Outline the consequences of disruption to bodily rhythms (6)

Disruption can occur when there are major discrepancies between the activity of endogenous pacemakers and zeitgebers in external world, such as maybe occur in shift work where people may be expected to work when their body clock is expecting the person to be asleep or in jetlag whereby the body is set to the time zone of the home country while light and social cues are set to local time. This can lead to a wide range of physical symptoms including nausea, headaches, extreme daytime drowsiness, finding it very hard to fall asleep at bedtime, loss of appetite and gastro-intestinal problems including indigestion, sweaty palms and clamminess. Research has also shown that shift workers are three times more likely to die of heart attacks, (Knutsson, 1982). One crucial problem affecting shift workers is that due to disruption to their circadian rhythms they find it hard to fall asleep and research suggests that shift workers sleep at least one hour less than matched controls.

Psychological symptoms include moodiness, irritability, decreased alertness, poor concentration and impaired cognitive functioning, e.g. poor memory. Physical and psychological symptoms together in addition to less time spent with family and friends may cause strain on social relationships, decreasing access to social support and increasing stress levels even further. This problem mean that people might not function as effectively at work, decreasing productivity and leading to decreased job satisfaction. Also these problems have been linked to human errors which have caused many accidents on the road and at work including several national environmental disasters such as the Exxon Valdez oil spill and leaks at nuclear and chemical plants such as Three Mile Island, Bhopal and Chernobyl, which affects thousands of people to this day.

Describe research into the consequences of disruption to bodily rhythms (6)

Kleitman noted that the time taken to adjust to air travel is about one day per time zone crossed and that travelling from east to west creates less severe symptoms, which do not require such a long period of adjustment. Recht (1995) conducted natural experiment looking at the number of wins obtained at a baseball tournament in America. They compared the performance of home teams with those who had flown to the destination crossing time zones and travelling either east to west or west to east. It was found that those team who had not disrupted their body rhythms by crossing time zones won their games 46% of the time, whereas team which had travelled east to west won 44% of the time and those teams who had travelled from the west to east won only 37% of the time. It has been noted by Takahashi that melatonin tablets can be effective in helping to resynchronise bodily rhythms more quickly following a 11 hour flight. Stokkan found that people who ate meals at local times rather than when they were hungry whilst jetlagged adapted more quickly.

With regard to shift work , Knutsson showed that those who had done shift work for 15 years were three time more likely to die of a heart attack. On a positive note, Charles Czeisler conducted a field experiment at a Utah chemical plant where workers were experiencing difficulties with shiftlag. He persuaded the manager to change the shift pattern from weekly rotating shifts that followed a phase advance pattern rolling backwards, (Night, Evening, Day) to a three weekly rotating phase delay pattern rolling forwards (Day, Evening, Night). Workers reported that their symptoms were alleviated, they slept longer during the day, social relationships improved as did workplace

productivity and job satisfaction. Leading on from this he also found that by supplying workers with black out blinds for their bedrooms and installing bright strip lighting in the factory, he could enabled the workers to entrain their sleep wake and temperature cycles within just six days. With the use of very bright light he also went onto find that rhythms could be entrained in only 3 days!

Assess the consequences of disrupting bodily rhythms (12)

Shift-work presents an opportunity to work anti-social hours and for some people the extra income that this may provide can be very attractive and necessary in many cases. People may think that the work will give them more time to spend with their families, allowing them for example to look after children during the day and earn while they are a sleep and their partner is at home. So is shift work really that harmful? Likewise many people have to take regular international flights for their work, not least long haul pilots and cabin crew! Should they worry about the longer term effects of constant jetlag? Should managers bother to pay extra to allow their performers or athletes time to adjust to local time before important events abroad or is decreased performance a myth?

There are a number of research studies which suggest that some people could suffer serious health problems which are linked to shift work. Knutsson for example showed that shift workers are three times as likely to die of heart attacks if they have been employed in this type of work for 15 years or more. This could be explained by the fact that their bodies may be suffering the ill effects of stress rather than shift work per se, since cardiovascular disease has also been associated with workplace stressors. It is possible that if shift workers work hard to eliminate stress from their lives they could escape these ill effects which are also related to low job control (Marmot ) which may also be apparent in job such as production workers who work night shifts. Since the study is correlational and no effort is made to control confounding variable, caution must be taken in interpreting the findings. However, shift workers may wish to bear this in mind and try to build in exercise, healthy eating and stress management and try to avoid cigarettes and alcohol. to reduce the risks.

Another study which suggests that concern about the consequences of disruption to bodily rhythms is not without justification, was conducted by Recht (1995) who noted that performance at a baseball tournament was significantly worse for those team who had crossed time zones to get there, and specifically for those who had travelled West to East who only won 37% of their games compared with 44% for team travelling east to west and 46% for those not travelling at all. This poorer performance could have been caused by the fact the players had higher body temperature during the day than expected causing drowsiness or that physiological arousal levels were low, in geenrla terms their body may have been preparing them for sleep when they needed to be at their peak performance. Cognitive deficits may have made them less accurate in determining how to react and predicting what other players were doing. They may also have slept badly the night before due to not being able to get to sleep at the required time meaning they were more tired than usual. However this was a natural experiment and as such internal validity is lowered since players were not randomly assigned to the conditions of east/west travel, west/east travel and no travel. It could have been that the teams from the West were simply not such good players or that other factors had affected their performance that day other than jetlag such as the amount fo alcohol consumed on the plane, poor sleep the night before due to nerves or excitement.

Although it appears that the effects of jet lag and shift work may be real enough, research also supports that there are some remedies which could alleviate the negative effects. For example, Czeisler demonstrated that job satisfaction and productivity could be increased and symptoms and sick days decreased by altering the shift work pattern from a weekly phase advance pattern where shifts rolled backwards from night to evening to day compared with a new system where shifts changed every three weeks and rolled forwards day, to evening to night, giving the body more time to adjust and mimicking the naturally longer sleep/wake cycle observed in studies such as those carried out by Siffre (1975) and Aschoff and Wever. This was an excellent study as the fact that it was a field experiment mean t that external validity was high and the findings had excellent applications which can help companies across the world. However such changes may not always be necessary as other research by Czeisler has also shown that bodily rhythms can also be altered more rapidly by providing black out blinds to help people sleep better during the day and strip lighting in the factory to inhibit melatonin production at night. He has shown that this can help rhythms to adjust within 6 days. Better still he showed that exposure to phototherapy as in the treatment of SAD can adjust rhythms within just three days. This demonstrates that the effects of shift work and jet lag can easily be overcome with some simple and cost-effective changes.

It should also be noted that ideas that shift work and jet lag cause negative effects of health and functioning is overly determinist and does not take into account individual difference. For example, some people may manage such situation with minimal effects and thus not everyone should be put off as they may find that they are unaffected. Reinberg found that some people with circadian rhythms that were particularly slow to change in accordance to zeitgebers were in fact unlikely to suffer ill effects. Also males and females may be differentially affected since research suggests that males have more reactive nervous systems generally and this could mean that the additional arousal which seems to sometimes be the source of some of the problems may affect men more than women.

Also it should be noted that some of the ill effects supposedly caused by disrupted body rhythms may in fatc be a consequence of sleep deprivation or other factors such as reduced access to social support, when partners work art different times and don’t see each other as much. It would be interesting to compare couples where both partners work the same shift and partners which work different shifts to see how their health might be differentially affected.

In conclusion, one can see that research in this area has far reaching applications which can help to improve the lives of many people and has shown that while disrupting bodily rhythms s can be problematic there are positive solutions which can help people to conduct the lifestyles that suit them best.