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Disruption to Biological Rhythms

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Exam Question: Discuss the disruption of biological rhythms (8+ 16 Marks)
Biological rhythms are controlled by endogenous pacemakers (Oscillators). endogenous pacemakers can easily be changed by exogenous Zeitgebers such daylight. However if the oscillators are more resistant this can lead to desynchronisation. The most common type of disruption to biological rhythms are shift work and Jet lag.
Shift work described a type of job in which individuals have to be alert at night when they work, and they sleep during the day. This results in reduced quality of sleep because it goes against our natural biological rhythms as daytime sleep can be interrupted due to exogenous zeitgebers such as light and outside noise. One of the effects of shift lag has been found to be decreased alertness. Shift workers often experience a circadian trough where there alert levels plummet. This usually occurs between 12.00am and 4.00am and is due to reduced body temperature and a decrease in cortisol levels. This predicted effect of shift work has been supported by research by Moor Ede. It has been found that the decreased alertness as a result of shift lag costs the USA $70 billion per year. More evidence comes from the 3 Mile Island nuclear power station disaster, which occurred at around 4am, and similarly the Exon Val Dez oil tanker accident occurred at 12am and resulted in the spillage of oil in the oceans affecting thousands of wildlife.
A second effect of shift work is believed to be the increased risk of organ disease that is associated with the number of years spent doing shift work. Knutsson et al provided supporting evidence for this, as it was found that those who spent 15 years or more doing shift work had an increased risk of developing heart disease.

Another effect of shift work is sleep deprivation. It has been suggested that sleeping during the day is less effective

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