still is. It just doesn’t know the new local time yet.

How can you use your circadian rhythm to beat jet lag? You can beat jet lag when you align your circadian rhythms to your new time zone. And for this, you need to use the right environmental cues at the right time: your daily light exposure, your eating timings, and when you exercise.

How to beat jet lag if you fly east	How to beat jet lag if you fly west
Light: Maximize your (natural) light exposure in the first part of the day and minimize your (artificial) light exposure in the evening and at night. Food: Stop eating a little earlier than normal before your travels. Then only eat during local eating times. Don’t eat at night. Exercise: Exercise in the morning or late afternoon/ early evening.	Light: Reduce your (natural) light exposure in the first part of the day and increase your (artificial) light exposure in the evening (not at night). Continue only until you’ve adapted. Food: Start eating a little later than normal before your travels. Then only eat during local eating times. Don’t eat too early in the morning. Exercise: Exercise in the evening.

Read on to get a full understanding of:

• What the connection between your circadian rhythm and jet lag is
• Why you experience jet lag because of the misalignment between your circadian rhythm(s) and your new local time
• What symptoms of jet lag you experience and how they are all connected to your circadian rhythm(s)
• Why the key to beat jet lag is to align your circadian rhythm(s) to your new local time
• How you can align your circadian rhythm(s) to your new local time through leveraging their environmental cues (zeitgebers)
• What additional hacks you can use to minimize jet lag
• How you can implement all scientifically proven ways to beat jet lag (with details for both flying east and west)
• How long it normally takes for your circadian rhythm to adapt to a new local time zone
• Which additional factors impact how successful you beat jet lag
• My personal experiences and your key takeaways

Are you only interested in beating jet lag without getting the full story behind it? Sure, I’ve got you covered! Use the links below to directly jump to the practical tips on how you can beat jet lag:

#1: Jump to how you can align your central (master) circadian rhythm to your new local time zone through your light exposure

#2: Jump to you can align the circadian rhythm of your organs to your new local time zone through your eating timings

#3: Jump to how you can align the circadian rhythm of your muscles and tissues to your new local time zone through exercise and activity

#All: Jump to how you can implement all scientifically proven ways to beat jet lag (with details for both flying east and west)

Now, without further ado, let’s start with the connection between your circadian rhythm and jet lag. Or better, why you experience jet lag because of your circadian rhythm.

Circadian Rhythm and Jet Lag

What Is the Connection Between Your Circadian Rhythm and Jet Lag

To help you beat jet lag, it is important to understand what causes it. And this starts with your circadian rhythm. Or better the misalignment of your circadian rhythm after you’ve crossed several time zones.

Let me explain: Your body has to perform many functions every single day (most notably your sleep-wake-cycle). But it can’t perform all at once. So, what does it do instead? It optimizes the timing of all your functions over every single day. This is called your circadian rhythm.

And your circadian rhythm – that optimizes all your body functions – works based on its own internal time. This is roughly twenty-four-hours long (ok, for most people slightly longer) and needs to be aligned by environmental cues (called zeitgeber) to you external, local time.

Now, what happens if you fly across time zones into a new external (local) time? Well, while your watch can tell you the difference, your internal time hasn’t changed that quickly. It needs to be realigned first with its zeitgebers (those environmental cues).

But your circadian rhythm always and only optimizes your daily functions based on your internal time.

And this is exactly why you experience jet lag. You have just arrived in a new time zone, but your body doesn’t know that yet. Your internal time is different from your external time. That means that your body can’t optimize your functions (including your sleep-wake-cycle) based on the new time zone. Because it doesn’t know yet about this new time zone.

You experience jet lag because of two problems:^​1,2​

1. Your central (master) circadian rhythm is not aligned with your external time.
2. Your three core circadian rhythms are not in harmony.

How do you align your internal time to your external time again? Through the help of those external stimuli – called zeitgeber – that align your internal clocks.

If you want to find out everything about zeitgebers, you can check them out in this post here: “What are Zeitgebers and Which Are the Most Important Ones for You”

Sneak peek: If you want to beat jet lag then you need to use your zeitgebers – that align your internal clocks to your (new) external time. And I’ll show you how to use them strategically for your next travels.

But first things first, let’s have a look at what happens inside your body when you experience jet lag.

Misalignment Part I

Misalignment Between Your Central (Master) Circadian Rhythm and Your External Time

One of the biggest problems with jet lag is that you can’t sleep properly during the night. Even though you have been quite tired all day long.

You want to know why? Because the circadian rhythms of the three key factors for your sleep are messed up. And that causes a big part of your jet lag. Here are these three key factors for your sleep:

1. The circadian rhythm of your core temperature. Yes, also your core temperature has a daily rhythm. And it is optimized for your activity levels. In short, your core temperature is highest in the afternoon, which allows you to reach your physical peak performance at your lowest injury risk. And it is lowest at night, which allows you to sleep best.^​3​
2. The circadian rhythm of melatonin. Melatonin helps your body to wind down and to prepare you to sleep. It makes you feel sleepy and is vital for good sleep quality. Your body normally starts producing melatonin in the evening and stops its production in the morning.^​4​
3. The circadian rhythm of cortisol. Cortisol helps your body to feel energized. Your body normally starts producing cortisol in the morning and stops its production in the evening. It also has a bad rep as your stress hormone. But don’t let that fool you.^​5​

And what do all of these three factors have in common? They are under the control of your central (master) circadian rhythm. That follows your central body clock.

Here is what leading researchers Jim Waterhouse and colleagues, from the Liverpool University, wrote about jet lag in their paper called “Jet lag: trends and coping strategies:”^​2​

“Jet lag is caused mainly by inappropriate timing of the body clock in the new time zone.”

Jim Waterhouse et al.

Now, when your body clock tells your central circadian rhythm that it is day, you have a hard time sleeping. No matter if it is already late at night. Your core body temperature is too high, your melatonin levels too low, and your cortisol levels too high.

And when your body clock tells your circadian rhythm that it is night, you feel sleepy instead of energized for the day. No matter if it is daytime. Your core body temperature is too low, your melatonin levels are too high, and your cortisol levels are too high.

Unfortunately, that’s also the case for the majority of us who live against their circadian rhythm. At least to some extent. If you generally have a hard time waking up (feeling too sleepy) and falling asleep (still feeling too energized), I recommend you to check out this post: “Get Your Circadian Rhythm Back on Track: The Ultimate Guide”

Misalignment Part II

Misalignment Among Your Three Core Circadian Rhythms

Ok, the misalignment of your central circadian rhythm – as in the example above – is just one part of the story. Even though it is the biggest reason for your jet lag.

But you actually have two more core circadian rhythms. What? There’s more than one circadian rhythm? Yes, you have three core circadian rhythms! But let’s be very clear, your central (master) circadian rhythm is by far the strongest and most important one. And it orchestrates your other rhythms – which is just fancy speech to say that your central circadian rhythm makes sure that they all have the same internal time.^​6​

Actually, there are even more circadian rhythms that your central (master) circadian rhythm orchestrates. And even virtually every single has its own one. But normally you wouldn’t know because they are all aligned. Check out this post “How Many Circadian Rhythms Do We Have” if you want to find out more.

And each of your three core circadian rhythms has their own zeitgebers that align them to your external day. And that is before your central (master) circadian rhythm can orchestrate.

Core circadian rhythm	Zeitgeber (environmental cue)
Central (master) circadian rhythm	Light exposure
Circadian rhythm of your organs	Eating timings
Circadian rhythm of your muscles and tissues	Exercise and activity

Now, here’s another reason why you feel off when you experience jet lag: Your three core circadian rhythms align at a different pace to your new time zone. This means that they have different internal times for a while. And the body functions that they each optimize are not in harmony among your circadian rhythms.

Now, what does that mean for you? 

1. Each core circadian rhythm controls different body functions. And each circadian rhythm also presents you with a different set of jet lag symptoms. 
2. You can help your core circadian rhythms to adapt quicker to a new time zone with the help of their zeitgebers (your environmental cues). 
3. This minimizes the specific symptoms of jet lag for each of your core circadian rhythms.
4. But it leaves your three core circadian rhythms in disharmony for a bit.

So, what do you want to do? You want to help your three core circadian rhythms to align with your new local time as fast as possible. For this, you need to maximize the impact of their zeitgebers. And this minimizes the symptoms of jet lag for each of your core circadian rhythms.

Speaking about jet lag symptoms… Let’s have a quick look at these now. And then we’ll dive deep into how you can beat jet lag.

Jet Lag Symptoms

The Jet Lag Symptoms You Experience

Now, let’s be clear first about what the symptoms of jet lag are. They are those that you experience when you cross time zones. And your internal time (that controls your circadian rhythms) is different from your new external time.

This is important to remember because there seems to be some confusion about jet lag and travel fatigue. In short, travel fatigue comes from any journey that is long enough. Regardless of whether you travel across time zones (west or east) or not (north or south). Dehydration, lack of movement, a pressurized cabin, and also loss of sleep on the day of travel typically cause travel fatigue. But those symptoms are usually gone the next day.^​1​

Jet lag, as you have seen, is a misalignment between your internal time(s) and your new external time. And while tips like drinking a lot of water, moving regularly or sleeping or not do help you to combat travel fatigue, they don’t help you to beat jet lag.^​1,2​

So, let’s get back to the symptoms of jet lag again.

The most intense symptoms of jet lag are those that you experience because your central (master) circadian rhythm is not aligned with your new external time:^{​1,2,7,8​}

• You have issues sleeping and are tired during the day. It is especially difficult for you to fall asleep and wake up early if you fly east and stay up late and sleep long enough if you fly west.
• Your mental performance is worse. Especially your alertness, your attention, and your ability to concentrate.
• You feel worse. You are more irritable, are more likely to have headaches, and you are also to have sudden mood changes. Even depression is sometimes part of the symptoms.
• Your immune system is disrupted. This makes you more prone to any type of disease

Then come the symptoms of jet lag that you experience because the circadian rhythm of your organs is not aligned with your new external time:^​1,2,7​

• Your appetite is not aligned with your day. You are not hungry at times when locals eat but you are hungry at times when locals sleep. Plus you also don’t seem to enjoy your food as much.
• Your digestion is not prepared for your new eating times. You are eating when your organs don’t anticipate it and haven’t produced digestive juices yet – making the whole digestion less efficient and take longer. And at other times, your organs anticipate food and produce digestive juices – but then they only have your empty selves to act on.

Lastly, this is the symptom of jet lag that you experience if the circadian rhythm of your tissues and muscles is not aligned with your new external time. But you don’t need to worry too much about it if you’re not an elite athlete:^​2,3​

• Your physical performance is worse. Especially your motor skills. And you also feel more fatigued.

You experience each of these sets of symptoms because their underlying circadian rhythm is disturbed. That’s the root cause.

Now, to reduce how much jet lag you experience, you can either treat those symptoms or the cause. What would you rather do? Thought so, me too. So let’s have a look at how to get your circadian rhythms aligned to your new external time as fast as possible.

Minimize and Beat Jet Lag

What Can You Do to Minimize and Beat Jet Lag

Your key to beat jet lag is to align your circadian rhythms to your new external time. And, as you’ve seen above, you can do this with the help of their zeitgebers.

Or, as Charmane Eastman and Helen Burgess from the Rush University Medical Center wrote in their paper titled “How to Travel the World Without Jet Lag”:^​1​

“The symptoms of jet lag dissipate as the circadian clock is gradually reset (gradually phase shifts) to re-align (re-entrain) to the time cues (zeitgebers) of the new time zone.”

Charmane Eastman & Helen Burgess

Wait, what does that mean? It basically means that your symptoms of jet lag slowly go away the more you are aligned with your new external time. And the key in that process is your zeitgebers – your environmental cues.

You’ve seen above that you have three core circadian rhythms – your central (master) one, the one of your organs, and the one of your tissues and muscles – that each has their own zeitgebers. These zeitgebers are their environmental cues they need to align their internal time to your external time.

And just like this, we know what you need to do to beat jet lag: You need to align your circadian rhythms to your new external time as this is the root cause of jet lag.^​1​

“The most effective treatments for jet lag rely on shifting the circadian clock to the new time zone as fast as possible.”

Charmane Eastman & Helen Burgess

But how exactly can you do that? With the help of their environmental cues – their zeitgebers. That’s the key to align your circadian rhythms to your new external time as fast as possible. Remember that little overview table from above? Let’s have a look at it again:

Core circadian rhythm	Zeitgeber (environmental cue)
Central (master) circadian rhythm	Light exposure
Circadian rhythm of your organs	Eating timings
Circadian rhythm of your muscles and tissues	Exercise and activity

The table above shows you WHAT you need to do to shift your three core circadian rhythms to your new external time as fast as possible:

1. To align your central (master) circadian rhythm, you need to adapt your light exposure
2. To align the circadian rhythm of your organs, you need to adapt you eating timings
3. To align the circadian rhythm of your muscles and tissues, you need to adapt your exercise and activity

Next, I’ll show you HOW you can do it.

If you fly east, then you need to advance your circadian rhythms to match the new external (local) time zone. And if you fly west, then you need to delay your circadian rhythms to match your new external (local) time zone. And for most people, it is easier to delay (aka stay up longer) your day than to advance (aka wake up earlier) your day.^​1​

And to fully beat jet lag, you should already adjust your circadian rhythms towards the new local time zone you are traveling to. Before you take that journey. And then fully adjust your circadian rhythms to their new external (local) time once you’ve arrived.

Let’s get into it now, step-by-step for each of your three core circadian rhythms.

Your Master Circadian Rhythm

#1 Align Your Central (Master) Circadian Rhythm Through Your Light Exposure

Your central circadian rhythm is controlled by a small part in your brain (called your SCN). This part of your brain gets its time of day information from special light receptors in your eyes (called melanopsin). And those light receptors don’t help you see, but they only help you sense the time of day information based on the light they receive. And they then send this information directly to your SCN (the part of the brain that controls your central circadian rhythm).^​9​

You can read all about it in this post: “How Does Your Circadian Rhythm Work” 

Now, your SCN has developed with sunlight as its natural cue about the time of day – its zeitgeber. And that is also the kind of light that it expects to adjust your central circadian rhythm.

And sunlight has two special properties:^​10​

1. The light intensity is crazy intensive during the day and nearly zero at night.
2. The blue-light spectrum is high during the day but not anymore during the evening and not at all during the night.

Why am I telling you about sunlight and its properties? Because that’s the kind of light that your SCN expects to adapt your central circadian rhythm:^​11​

1. In the first part of the day: If both light intensity and blue-light spectrum are high enough (aka at sunlight levels), then your SCN speeds up (advances) your central circadian rhythm.
2. In the middle of the day: Light information doesn’t change your circadian rhythm.
3. In the evening and at night: Already a relatively low light intensity with a bit of blue light is more than your SCN expects (aka anything more than no sunlight). And that leads your SCN to slow down (delay) your central circadian rhythm.

And you might have guessed it right – this is your solution to adapt your central circadian rhythm!

If you fly EAST then you want to speed up (advance) your central circadian rhythm	If you fly WEST then you want to slow down (delay) your circadian rhythm
You need to expose yourself to light in the first part of the day.	You need to expose yourself to light in the evening and at night.
And that light needs to be both high in intensity and blue-light spectrum. Just like natural sunlight.	In this case, any light that is high enough in blue-light intensity does the trick for you.
And you need to shield yourself from light in the evening and at night.	And you need to shield yourself from light in the first part of the day.

It is much easier for your central circadian rhythm to slow down and adapt to a “longer” day if you fly west.^​1,2​ For one, this is because your circadian rhythm most likely is more than twenty-four-hours long.^​12​

And then our modern environments are in favor of slowing down your circadian rhythm. You most likely don’t get enough light exposure during the day and too much in the evening and at night. Just as if you were preparing to fly west.^​11​

So, if you fly east, then you need to speed up your circadian rhythm. Let’s have a look at a few practical – and scientifically proven – tips how you can adapt:

In the first part of the day:

• Spend as much time outdoors – with natural light – as possible, especially in the morning, directly after waking up^​13​
• Stay as close to windows as possible when you are indoors^​14​
• Take artificial light showers if needed^​15​
• Don’t wear sunglasses or blue-light-filtering glasses^​6​

In the evening/ at night:

• Adapt your home lighting (lower intensity lights with less blue-light rays)^​6​
• Reduce screen-time and blue-light emissions from your screens^​16​
• Use blue-light-filtering glasses^​17​
• Avoid any (blue) lights at night^​18​

Unfortunately, those are the things that you are also most likely falling short in your everyday life. Have a look at tips #1 to #9 in the post “Get Your Circadian Rhythm Back on Track: The Ultimate Guide” for all the information you need.

And to slow down your circadian rhythm? Well, that’s actually much easier! Shield yourself as from natural light during the day. And expose yourself to artificial light in the evening.

When you fly east	When you fly west
Before your travels: Maximize your (natural) light exposure in the first part of the day and minimize your (artificial) light exposure in the evening and at night.	Before your travels: Slightly reduce your (natural) light exposure in the first part of the day and slightly increase your (artificial) light exposure in the evening (not at night though).
After your travels: Use all the tactics from above to fully maximize your (natural) light exposure in the first part of the day and to fully shield yourself from (artificial) light exposure in the evening and at night.	After your travels: Further shield yourself from natural light during the day. And expose yourself to artificial light in the evening. Until you’ve fully adapted.

Now, if you adjust your central circadian rhythm already towards your new time zone before you travel, then you are one step ahead of virtually everybody in beating jet lag. And once you’ve reached your destination? Implement the tips from above to get your central (master) circadian rhythm back on track as fast as possible.

In general, your central (master) circadian rhythm aligns much faster to your light exposure than your other two rhythms align to their zeitgebers.^​7,19​

But what about your other core circadian rhythms? I’m glad you’ve asked! Let’s have a look at them next.

Your Organs

#2 Align the Circadian Rhythm of Your Organs Through Your Eating Timings

First things first: the circadian rhythm of your organs only takes more time to align to your new time zone if you don’t adapt your zeitgeber. But if you do? Then it aligns the fastest – as much as double as fast as your central circadian rhythm.^​2,20​

So, what is the zeitgeber – the environmental cue – for the circadian rhythm of your organs? Quite simply, it’s your eating timings. Or, to be more precise, it is when you start eating and when you stop eating.

Why? Because your organs have to start working on your digestion once you consume your first calories of your day. And they have to continue working on your digestion for about two hours after you’ve consumed your last calories of the day.^​6​

And only about two hours after you consumed your last calories (yes, also drinks and small late-night snacks count) can your organs shift their activities towards repairing and rejuvenating themselves.

Here’s a general tip: If you want to live healthier, then you need to allow your organs more time to repair and rejuvenate themselves. In short, stop eating early enough in the evening and eat for fewer hours every day. Check out all about this in tips #10 and #11 in the post “Get Your Circadian Rhythm Back on Track: The Ultimate Guide.”

Ok, back to helping you to beat jet lag. Even though the same applies here.

Here’s what you need to do to align the circadian rhythm of your organs as fast as possible to your new external time zone:

• Restrict your eating timings in alignment with your new time zone.^​2,20​
• Resist your temptation to eat at night. Even if you feel hungry and can’t sleep. Backstory: you feel hungry because of a hormone called Ghrelin. And this hormone has daily fluctuations based on your circadian rhythm and the times when you normally eat. Its daily rhythm will adapt to your new eating timings. And you don’t need to fear any nutrient or calorie deficiencies if you skip eating once when you feel hungry. Especially if it’s at night. And that hungry feeling also goes away by itself after some time – you only have to wait for the levels of your hunger hormone Ghrelin to go down again.^​21​

That’s it! And with this little trick, you can align the circadian rhythm of your organs to your new local time.

When you fly east	When you fly west
Before your travels: Stop eating a little earlier than normal.	Before your travels: Start eating a little later than normal.
After your travels: Only eat during the local eating times. Especially resist any temptations to eat at night.	After your travels: Only eat during the local eating times. Especially resist any temptations to eat too early in the morning.

Now, eating at times when the locals eat is the best way to adapt the circadian rhythm of your organs to your new time zone. And if you do so, then they are not the last to adapt. But the first.

Your Muscles and Tissues

#3 Align the Circadian Rhythm of Your Muscles and Tissues Through Your Activity and Movement

Now, let’s have a look at your last core circadian rhythm: the circadian rhythm of your muscles and tissues. And their zeitgeber? Exercise.^​22​

And depending on when you exercise, you can either speed up or slow down the circadian rhythm of your muscles and tissues:^​23​

• You can speed up their circadian rhythm if you exercise in the morning and early afternoon
• You can slow down their circadian rhythm if you exercise in the evening.

An additional bonus of exercise? It is known to reduce your feelings of hunger. Why? Because it suppresses Ghrelin, your hunger hormone (remember that part about your eating timings from above?).^​24​

Exercise generally follows your circadian rhythm. And some times are better suited than others – depending on what type of exercise you want to do (e.g., easy or high intensity) and what you want to achieve with it (e.g., build muscle or lose body fat). You can read all about it here in “When Is the Best Time to Exercise Based on Your Circadian Rhythm.”

Ok, let’s get back now to how you can beat jet lag with exercise!

When you fly east	When you fly west
Before your travels: Exercise in the morning or late afternoon/ early evening.	Before your travels: Exercise in the evening.
After your travels: Exercise in the morning or late afternoon/ early evening.	After your travels: Exercise in the evening.

Additional Hacks

Additional Hacks: Melatonin, Chocolate, and Cordyceps

Now, before I show you any additional hacks to minimize the effects of jet lag, let’s be clear about one thing: they are no magic pills. And you have the greatest effect to beat your jet lag if you align your three core circadian rhythms to your new local time.

With that being said, let’s have a look at some additional hacks and how you could potentially use them.

Additional Hack: Melatonin

Research indicates that melatonin supplements can speed up your central circadian rhythm if you take them in the afternoon (great after traveling east). And that melatonin can slow down your central circadian rhythm if you take it in the morning (great after traveling west).^​1,25​

How does melatonin work on your circadian rhythm? It is like a hormonal signal for darkness. One that you would naturally produce based on your central circadian rhythm. And also one that has a feedback loop back to your central circadian rhythm. Sleep is just a side effect for you.

That is also the reason why melatonin works differently on us (day-active) than on nocturnal (night-active) animals: For us, melatonin is associated with our sleep phase, but for nocturnal animals, melatonin is associated with their waking phase.^​1​

Either way, you should not take melatonin lightly. And it is not without reason that it still stays prescription only in a number of countries.

Additional Hack: Chocolate

Wait, what? Chocolate against jet lag? Well, yes and no. It depends on when you eat a piece.

You’ve seen above that the first bite of food (or better your first calories of any kind) start the circadian rhythm of your organs. Well, it turns out that chocolate has a special role here.

One timed piece of chocolate in the morning signals your central circadian rhythm the start of your activity phase. In this way, it helps you to align your central (master) circadian rhythm to your new external time zone. At least if you eat your chocolate in the morning, for breakfast. If you eat your chocolate in the evening, however, it has the opposite effect. It makes it more difficult for your central circadian rhythm to adapt to your new time zone.^​26​

Want to know one more interesting thing about the timing of when you eat your chocolate? If you eat your chocolate in the morning, then you are only gaining a relatively low amount of bodyweight. But if you eat your chocolate in the evening, then you gain significantly more bodyweight.

The only drawback is that this has so far only been proven in a rat model. But hey, nothing to lose here! At least if you go with the darkest chocolate you can find. And yes, I’m speaking about 90% and above. You don’t want to eat a lot of sugar with a little chocolate.

Additional Hack: Cordyceps

Have you ever heard about the cordyceps fungus? And that it could also help you with jet lag? I knew well about the many health benefits of cordyceps and regularly drink it as a “tea.”^​27​ But now it seems like I can add one more benefit to cordyceps: adapting to a new time zone quicker!

Cordyceps helps you to align your central (master) circadian rhythm to a new time zone. Remember that light was its zeitgeber (environmental cue)? Well, it turns out that cordyceps binds to an enzyme (called RUVBL2) that is involved in the process that responds to your light signals. And it makes you more sensitive to your new light signals. In this way, light – as your zeitgeber – has a bigger effect on changing your internal time to your new external time.^​28​

And how much is the difference? Well, in first mice studies, the adaption – aka jet lag – time was cut in half! In a lab scenario, those mice effectively traveled across eight time zones. Either forward (to the east) or backward (to the west). How long did they on average need to adapt to their new environments? The control group needed a full eight days. But the cordyceps group? Only four! And that for either direction.

Full Implementation Plan

How You Can Implement All Scientifically Proven Ways to Beat Jet Lag

You have seen above that you have three core circadian rhythms that you need to align with your new (external) local time zone. And each of these core circadian rhythms has its own zeitgeber – its environmental cue that it needs to adapt its internal time to your external time.

• Your central (master) circadian rhythm adapts based on your light exposure.
• The circadian rhythm of your organs adapts based on your eating timings.
• The circadian rhythm of your muscles and tissues adapts based on your activity and exercise.

Ok, let’s bring it all together in one simple overview. Shall we?

	What to do if you fly east	What to do if you fly west
Before your travels	Light: Maximize your (natural) light exposure in the first part of the day and minimize your (artificial) light exposure in the evening and at night. Food: Stop eating a little earlier than normal. Exercise: Exercise in the morning or late afternoon/ early evening.	Light: Slightly reduce your (natural) light exposure in the first part of the day and slightly increase your (artificial) light exposure in the evening (not at night though). Food: Start eating a little later than normal. Exercise: Exercise in the evening.
After your travels	Light: Use all the tactics from above to fully maximize your (natural) light exposure in the first part of the day and to fully shield yourself from (artificial) light exposure in the evening and at night. Food: Only eat during local eating times. Especially resist any temptations to eat at night. Exercise: Exercise in the morning or late afternoon/ early evening.	Light: Further shield yourself from natural light during the day. And expose yourself to artificial light in the evening. Until you’ve fully adapted. Food: Only eat during local eating times. Especially resist any temptations to eat too early in the morning. Exercise: Exercise in the evening.
Additional hacks (all after your travels)	Melatonin: Can speed up your circadian rhythm if taken in the afternoon. Chocolate: Eat a piece in the morning to signal the start of your activity phase. Cordyceps: Use throughout your day, especially in the morning and evening.	Melatonin: Can slow down your circadian rhythm if taken in the morning. Chocolate: No adaptation benefit. Only signals start but not end of your activity phase. Cordyceps: Use throughout your day, especially in the morning and evening.

Great, now we got that covered. But how long does it take until your three core circadian rhythms have adapted to their new external time?

Time to Full Alignment

How Long Does It Normally Take to Align Your Circadian Rhythm With a New Local Time Zone

Well, how long it takes for your circadian rhythms to adapt to a new time zone depends on a few factors. Most notably:

• Did you fly east or west?
• How many time zones did you cross?
• How strong are your zeitgebers?

Let’s start with something that impacts how you adapt when you cross time zones: the length of your central circadian rhythm. Which most likely is more than twenty-four-hours long. At least if you belong to the vast majority.^​12,29​

Want to find out how long your circadian rhythm is? Check it out here: “How Long Is Your Circadian Rhythm”

With a longer circadian rhythm, you need to adapt relatively less if you fly west and your external day gets relatively longer. And with a shorter circadian rhythm, you need to adapt relatively less if you fly east and your external day gets relatively shorter.

But there’s more to it.

When you fly east, then your circadian rhythms need to speed up. And when you fly west, then your circadian rhythms need to slow down. And, on average, your circadian rhythm adapts much faster when it needs to slow down (for longer days, flying west) than when it needs to speed up (for shorter days, flying east).^​1​

“The circadian clock phase delays faster than it phase advances.”

Charmane Eastman & Helen Burgess

Just think about it from this perspective: If you are like the majority, then it is much easier for you to stay up late than to sleep early. And to wake up late than to wake up early.

How much easier – or better, faster – do you adapt to your new external time when you fly east vs when you fly west? Let’s have a look at three studies and put some numbers behind:

Circadian rhythm adaptations	Speed up (fly east)	Slow down (fly west)
Study 1 (1975)​30​	57 min/day	92 min/day
Study 2 (1992)​31​	93 min/day	144 min/day
Study 3 (2003)​32​	90 min/day	120 min/day

Now, what’s the first thing that you can see? Your circadian rhythm adapts much faster when it needs to slow down than when it needs to speed up. About fifty percent faster.

And the second thing? In the two later studies (1992 & 2003), the circadian adapted much faster in both directions than in the first study (1975). The explanation for this? Intensive light exposure! You’ve seen before that light is the zeitgeber (environmental cue) for your central circadian rhythm. And now you can also see in numbers how important it is to align you with your external time.

Let me emphasize this last point again, by quoting Till Roenneberg, one of the leading chronobiologists of our time:^​7​

“The stronger you can make the new zeitgeber, the faster your body clock will arrive at the new destination.”

Till Roenneberg

Now, when you travel to a new time zone and don’t use light to your advantage, then you need about a day or two-thirds of a day to adapt per time zone crossed. But when you only use light to your advantage, then you can drop this number to about two-thirds of a day to half a day per time zone.

Ok, those numbers were for your central (master) circadian rhythm. But what about your other two core circadian rhythms? Those of your organs and your muscles and tissues? No need to worry about their timing, because they adapt much faster. At least if you keep their zeitgebers strong. Just like in the tips from above!^​2​

And if you implement all the tips and hacks from above? Then you’ll be able to minimize your jet lag as much as possible! Or fully beat it, if you don’t cross too many time zones!

Additional Impact Factors

Which Additional Factors Impact How Successful You Beat Jet Lag

Are you still with me? Good! Cause in this section I’ll show you a few additional points that you might want to watch out for.

But don’t worry, above you’ve seen everything you need to beat jet lag. What I’m going to show you here are some common misconceptions as well as additional factors that impact your jet lag.

Drugs

Drugs Only Mask the Symptoms Jet Lag

You have seen the cause for jet lag above. But what you experience during jet lag are its symptoms. And for some, drugs might sound like a quick fix here.

But – and that’s a big but – the reason why you experience jet lag still stays the same. You need to align your circadian rhythms to your new time zone. Taking drugs like caffeine, to feel more awake, or sleeping pills, to fall asleep, don’t help with that. Instead, they only mask the symptoms of jet lag.^​1​

Björn Lemmer, from the University of Heidelberg, stated the following in his article titled “The sleep-wake cycle and sleeping pills”:^​33​

“Symptoms from jet-lag are due to an internal desynchronisation of biological rhythms […] The biological clock(s) cannot be reset instantaneously by any drug.”

Björn Lemmer

The underlying problem still exists as long as your circadian rhythms are not aligned with your new time. And for that, you need to adapt your light exposure, your eating timings, and your exercise.

Only masking the symptoms of jet lag with drugs – while experiencing potential side effects, a real risk for abuse and dependence, reduced cognitive function, impaired adaptation to your new time zone – simply doesn’t do the trick. Especially not since you know better now.

Travel Fatigue

Don’t Mistake Jet Lag for Travel Fatigue

Speaking about things that don’t do the trick to help you beat jet lag: fighting the wrong game. And in this case, it is confusing travel fatigue for jet lag.

Travel fatigue comes from the journey itself. Jet lag comes from arriving at a new time zone.

Travel fatigue does add to the symptoms of jet lag. And because it appears pretty much at the same time, it is easy to mix those two together to one. Or, to be more precise, travel fatigue builds up during your journey, while jet lag starts when you’ve arrived and your circadian rhythms receive different signals from their zeitgebers (environmental cues) than they expect. And from your time of arrival, they both overlap:^​2​

• The causes of travel fatigue are things like you being in a tight space, not moving as much as normal, generally being at least slightly dehydrated, staying in a pressurized cabin, and with disturbed sleep and normal routine.
• What helps combat travel fatigue is to leave home well-rested, drink plenty of water, and get up from your seat regularly to move (and then some more).
• The time travel fatigue stays with you is mostly just one day. It is usually gone the day after. But jet lag still stays with you for longer.

Want to appreciate the full impact of travel fatigue without any jet lag? Take a long north-south journey without crossing any time zones. Full-on travel fatigue without any jet lag. And in this way, you’ll also appreciate that you’ll have fully recovered again the very next day.

Experience

Your Travel Experience Doesn’t Prevent Jet Lag

Unfortunately, your body doesn’t just get used to crossing time zones (just as if that never has been an evolutionary advantage). Jet lag will still appear.

Don’t want to take my word for it? Then may I convince you with aircrew members? Even though they regularly cross time zones, their bodies never get used to it. And if they don’t adapt, then they still experience all the symptoms of jet lag.^​34​

It’s not the experience of their body that makes them cope with jet lag. It is their experience to know what helps them best that makes them minimize jet lag. But luckily, now you know it all as well.

Correlation vs Causality

Your Previous Experience With Jet Lag Might Be in Your Way

Speaking about experience and what helps you minimize jet lag. Your experience might actually work against you.

Wait… What?

Yes, because many people have superstitions about what helped them overcome jet lag in the past. This is a typical case of correlation vs causality. Just because something happened at the same time (correlation) doesn’t mean that it is the reason for something else (causality). Now, if you think back about your previous travels, what do you think it was that helped you?^​2​

Your time of arrival in a new time zone and the light exposure you get in the first days have a big impact on how much jet lag you experience (causality). Even if you don’t take any steps to beat jet lag. And if you took any steps to beat jet lag?

Then they might just have happened at the same time (correlation) without actually helping you to beat jet lag. Or they helped you to overcome travel fatigue. This helps you feel better but happens anyway after a day or so. But it doesn’t help you overcome jet lag.

Want to go all-in with causality? Have a look again above at the scientifically proven ways to beat jet lag.

That being said, also be cautious with sleeping during your flight. Avoid it unless it is night at the local time of your destination.

Core Body Temperature

You Don’t Want to Mess With the Circadian Rhythm of Your Core Body Temperature

Do you remember from before that also your core body temperature has a circadian rhythm? And it is normally lowest just about halfway into your sleep.^​35,36​

But there’s more to it:

• You have difficulties sleeping at times that are too far away from your low point in core temperature.^​37​
• You can only get high-quality sleep in the about six hours before and after your low point in core body temperature.^​38​
• You experience the worst jet lag symptoms when the low point of your core body temperature falls into your waking period.^​1​

Those are three key reasons why you need to shift your circadian rhythm already before you travel. Especially when you travel across too many time zones.

One more thing about sleeping. You should only sleep during your flight if it is night by local destination time. Otherwise, avoid it. Even though you get the highest quality sleep when you feel most tired (aka your core body temperature is lowest), you don’t want to risk anchoring your circadian rhythms to your old time zone – while you are already on your way to your new time zone.^​2​

Age

The Older You Get the Less You Can Cope With Jet Lag

The older you get, the less you are able to cope with traveling across time zones. And the more severe symptoms of jet lag you will experience.^​39,40​

But not all is lost. It turns out that this comes mainly from difficulties adapting to new sleep times. Especially after flying eastwards. While the other markers of your circadian rhythm (like the rhythm of your core body temperature) don’t adapt any worse the older you get.

In this special case, you might actually want to speak with your doctor about additional aids to help you fall asleep. But still remember, that this still only temporarily helps you with one symptom of jet lag. Not with any of its root causes.

Daylight Savings Time

Daylight Savings Time Is Like Jet Lag but Without Crossing Time Zones and Without a Change in Zeitgebers

Have you ever wondered how you can experience jet lag without traveling at all? Well, welcome to daylight savings time!

Twice a year, your external time changes by one hour. And I could bet that you feel worse when you “lose” one hour. Just as if you crossed one time zone to the east.

The only problem is that your most important zeitgeber – your natural light exposure – stays virtually the same. And that makes it much harder for you to adapt your central (master) circadian rhythm to your new time.

But if you treat the change to or from daylight savings time just as traveling one time zone east or west, then you can also beat it. Instead of it beating you up for a few days. Just follow the tips from above and you’ll have the opportunity to experience how powerful they are – twice every year.

Short Travels

When Not to Adapt to a New Time Zone

Is there a case when it’s more beneficial for you not to adapt to a new time zone? Yes, there is!

When you only travel for a few days (for most people, fewer than three days) then it is more beneficial for you to remain on your home time. For these very few days, you will experience jet lag. But that shouldn’t be a problem if you just continue to live as close as possible to your home time. Knowing that you’ll be fine again immediately when you return.^​2​

If you try to adapt twice for such a short stay, then you might create yourself a special case where the cure is worse than the disease (aka your jet lag symptoms).

Personal Experiences

My Personal Experiences

Let me share with you what has helped me adapt to new time zones in the past. With one concrete example of traveling to Iten, Kenya.

Now, the difference in time was only one hour. But my day there started an additional three hours earlier. So I was effectively traveling four time zones. And all of those were to the east, meaning that I had to speed up my circadian rhythm(s) by four hours.

Now, did I have any issues with jet lag? Nope, not at all. And here’s why:

• Light exposure: I was running every morning, starting around 6 am, just when the sun came out. One hour full natural light exposure. I also stayed outside most of the day and was tired and spent once it got dark. That dramatically cut down my artificial light exposure in the evening and at night.
• Eating timings: In Iten, I stayed with a local family and also ate together with them. That doesn’t just mean that I was able to eat delicious local food, but also that I was eating at local times. Besides breakfast, I skipped those.
• Exercise: Oh yeah, that’s what I was actually there for. I ran every morning. And mostly did a cycling or swimming session in the afternoon. If not another run.

Altogether, I was lucky that my natural lifestyle already included all the scientifically proven ways to beat any possible jet lag. And it felt great to make that shift of effectively four hours without any problems.

Quite the contrary actually. All the outside activity was such a difference to my indoor desk job that I felt much better in the end. But that’s a story for another time.

My big takeaway is that it is great knowing how to beat jet lag in theory based on scientifically proven ways. But it is even better to also implement those ways and see it working for myself.

And to then share it with you. Hoping that you’ll have the same success beating jet lag from now on!

Key Takeaways

Key Takeaways

Finally, there are four key takeaways that I want to share with you to beat your jet lag:

1. You experience jet lag because you have arrived in a new time zone but your circadian rhythm(s) don’t know that yet. They still try to optimize the timing of all your body functions based on their internal time. That leads to two main problems
   • Your central (master) circadian rhythm is not aligned with your external time.
   • Your three core circadian rhythms are not in harmony.
2. You have three core circadian rhythms that each have their own zeitgebers (environmental cues) to adapt to your new local time zone
   • Your light exposure is the zeitgeber of your central (master) circadian rhythm.
   • Your eating timings are the zeitgeber of the circadian rhythm of your organs.
   • Your exercise and activity are the zeitgebers of the circadian rhythm of your muscles and tissues.
3. You can beat jet lag if you leverage the zeitgebers of your three core circadian rhythms to align them to your new local time zone
   • Start shifting your circadian rhythm(s) already towards your new local time zone before your travels.
   • Implement all tips to maximize your zeitgeber exposure at the right times as soon as you’ve arrived at your new time zone. Seriously, have a look at all the tips from above again in the implementation plan. This is your scientifically proven way to beat jet lag. 
   • If needed, you can use melatonin, chocolate, and cordyceps as additional hacks to speed up the alignment process. But don’t count on them as any kind of magic pills. Cause they are not. Nothing will help you as much as the zeitgebers of your three core circadian rhythms.
4. How fast you align to a new time zone depends on how strong you make your new zeitgebers. In general, you align much quicker if you fly west than if you fly east.

And now back to you: If you reflect on your travels, how quickly do you normally overcome jet lag? And have you noticed anything different in the past between flying east and flying west? Now, implement all those changes the next time you cross time zones and feel for yourself how much of a difference it makes. And feel happy to know that from now on you are able to beat jet lag. On every single journey.

Stay fit,

PS: If you found this information useful, spread the word and help those who would benefit most from it 🙂

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