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Consequences of Disrupting Biological Rhythms Essay Plan
1. Describe in detail shift work and shift lag. Boivin found that night workers often experience a
Circadian "trough" of decreased alertness during their shifts, this is between midnight, when
Cortisol levels are lowest and 4am when core body temperature is at its lowest. Tilley and
Wilson- daytime sleep is typically between one and two hours shorter than a nocturnal sleep
period, and REM is particularly affected. Knutsson found individuals who worked shifts for
more than 15 years were three times more likely to develop heart disease than non-shift
workers. This could be because of direct effects of desynchronisation or indirect effects such
as sleep disruption.
2. Outline briefly jet travel and jet lag. Recht- looked at US baseball results over a three year
period. Teams that travelled from east to west won 44% of their games, unlike when
travelling from west to east who only won 37%. The conclusion he drew from why this
occurred is because east to west is phase delay so they wake up later then they are used to.
Whereas, travelling from west to east is phase advance so they have to wake up and earlier
then they are used to.
3. Critical Point 1: The effects described about disrupting biological rhythms have strong
evidence. For instance Gold found that more problems happen where shifts alternate every
few days. However, by finding out these results you can use it to improve shift work by
making sure people do the same shift for a week before changing to a different time.
Therefore, this research gives positive implications.
4. Critical Point 2: Most of the studies carried out are lab experiments so there is the issue of
demand characteristics and whether the same results would apply in real life situations.
Boivin and James used intermittent bright light in a field study of nurses, which confirmed the
effectiveness of bright lighting to promote circadian rhythms. Therefore, this evidence
shows that what was found in the lab experiments was true so it can be applied to real life
5. Critical Point 3: There is another positive application for discovering about shift work and
shift lag. Herxheimer and Petrie looked at 10 studies and found that where melatonin was
taken near to bedtime it was remarkably effective. Consequently demonstrating that these
effects do exist but they are treatable. However, there are individual differences to take
into account when generalising results from different people, as well as volunteer bias in the
6. Critical Point 4: Also, there are other ways to reduce the effects of shift work and jet lag.
Fuller found that a period of fasting followed by eating on the new time schedule should help
entrain biological rhythms. This is likely to be because some of our body clocks are reset by
food intake. As a result of this, the results found from this research can be applied to real life
making this research reliable and useful.
7. Critical Point 5: Finally, the other positive application for finding out about how shift work can
disrupt biological rhythms is the introduction of forward-rotating shifts. Bambra claimed that
they should follow the logical order of the day (phase delay). Therefore, they will be easier
on the body and less damaging to worker health. As well as, rotating workers through shift
changes more quickly, for instance every few days instead of weekly, is better for health
and work-life balance.