The ins and outs of jet lag

What is jet lag?

Anybody who has done long air travel across a few time zones has no doubt experienced jet lag. The dictionary definition of jet lag is, ‘a temporary disruption of the body’s normal biological rhythms after high-speed air travel through several time zones.’ In other words, when you arrive at your destination you may have experienced some or all of the following symptoms: disturbed sleep, fatigue at unusual hours (during the daytime), decreased ability to perform mental and physical tasks, or reduction in cognitive alertness – symptoms which normally last a few days.

Our body has a natural ‘biological clock’ that works on a 24-hour cycle called circadian rhythms. According to the National Sleep Foundation (NSF), ‘these rhythms are measured by the distinct rise and fall of body temperature, plasma levels of certain hormones and other biological conditions.’ Sunlight plays a huge role on our circadian rhythm, i.e. when we wake up and go to sleep.

Why is jet lag worse after flying east?

The time it takes for you to adjust to the new time zone will be dependent on the number of time zones you have crossed and the direction you have flown – east to west or west to east. A study done by researchers at the University of Maryland used complex mathematical models to find that the average person’s circadian rhythm slightly exceeds 24 hours by approximately 30 minutes (24.5hrs). At first glance it might not seem like much, but this small amount is significant enough to help explain the west to east asymmetry for jet lag recovery (i.e. worse jet lag traveling west to east) and can equate to days needed to recover when crossing several changing time zones.

The National Sleep Foundation (NSF) recommends a number of treatments to minimise the effects of jet lag so I suggest, if you are travelling, to check out their website. When I travelled, the things I found most useful to reduce the effects of jet lag were to make sure I had ample sunlight exposure during the day, to catch a flight that landed early evening so I could go to bed at a reasonable local time shortly after arriving to avoid having to stay up all day, and to avoid caffeine 4-6 hours before bedtime.

Hope this helps! Good night – gute nacht – bueñas noches – bonne nuit – buona notte.

By Janine Jungfels – Pushys Sponsored Athlete

[1] Choy, M., & Salbu, R. L. (2011). Jet Lag: Current and Potential Therapies. Pharmacy and Therapeutics, 36(4), 221–231.
[2] Lu, Z., Klein-Cardeña, K., Lee, S., Antonsen, T.M., Girvan, M., & Ott, E. (2016). Resynchronization of circadian oscillators and the east-west asymmetry of jet-lag. Chaos: An Interdisciplinary Journal of Nonlinear Science, 26(9), 094811.
[3] National Sleep Foundation 2018, Jet Lag and Sleep (online), Available: https://sleepfoundation.org/sleep-topics/jet-lag-and-sleep (2 March 2018).

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