Hacking jet lag

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Let’s face it, jet lag sucks.  It messes with your energy, focus, digestion, immune system, and disturbs your blood glucose regulation.  So anything you can do to prevent these negative effects when you have to travel across time zones will make you healthier and more robust.

The physiological consequences of jet lag are due to the desynchronization of internal timekeepers found in all of your organs and tissues called circadian clocks.  These clocks function to optimize physiology by synchronizing communication between cooperating systems. When the timing between cooperating systems is disturbed, physiology takes a turn for the worse.

For example, your blood glucose is regulated by a large number of tissues including your liver(makes and releases glucose), gut(increases glucose absorption from from food), pancreas(secretes insulin and glucagon), adrenals(secretes stress hormones), muscles and fat(take in glucose), and the brain(increases hunger to motivate search for food).  When you eat food, glucose gets absorbed from the gut and the pancreas secretes insulin to drive excess glucose in to the liver, muscle, and fat cells.

When you’re fasting, the adrenals secrete stress hormones that cause the pancreas to secrete glucagon which tells the liver to release its stored glucose to maintain adequate blood glucose levels.  Ghrelin is secreted from the empty stomach and motivates you to find food.  All of these processes are dependent on proper communication and timing to maintain healthy blood glucose regulation.

While the circadian clocks beat to their own rhythm, they’re reset on a daily basis by environmental exposures called zeitgebers, or time-givers.  This is why jet lag sucks so hard.  You leave NYC at 8pm your time and arrive in London at 8am their time, but the flight is only 7 hrs long.  Your clocks think it’s 3am but when you get off the plane the sun is shining.

Fortunately if you use the science there are a few things you can do to prepare to limit the disruption.  By following the 5 steps below, you can enjoy your vacation or crush your business presentation while feeling great.

Prepare in advance

The first step is to determine how many time zones you’ll be crossing.  It takes 1 day per time zone crossed to adjust to a new time.  So in the example above, you’ll be crossing 5 times zones and will want to prepare 5 days in advance.  This will allow you to shift your clock 1 hour each day.

Optimize light exposure

Our master circadian clock, located in an area of the brain called the suprachiasmatic nucleus(SCN), is regulated by light exposure.  Modify your light exposure by 1 hour each day by exposing yourself to the Sun in the morning and blocking blue light at night an hour later/earlier.  Use blue blocker glasses at night and if you’re traveling to a later time zone you may need a light box to simulate daylight if it’s still dark where you live.

Shift your meals

While the master clock is regulated by light exposure, the other clocks throughout your body are primarily regulated by the feeding/fasting cycle.  Along with adjusting your light exposure an hour a day, you should also adjust your feeding/fasting schedule by the same.  To optimize circadian rhythms, your eating window should be less than 12 hours every day.  If your not paying attention to this, start now!

Use prolonged fasting

Using a prolonged fast(>24 hours) is also a useful strategy to synchronize your clocks in a pinch.  After prolonged periods of fasting, your clocks are very sensitive to entraining to the new feeding time.  It’s still a good idea to plan out based on an hour per day per time zone, but this allows you to compensate if work or family obligations don’t allow a 5 day lead in.

Utilize factors that modulate stress

It’s far easier to go back a few time zones than it is to move forward because most people can stay up and wake up a little later than doing the opposite.  To help take the edge off, use stress inducing factors such as exercise or coffee in the morning and stress reducing factors such as meditation or yoga at night to force the change as you shift.  The more you do the easier the process.


Jet lag isn’t an inevitable consequence of crossing time zones.  By preparing in advance and following the 5 steps above, you can limit or even eliminate the ill effects of jet lag.

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