Disruption Of Biological Rhythms Flashcards
Jet travel and jet lag
Jet lag describes the physiological effects of desynchronised circadian rhythms.
Symptoms: nausea, fatigue, disorientation, insomnia, depression.
It is estimated that the dorsal part of the SCN takes several cycles to adjust to large environmental changes.
Phase delay:
Easier to adjust to as it is the same as staying up later than usual or travelling East to west.
Phase advance:
More difficult as you wake up when you’re in a circadian trough- getting up earlier or travelling west to east.
RECHT ET AL found that U.S. baseball results were better for teams travelling East to west. They won 44%!of their games over a 3 year period compared to 37% wins for teams traveling west to east. The East to west teams suffered less from jet lag than the west to east teams.
Shift work and shift lag
Alertness:
Boivin et al said alertness Decreases when cortisol levels are lower in the middle of the night when core body temp is lowest which is called a circadian trough.
Sleep deprivation:
Is inevitable because sleeping during the day is disrupted by noises and daylight. Tilley and wilkinson said sleep is typically 2 hours less than normal
Effects on health:
Knutssen et al said shift workers are three times more likely to develop heart disease.
AO2
RECHT ET AL: there could have been a significant difference in ability between the teams and those who travelled East to west were better. Many confounding variables could explain this difference such as illness, different players being used and referee bias and so the study could lack internal validity in measuring what it was actually meant to measure. So results may also lack external validity to wider generalisation due to confounding variables.
Shift work and jet lag is unavoidable so research has focused on reducing the harmful effects.
Gold et al found that mon-fluctuating shift patterns worked better than changing shift patterns. Constantly changing shift patterns every few days was found to be more disruptive as opposed to fixed shift patterns as bio rhythms could adjust to one one sleep wake cycle.
Solomon said shift work effects are not just due to the direct effects of disruption of rhythms but it may be due to the lack of sleep associated with going ti bed at unusual times or that they experience social deprivation and family disruption as it’s difficult to meet them. Divorce rates may be as high as 60%.
Melatonin has been put forward as a possible solution to shift work and jet lag. It is the natural hormone that induces sleep. Petrie reviewed 10 studies and found that where melatonin was taken near to bed time it was v effective but taken at the wrong time could delay adaptation.
IDA
Gender bias is a concern as most studies have used males in shift work as the majority of shift workers are males. So results may not generalise to to females due to differences in anatomy and hormones.
If shift work can cause negative effects over the long term it raises the ethical question of whether it should be allowed. Research appears to suggest there could be long term negative consequences for some workers and this raises the question of whether it is ethically right to allow employers force shift work of employees with the possible health implications it can bring.
