Or how to tackle jet lag.

Do you like flying? Or do you consider flying a necessary evil to get to your destination?

Me, I love flying. I love planes, even when I am not in them. Just seeing them fly gives me a sense of awe and freedom. Hearing them fly over does so too. I don’t like the hassle that precedes the flight, but as soon as I am checked in and at the gate, my sense of adventure is always present, no matter what my destination is.

But there is this one other thing -a quite annoying one if you ask me- that comes with the game, and that is the infamous jetlag.

We all suffer from it, more or less. Some hate it so much that they refuse to fly through time zones all together. Others live through it as if there is no such thing as time. Most of us are somewhere in between. Flying east is harder than flying west, as we can force ourselves to stay up longer, but we can’t just fall asleep when we want to.

There are all kinds of tips and tricks to get over it, some might take the edge off it, but most don’t really work. But there is one that might just do the trick. Let’s dive into that.

There is this thing called the circadian rhythm. I find this fascinating : up until recently I had never heard of it. It is a 24h cycle that is like the internal clock in our body, that regulates our sleep/wake rhythm. You can call it the master clock in our brain. It is related to the cycle of day and night and is influenced by various factors, of which the most important one is (sun)light. It is related to body temperature, which goes up in the morning, and then down in the evening when we get sleepy and go to bed, and then up again just before we wake up.

Before we had artificial light, the circadian rhythm was running parallel to the actual day and night. Unfortunately artificial light messed this all up. And so do time zone travels.

Now what exactly is jet lag? It is this situation when your circadian rhythm is running on a different schedule than day and night at the location you are in. In other words, you are dead tired when you should be active and wide awake when you should be sleeping, you can’t fall asleep when is bedtime or are up way before dawn, or when it’s almost lunch time. It is terribly annoying and extremely tiring.

Now the interesting news is that you can shift your circadian rhythm, and thus get over or prevent jet lag. Let’s find out how.

The circadian rhythm is related to our body temperature. First of all you must find out what your temperature minimum is. That is that moment your body temperature is the lowest. Usually this is around 90 to 120 minutes before you wake up. To get to know your temperature minimum you take the average wake up time of the last 3 to 7 days, then deduct 90 min to 2 hours and that is your reference point.

For example, if your average wake up time is 7 am, then your temperature minimum is somewhere around 5 and 5:30 am.

Now the idea is to shift that time forward or backward, depending on where you are traveling to. If you expose yourself to bright sunlight up to 4 hours after your temperature minimum, do physical exercise or eat, you will shift your clock and will wake up earlier the next morning. In my example you should do this between 5 am and 9:30 am. That is what you should do a few days before and the first days after traveling east.

If you expose yourself to bright light 4 to 6 hours before that time, do intense exercise or eat, in my example between 11pm and 5am, your clock will shift in the other direction, or , which is what you should do when traveling west.

Of the 3 triggers ; light, food and exercise, the exposure to light is the most efficient. To shift your clock you need direct sunlight. This means you should either go outside or open your window and look towards the light (not directly into the sun though) for 5 to 20 minutes, depending on the brightness. It does not need to be sunny, the light on clouded days is as efficient. Artificial light just isn’t strong enough and windows lower the intensity of light significantly, so make sure to go outside!

Another way to shift your clock is to manipulate your body temperature. You can do that by taking a hot shower (body temperature going down) or cold shower (temperature going up), in either morning of evening.
Let’s give an example. Imagine you wake up at 5 am, it is way too early. You take a hot shower, thus your body temperature will go down and your temperature peak (your highest temperature), will be later in the day. This also means you will get sleepy later and wake up later the next morning. A cold shower has the opposite effect : your body temperature goes up, your peak will be reached sooner and will go down faster : you will want to go to bed earlier and wake up earlier.

As soon as you arrive at your destination, you should eat at the local times. Even if you feel like it’s breakfast time and you crave for a coffee : if it’s around noon you should have lunch, and you should not give in to midnight cravings.

Of course, next to the jetlag there is also the travel fatigue, you are not just tired because of the time difference, but because you had a long flight, you didn’t sleep (well), you had to wake up really early to catch that plane etc. Trying to get control over your circadian rhythm will get you back on track a lot faster!

Having said this : I will be traveling east in a couple of days, the time difference is only 5 hours, but but I need to shift my clock 6 hours. Starting tomorrow, instead of having my coffee in the near dark of my apartment and slowly wake up, I will be jumping on my bike (direct sunlight) and ride to yoga (physical exercise). I will make sure I don’t eat or I am not exposed to light (cell phone or any other type of light) after 11:30 pm.

Let’s see how that goes…

For more information on this topic, check the Hubermanlab podcast, where the neuroscientist Andrew Huberman goes through it in detail!

Photo by Joyce Romero on Unsplash