Disrupting Biological Rhythms

Nature of sleep
1. Shift work
  1. Consequences of shift work: tiredness, irritable, cardiovascular disease, cancer (Norway - night shift workers sued, breast cancer)
  2. Night shifts - Harder to get as much sleep e.g. light, noise and family commitments
  3. Tiley and Wilkinson (1982) show that daytime sleep is between one and two hours shorter than nocturnal sleep period and our REM is particularly affected. This therefore shows that it makes it even more problematic for shift workers to stay alert. This shows the biological approach, which includes both physiological and evolutionary explanations. - physiological approach is seen as deterministic, not capable of free will.
  4. Knutsson et el (1986) - Individuals who worked shifts for more than 15 years were three times more likely to develop heart disease than non-shift workers. This is supported by Martino (2008) where he linked shift work to many different organ diseases, particularly kidney disease. This research is relevant and recent, suggesting that the shift work in today's society is still harmful to our organs.
2. Jet Lag
  1. Physical symptoms - Fatigue, difficulty concentrating, insomnia, diarrhea, dehydration, constipation, nausea, sweating, dizziness
  2. Tips for reducing symptoms - stay hydrated, avoid alcohol inflight, don't sleep too early, sleep on plane, a just internal clock before
  3. Recht et al (1995) - effects of jet lag on baseball. Studied 3 complete season records (1991-93) of 19 North Americans, Eastern or Pacific time zone based baseball teams. To play each other these teams would have to travel over 3 time time zones. They found that home teams won 56% of the games, but the chances of winning depended on whether the visiting team had traveled eastward. When this was the case, home teams could also expect to score1.24 more runs than the visitors. Jet lag is generally more severe traveling west to east. - problems with the selection of data for analysis. Lack of control over the behavior of team members en route which may effect performance.
  4. Rafasson et al (2001) - Evidence suggests that chronic jet lag can contribute significantly to the development of cancer. Using data gathered from 1,500 female flight attendants, they found that those who had been flying for over 5 years had double the risk of breast cancer. - Could be down to other effects e.g. dehydration, magnetic fields, cosmic radiation. Didn't take into account family differences such as history of cancer.
Explanations of sleep
1. Restoration
  1. A02- Horne (1988) distinguished between core (stage 4 & REM) and optional (stages 1 to 3) sleep and claimed that only core sleep was critical for restoration for the brain as restoration of the body can occur during resting wakefulness.
  2. A02 - Objective measurement - the physiological measures of sleep, e.g. REM activity and levels of neurochemicals, are objective, which means that they are less subject to bias.
  3. A01- Purpose of sleep is to repair and recharge the brain and body.
  4. A02 - Multi-perspective - the sleep deprivation research suggests that effects are more psychological than physiological (Huber-Weidman, 1976 and the Peter Tripp case study) and so the main function of sleep may be to recover psychological functioning.
  5. A02- Androcentricity -all of the sleep deprivation research is based on male participants.
  6. A02-Animal research - can you apply findings from Rechstaffen's rats or Jouvet's cats to human behaviour?
  7. A02 - Case studies - the studies of sleep deprivation in humans are mainly case studies or small samples - difficult to extrapolate from (Randy Gardner)
  8. A02 - Oswald (1980) claimed that NREM sleep restored the body and REM sleep restored the brain
  9. A02- Stern and Morgane (1974) REM sleep allows the brain to replenish neurotransmitters
  10. A02 - Hartmann (1973) REM sleep is a time for synthesising noradrenaline and dopamine.
2. Evolutionary
  1. A01 - Species that sleep have survived to reproduce & carry sleep into the next generation as an adaptive behaviour - if it was non-adaptive, i.e. does not have an evolutionary purpose, then it should have disappeared.
  2. A02- Low adaptive value - In some species if sleep were simply adaptive then it should have been selected out.
  3. A02- Lacks scientific validity - Evolutionary theories are post hoc, i.e. they have been proposed in retrospect and consequently lack empirical support, and so they lack scientific validity. DIfficult to dismiss and so they are neither verifiable nor falsifiable.
  4. A02- Meddis (1975) suggested that sleep is adaptive because the immobility of sleep keeps animals safe from predators and that it occurs when normal activities (such as feeding) are impossible.
  5. A02 - Webb (1982) proposed the hibernation theory that suggested the adaptive function of sleep is energy conservation.
  6. Genome lag - may have been more relevant in our evolutionary past. However, such explanations may not be true of human sleep today as predators no longer pose such as threat. It may well be that sleep patterns will change in time as evolution is a gradual process and so the patterns we have at the moment may be due to genome lag, which occurs because the environment changes much more quickly than the genes.
  7. A02 - Deterministic & reductionist - Evolutionary theories are deterministic as they ignore free will. People can and do choose when they want to sleep. Sleep is far more complex a process to have evolved solely as protection as this does not explain why we have the different stages and cycles of sleep or why we need to catch up on some of our missed sleep. Evolutionary theories ignore the physiological and psychological functions of sleep and so are unlikely to provide a full explanation for sleep.
3. Neural explanations
  1. A01 - Hypocretin - this chemical is part of cerebrospinal fluid (CSF) and is also known as orexin. There is a link between narcoleptic sufferers and reduced levels of this chemical. Scammel et al and Arii et al both suggest narcolepsy is caused by a loss of cells in the hypothalamus that secret Hcrt. A direct link between the hypothalamus and narcolepsy has been found from research conducted on non-human animals.
  2. Arii et al (2001) Report a case study of a 16 year olf girl who underwent brain surgery for the removal of a tumour from the region of her hypothalamus. Although she had no history of sleep problems prior to the surgery, afterwards she experienced intense urges to sleep during the day time, and often fell asleep during monotonous tasks and whilst watching tv. CSF extracted from her spine was compared with CFS obtained from control patients undergoing assessment for other problems. It was found that CSF contained reduced levels of HCRT. MRI scans indicated that surgery to remove the tumour had caused damage to her hypothalamus. Arri et al sugest that HCRT neurotransmission has been distributed by damage to the HCRT producing cells in the hypothalamus.
  3. Thannickal et al (2007) The role of HCRT has been supported by research studies of people with Parkinson's disease, a degenerative brain disorder which involves loss of cells in many brain areas. People with Parkinson's show sleep complaints that are the same as Narcoleptics. A post modern examination of the brains of people with Parkinson's found that the brains had lost up to 62% of the cells that contain HCRT. This is further supported by other research which has shown reduced levels of HCRT in CSF taken from the ventricles of people with Parkinson's disease.
  4. REDUCIONIST
4. Genetic explantions
  1. In the 1970s a clear genetic explanation for narcolepsy was discovered, it was found that certain breeds of dogs appeared to have inherited narcolepsy. A colony of narcoleptic dogs was then bred to aid with research in an effort to locate the gene. Nishino et al (1997) found that narcoleptic Doberman Pinchers have a genetic mutation affecting Hcrt. Unfortunately this defect has not been found in humans so the research was obsolete. ETHICAL ISSUES
  2. A02 - It appears to be the exception rather than the rule that narcolepsy runs in families, most narcoleptics do NOT have a relative with the disorder. Mignot et al (1998) carried out twins study research looking for this link. 16 sets of identical twins were investigated where at least one twin had narcolepsy, in only 4 of these pairs did both have the condition. In all likelihood the cause of narcolepsy is probably a combination of genetic susceptibility and one or more environmental triggers, such as hormonal changes, infection, trauma or immune system functioning have the condition.

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Disrupting Biological Rhythms

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	Criado por rowanechapman aproximadamente 8 anos atrás