I’ve always wondered why we are more likely to feel sleepy at night and can afford to stay awake during the day. I was particularly intrigued why people who travel across numerous timezones experience jet lags.
A good knowledge of geography lets us know that we can only be said to cross timezones if we move east to west or west to east. We do not particularly cross timezones when we move north to south or south to north.
You take a journey which requires you to cross as many as eight timezones and you certainly arrive at your destination feeling tired, having sleep and stomach disturbances, an unwell feeling and a lack of concentration. Well, you may have just experienced jet lag
You only got to experience this cause traveling across so many timezones and gaining or losing time in the process has confused your biological clock. We have many biological clocks but here I am talking about the circadian rhythm.
The circadian rhythm is chief decider of when you fall asleep and why you stay awake. It is majorly controlled by zeitgebers. These zeitgebers are environmental factors that influence our biological 24 hours day/night cycle. The body however has a master clock that determines the circadian rhythm.
This master clock is located in the hypothalamic region of the brain. Popularly known as the suprachiasmatic nucleus (SCN), this aggregation of over 20,000 neurons works in tandem with the retina via the retinohypothalamic tract to determine when there’s daylight and when there isn’t.
When the eyes are exposed to sunlight, the photosensitive cells popularly known as melanopsin present in the retina detects this sunlight and relays information to the SCN. Since we tend to be exposed to sunlight at specific times during the day, the SCN stores that time using it in setting our 24 hour light/dark cycle.
The SCN on getting the information from the retina tells the pineal gland to reduce its secretion of melatonin (a hormone which causes us to sleep) to keep us awake. Correspondingly, during the night time, the secretion of melatonin increases as the SCN receives less information from the retina. It therefore tells the pineal gland to secrete more so we can easily call it a day.
A circadian rhythm is established as this happens within a 24 hour period. So our body tells us to sleep at roughly the same time and wakes us up at almost the same time everyday.
Basically every cell has a circadian rhythm although not totally in relation to sleeping and staying awake. The circadian rhythm also helps in controlling metabolism as cells know that they have to release nutrients into blood while we are sleeping to enable us stay alive during that period. The body also knows to increase its body temperature as we approach so as to make us much more metabolically active and more likely to wake and stay awake.
Okay. Your body knows when to sleep and when to wake up. Quite amazing I’ll say but unfortunately, the earth is not static and The Sun doesn’t have an on and off switch so basically, we can’t have days and nights at the same time across all portions of the earth.
Let’s imagine you are going on a 9 hour journey to a region that is 6 hours ahead of your place of departure in time. You decided to leave by 4 pm and well, your biological clock expects you to arrive by 1 am so all it’s metabolic processes and temperature regulation are carried out in the aim of having you asleep at the end of your journey,
But the gag is, you’ll end up arriving at 7 am. Your body however is not in sync with this and has already prepared towards your sleep according to its schedule. You want to be awake but sleep is inevitable as melatonin has already been secreted in high amounts, body temperature has already been tuned down and metabolic processes have been slowed down. In this state, you are considered to be jet lagged. It will also only make sense to say now that if we didn’t have biological clocks we wouldn’t experience jet lags. Rightly so.
The body has to adjust to its new time zone and this can take days to weeks. It is widely thought that it is much harder to recover from jet lags that result as a consequence of traveling eastwards than the opposite. This is due to the fact that the body has to advance its clock after an eastward journey which is considerably harder as opposed to having to delay it after traveling westwards which is considerably easier.
Since light is the chief controller of the circadian rhythm, regulating your exposure to light could be instrumental in controlling JetLags as you can adjust your biological clock in preparation for the timezone of your new destination.
It is especially important to avoid alcohol and caffeine while traveling across timezones as they can disrupt sleeping patterns making your jet lag worse than it should be.
Changing the time on your watch to the time of your destination can also be helpful as it prepares your mind for the shock you are supposed to receive and this can act as a good starting point in reducing jet lag.
Taking oral supplements of melatonin is also important where you need to sleep desperately especially when your body is fighting sleep as a function of your circadian rhythm.
Moving rapidly across different timezones could come with consequences as your circadian rhythm is messed up in the process. The SCN is central to the circadian rhythm and is implicated in the development of jet lags.
Jet Lag. Retrieved on June 5th, 2018.
Why We Get Jet Lags. Retrieved on June 5th, 2018.
How Jet Lag Occurs. Retrieved on June 5th, 2018.
Circadian Rhythm. Retrieved on June 5th, 2018.
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