Discuss the consequences of disrupting biological rhythms [16 marks]

AO1

• effect of jet lag

  • loss of appetite, fatigue, insomnia, nausea

  • more pronounced effect when travelling east due to ‘phase advance’ harder to overcome

• effect of shift work, desynchronisation, going against exogenous zeitgebers of light and social cues, endogenous pacemaker of SCN causing high melatonin levels during the night, affected circadian rhythm

  • Boivin et al (1996), workers experience a circadian trough at 6am, period of reduced concentration, makes accidents more likely

  • Knutsson (2003), shift work causes high stress (in adjusting to new sleep-wake patterns) and poor quality sleep, resulting in three times greater likelihood of developing cardiovascular (heart) disease

AO3

• application of understanding

  • switch shifts at 6am to reduce the possibility of fatal mistakes

• correlational evidence on health impacts of shift work, shift work commonly occupied by people with low-socioeconomic status, presence of social gradients (e.g. obesity due to diet-related factors), more likely to have health issues regardless of shift work, cannot claim the health impacts are definitely caused by disrupted circadian rhythm

• similarly, the detrimental impacts may be due to psychological strains, not biological - Solomon (1993) pointed out the strain of missing family on explaining high divorce rates in shift workers

• poor functioning of jet lag due to changed circadian rhythms and melatonin production, may instead be due to travel stress, caffeine, low-oxygen cabins, lack of movement while travelling etc. so only including biology as an explanation is reductionist, jet lag is multifactorial.

• evidence for effects of East/West differences in jet lag from Recht et al, basketball team more likely to win matches when travelling West for games