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What is Happening with Jet Lag?

Jet lag is a temporary misalignment between the circadian clock and the destination time zone and sleep\wake cycle.

In other words, jet lag occurs from travel across multiple time zones and then, following the local time, a change in your sleep/wake cycles.

Jet lag is terrible. So much so that people who travel over 12 hours, can feel jet lag effects for 8 days after arrival. These effects include:

  • Difficulty initiating or maintaining nighttime sleep
  • Daytime sleepiness
  • Decreased alertness
  • Loss of concentration
  • Impaired performance
  • Fatigue
  • Irritability
  • Disorientation
  • Depressed mood
  • Gastrointestinal disturbance

TLDR; It can impair your judgment.

Before we get into some mechanics of jet lag, here are some terms that you may find helpful:

Phase Advance of the circadian clock: Flying East

Phase Delay of the circadian clock: Flying West

Tmin: Temperature minimum, under normal circumstances, Tmin occurs about 3 to 4.5 hours before wake time with an 8-hour sleep episode.

Let’s use some of these terms and put some meaning behind them.

Phase advance is saying that when traveling east your circadian clock needs to be set EARLIER because your bedtime comes up sooner, thus advancing your bedtime. Phase delay, conversely, comes up when you travel west and you need to set your bedtime LATER.

Here’s an example of what such a situation would look like:

If you flew east 7 time zones (e.g. Chicago to Paris) and expect to go to sleep at midnight in Paris, you are really trying to go to sleep at 5:00 pm according to the time of your circadian clock, which is still on Chicago time. You are trying to go to sleep earlier to advance the time of your sleep, yet your internal circadian clock has to phase advance to re-align with your advanced sleep schedule and the new local time.

So, in this example, you would need to phase advance your sleep to occur earlier before you travel to avoid the effects of jet lag. Let’s go over some things about changing your sleep.

The first thing I would imagine myself thinking is, ok I’m going on a trip to Germany I ought to change my sleep schedule all at once and bite the bullet of jet lag earlier so that I can enjoy or perform better on my future trip. In that scenario, I would essentially be experiencing jet lag at my home and reap all of the consequences. But there is a way to plan ahead and not experience jet lag AT ALL!

First, let us make no illusion that this will be a quick change. Your circadian rhythm is a slow-moving mechanism…. Like really slow. But just how slow?

When resetting or re-entraining the circadian clock, the general rule of thumb is this:

  • Circadian clock phase delays 92min\day after westward flights
  • Circadian clock phase advances 57min\day after an eastward flight

Another way to think about this is that if you’re trying to move your bedtime earlier (flying east), you should move your sleep back each day by about 57min. If you’re going to be making your bedtime later (flying west), you can move your sleep each day by about 92min.

So with some planning ahead, you can now perform the most crucial step in solving your jet lag issues. And if THIS is all you get from reading this post, then you’re already way ahead of the jet lag game.

This next part will go over some techniques to help you attune to your new destination timezone quicker and more effectively.

The biggest one of them all is LIGHT EXPOSURE.

The circadian clock can phase shift faster when people are exposed to bright light at the appropriate time. Bright light can help produce phase advances when applied late in the sleep episode & in the morning after Tmin. Bright light can help you phase delay in the evening time as well; you probably have experienced this if you’ve been up past your bedtime looking at your phone, computer, or watching TV.

Now I know about now you’re thinking. Fuck it, I have drugs like caffeine, hypnotics, or even large doses of melatonin, but those treatments will not eliminate jet lag.

According to research: while hypnotic medications can improve sleep quantity, sleepiness will still be felt around the Tmin when it occurs during waking hours. Caffeine can be used during the day, but even moderate doses taken well before bedtime will impair sleep (effect may be overridden by further uses of hypnotics).

Furthermore, stimulants much like caffeine, modafinil, even bright light exposure, and prophylactic naps can all improve alertness and performance but do not return them to normal levels. Hence the underlying circadian misalignment persists.

Meaning that if you don’t give attention to the methods that directly affect your circadian rhythm, (gradually moving your sleep time) all other solutions are essentially like putting band-aids on a large cut. You can keep adding more, but if you need stitches you’ll still be in rough shape.

The Headache of Planning Ahead

This last section is a check-list of things that you can do to improve your trip. Even choosing a few can make a great difference, so don’t feel overwhelmed and try picking a few for the next time you plan on traveling.

There is a lot you can do to prepare for a trip, but just planning ahead can help reduce stress(and cortisol), ensuring that you are functioning at your peak capabilities.

Prep Before Travel

  • If traveling a great distance (many time zones), try to arrive in the morning time. This will help you to obtain as much natural (local) light as possible.
  • Pack early (reduce stressors the day of)
  • All sleep devices ready (face mast, earplugs, lightbox, etc.)
  • Be well rested before the trip (week coming up to trip)
  • Exercise before the flight, stretch during, exercise after the flight


  • Comfy clothes (nothing that is too tight, restrictive of blood flow)
  • Loosen shoes (or take them off should you not smell!)
  • Avoid alcohol, caffeine, as they are diuretics, leading to dehydration
  • Try to ‘clear your ears’ (close mouth and gently putting pressure on eardrums)
  • Antihistamines and decongestants are good (gum also works)


  • Short on short flights, Long on longer flights
  • Make sure to wait until the last leg of the journey (especially if you were able to make it to your destination in the morning).
  • No longer than 30–45minutes (as any longer would put you into a deep sleep)


  • Ask for: Designated quiet areas
  • Aka quiet rooms (usually have some available)
  • Spa facility (gym)
  • For working out and de-stressing. Anything to minimize cortisol.


  • Utilize your ‘home-time’ (home time-zone).
  • Plan meetings so they fit your home-time midday, as this is when you should be at your optimum.
  • This is mainly helpful for shorter stays 3–4 days when there is not enough time to adjust to the local time zone.
  • Get as much natural light as possible during the day.
  • Take naps (10–20min). As many of these as you need. A longer nap duration will get into your sleep phases, leaving you tired when (if) you wake up during them.
  • Be strict on when you drink caffeine.
  • Drink one glass of water for every alcoholic drink you take
  • Relax for 10 min before bedtime
  • More stress = longer relaxation period before bed
  • Exercise at the right time
  • Evening — light workout is good. Just 10–20 min could be enough.
  • Morning — hard workout is best.
  • Eating at similar times to home will help keep your energy consistent.

There are a lot of things to keep in mind here, but if you take the time to strategize and start moving your sleep time in preparations for your trip, you’ll certainly see and feel the difference.

Hope you all enjoyed the read and remember,

Sleep well!

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