updated 27 January 2019
Jet Lag occurs when our circadian rhythms become out of phase with our local time.
- regulate levels of hormones that influence our energy and sleep-awake cycles
- induce us to slow down or stop an activity
- induce the (virtual) feeling of tiredness so that we plan for the update-repair functions of sleep
- cause us to plan to be at home, in a “cave” where we are safe to sleep / hibernate and when other species also resting. (Interestingly, dominant aggressors hunt at night, though this puts them under threat in daylight from other animals. Thus, these packs share lookout in daytime.)
Our circadian rhythms are steered by cortisol levels that ebb and flow in our body. Cortisol levels vary naturally over a 24 hour cycle, affecting:
- signals every cell when to use energy, when to rest, when to repair/replicate DNA.
- body temperature,
- blood pressure,
- physical activity and
When we change time zones, it’s the out-of-sync cortisol levels that induces these “jet lag” effects. Prolonged disruption to our circadian rhythms can contribute to ailments such as diabetes, heart disease, neurodegenerative diseases and depression.
Our circadian rhythms are synchronised with our “body clock”.
- Many “chronotypes” contribute to our overall perception of time (body clock)
- The most accurate proxy for our body clock is the level of serotonin in our blood (accurate to 1/2 hour)
- Our body clock slowly slews to update with changing daylight. So when we travel to a new time zone, it takes many days for our body clock (and circadian rhythms) to slew to our new daylight times. Allow about one day per one hour of time zone change to fully sync to the new time zone and recover from the effects of Jet Lag.
Advanced travellers, who wish to reduce the effects of jet lag can slew their circadian rhythms (“body clock”) towards the new time zone by:
- synchronising with the time zone of the final destination – as soon as you board the aircraft.
- exposing yourself to light or
- melatonin supplements (sleep hormone) Dr Karl Kruszelnicki will soon contribute to this page, his views about how to use melatonin to control and limit the effects of circadian dysrhythmia (jet lag).
Adam MacDougall interviewed me regarding Jet Lag and how to minimise its effects. This interview has proven very popular.
Coral and I wish you a happy New Year and the best for 2019.
For more information:
- Scientific American, February 15 p 43
- Scientific American, January 2019 p9