Many jobs involve frequent travel and in a stressful lifestyle, jet lag can be our worst enemy. The desperation we feel when we know we need to catch a couple of hours of sleep before the crucial meeting or flight tomorrow but can't, is all too familiar. Our head feels like it's held by a vice grip, we lose mental sharpness and the process of thinking feels foggy.
One reason why the underlying cause of jet lag has remained so elusive is because we are only just beginning to understand how our body's clock works. We used to think we had one big body clock nestled somewhere in our brain, telling us when to wake up every morning and when to fall asleep. Recent research shows that this is in fact not true. All of this time, we were only looking at the tip of the iceberg. Our body contains hundreds of thousands of clocks. Our liver has its own clocks, our heart has its own clocks and even our brain has several different clocks scattered around its various regions. One main 'central' clock sitting in the Supra-Chiasmatic Nucleus in the brain is like the maestro conductor of this orchestra of clocks. It sends signals through various pathways to keep the clocks ticking in synchrony. The clocks scattered around various organs of the body are collectively termed the 'peripheral clock' or 'peripheral clocks'.
We think that jetlag happens when the central clock gets uncoupled from the peripheral clock. The central clock is sitting right behind the eyes and light coming in through the eyes (specifically light at approximately 479nm wavelength coming in through a specific type of light receptor in the eyes known as melanopsin containing ganglion cells - which are also responsible for the pupil reflex!) entrains the central clock. The peripheral clocks don't have the luxury of light receptor signals and need to wait for light information to reach them via hormones and other signals. Instead, the peripheral clocks respond to other cues which signal what time of day it is. One particularly potent cue is known as the 'fasting-feeding cycle'.
The fasting-feeding cycle refers to the phenomenon whereby if you don't eat for say 8-12 hours and then have a large meal, that meal tells your peripheral clock that it is 'breakfast time'.
When you are in a different time zone, the ambient light tells your central clock about your new surroundings and your central clock starts adapting to your new destination. Your peripheral clock does not receive this direct light information. It must wait for the information being sent by your central clock after it has gone through various nerve and hormone signals. We think that this lagging behind of your peripheral clock until it finally catches with your central clock forms the basis for jet lag.
In order to to avoid jet lag, you need to start tuning your peripheral clock before you set off, so that it gradually adapts to the time zone of your destination by the time you arrive. Once you arrive, your central and peripheral clocks will then stay coupled and you will not suffer jet lag.
You can tune your peripheral clock using the fasting-feeding cycle. A few days before you leave, start fasting for 8-12 hours then eating a large meal when it is breakfast time at your intended destination. Do this every day and keep this up on the plane. Remember, your central clock is the maestro conductor, it is the main time-setter for the rest of your body and the fasting-feeding cycle will not be affecting your central clock too much. So, doing this for a couple of days before you leave should not make you feel reverse-jet lagged, as incoming daylight will continue to keep your central clock in synch with your current location. Adopting this fasting-feeding cycle will instead start gradually and gently entraining your peripheral clock to your destination, so it becomes easier for your peripheral clock to synch with your readjusted central clock when you arrive.
Once you arrive, make sure you expose your eyes to daylight in order to entrain your central clock. With this approach both your central and peripheral clocks will rapidly synchronise upon arrival at your destination and you might be able to completely avoid jetlag!