Consequences of shift work: tiredness,
irritable, cardiovascular disease, cancer
(Norway - night shift workers sued, breast
cancer)
Night shifts - Harder to get
as much sleep e.g. light,
noise and family
commitments
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.
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.
Tips for reducing symptoms - stay hydrated,
avoid alcohol inflight, don't sleep too early,
sleep on plane, a just internal clock before
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.
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
Restoration
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.
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.
A01- Purpose of sleep is to repair and recharge the brain and body.
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.
A02- Androcentricity -all
of the sleep deprivation
research is based on male
participants.
A02-Animal research - can you apply
findings from Rechstaffen's rats or
Jouvet's cats to human behaviour?
A02 - Case studies - the studies of sleep
deprivation in humans are mainly case
studies or small samples - difficult to
extrapolate from (Randy Gardner)
A02 - Oswald (1980) claimed that NREM
sleep restored the body and REM sleep
restored the brain
A02- Stern and Morgane (1974) REM sleep
allows the brain to replenish
neurotransmitters
A02 - Hartmann (1973) REM sleep is a time for
synthesising noradrenaline and dopamine.
Evolutionary
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.
A02- Low adaptive value - In
some species if sleep were
simply adaptive then it should
have been selected out.
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.
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.
A02 - Webb (1982) proposed the
hibernation theory that suggested
the adaptive function of sleep is
energy conservation.
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.
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.
Neural explanations
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.
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.
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.
REDUCIONIST
Genetic explantions
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
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.