Disruption of biological rhythms

Jet lag occurs when the individual crosses time zones.

This disrupts the circadian and ultradian rythms.

Jet lag only occurs when there is a significant difference between your endogenous pacemker and the local exogenous zeitgebers (E.g Clocks/daylight.)

This disruption can lead to pysiological symptoms e.g fatigue, headaches and irritability.

Other bodily rythms can also be affected e.g body temperature- adding to the feeling of disorientation.

Most travellers find:

It is harder to adjust when travelling from West to East as our day is shortened- phase advance.

It is easier to adjust when travelling East to West as our day is lengthened- phase delay. This is easier as we know it is easier to stay up late than get up early.

Research evidence

Klein- found that passenger travelling East to West took only 1 day to adjust

whereas passengers travelling West to East took 6 days on average to adjust.

Results were independent of whether people were travelling back to or away from home.

Suggests poeple find it harder to adjust to phase advance than phase delay.

Futher evidence

Recht- studied results of US baseball teams over 3 Years

Teams travelling East to West won 44% of their games.

Teams travelling West to East won only 37% of games.

One criticism of this research is that the teams in the East may just simply have been better than those in the West.

However this variable should of evened itself out over 3 Years.

Determinism

Suggests travellers cannot control their own sleeping behaviour as they are controlled by endogenous mechanisms.

However people can overide their endogenous mechanisms by forcing themselves to adopt social rhythms (local zeitgebers) and by sleeping and eating at the time of their destination.

For example reasearch suggests that fasting followed by eating at the times of the destination can entrain our biological rhythms.

Possibly because our body clock is reset by food intake.

This demonstrates an impressive ability to exercise free will in order to alter our biological rhythms to adapt to new environments.

Practical application

Research findings regarding circadian rhythms can be used to combat the effects of disruption.

There is evidence that suggests that melatonin can speed up the resychronisation process and reduce jet lag.

Beaumont found taking melatonin at bedtime will significantly reduce the effects of jet lag.

As we gain a deeper knowledge of the endogenous pacemakers and exogenous zeitgebers we can better understand how these consequences occur.

Therefore we can develop effective ways to combat them.

This suggests that taking melatonin is a practical application of the research into circadian rhythms.