724360
Description
Mind Map by chloehathaway, updated more than 1 year ago
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Created by chloehathaway
over 10 years ago
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Disruption of Biological Rhythms- Shift Work
- Shift work
- Causes a break down in the usual coordination
between internal biological clocks and external
cues. This can result in an almost permanent
state of desynchronisation that impairs
concentration and physical performance and
increases stress levels incurring long-term
health risks.
- In non-fluctuating shift
work, the shift in circadian
rhythm remains constant
once the body adapts to it.
Resynchronisation may
take a while but it is
possible. Fluctuating shift
intensify the severity of
circadian rhythm
disturbance.
- Causes a break down in the usual coordination
between internal biological clocks and external
cues. This can result in an almost permanent
state of desynchronisation that impairs
concentration and physical performance and
increases stress levels incurring long-term
health risks.
- Research into shift work
- Czeiler et al 1982 studied shift
workers. They found high ilness rates,
sleep disorders and elevated levels of
stress, suggesting that the workers
internal body clocks were out of sync
with exogenous zeitgebers. The
researchers persuaded management to
move to a phase delay system of
rotating shifts forward in time, to reduce
negative effects. Adjusted 21 instead of
7. 9 months later appeared healthier.
This shows how psychological
research can lead to practical
applications incuring positive
outcomes.
- Hawkings and Armstrong-Escher
1978 studied nurses working night
shifts. Found that thier performance
improved over a week, suggesting
that the circadian rhythm adjusts
gradually. However body temperature
regulation was still out of sync,
suggests body clock takes longer to
adjust.
- Czeiler et al 1982 studied shift
workers. They found high ilness rates,
sleep disorders and elevated levels of
stress, suggesting that the workers
internal body clocks were out of sync
with exogenous zeitgebers. The
researchers persuaded management to
move to a phase delay system of
rotating shifts forward in time, to reduce
negative effects. Adjusted 21 instead of
7. 9 months later appeared healthier.
This shows how psychological
research can lead to practical
applications incuring positive
outcomes.
- Evaluation of SW
- Research suggests that disrupting
biological rhythm affects cognitive
process, emotional functioning and
physical functioning demonstrating
the severity of consequences.
- A lot of research utilises
naturalisitc field studies. These
are high in ecological validity
but incur many confounding
varaibles, making
establishment of causality
problematic.
- Much research on shift work
only involved male participants
which therefore means males
tend to be more invovled in shift
work. However, because the
research is gender biased the
results cannot be generalised
due to the fact the results may
not be representative of
females.
- Other factors- shift work
effects are not just due to the
disruption of biological
rhythms. They may be due to
the lack of sleep associated
with having to go to bed at
unusual times. SW expereince
social disruption as well as
diruption to their biological
rhythms, It is difficult to meet
friends and spend time with
family. Soloman 1993- divorce
rates may be high as 60%
among all night shift workers.
- Indivdual differences- the
effects of circadian
disruption vary between
indivduals. It is possible that
those people whose
circadian rhythms change
least are the ones who cope
best overall. Reinberg et al
1984 found that people who
gave up shift work because
they could not cope tended
to have rhythms that
changed a lot while on shift
while the 'happy shift
workers' had unchanging
rhythms.
- Evaluation resetting biological clocks- Bovin et al 1996
investigated the power of artificial light in resetting our
biological clocks. 31 male subjects were divided into
four groups and put onto a inverted sleep-wake cycle
for three days (kept awake at night and allowed to
sleep during the day). Each 'day' when they woke they
were exposed to five hours of very dim light, followed
by 1 of 4 conditions.: Group 1 were exposed to very
bright light, group 2 to bright light, group 3 had ordinary
room light and group 4 reamined in dim light. Core
body temperature was used to assess each persons
current circadian rhythm. After three days, members of
group 1 had advanced five hours earlier; group 2 had
advanced three hours; group 3 had advanced by 1
hour; and group 4 had drifted one hour later in their
circadian rhythms. This shows that even room lighting
can have an effect on the circadian rhythm and very
bright light has a significant effect.
- Lab experiments- the strength of lab experiments such as Boivin et al is that
extraneous variables can be carefully controlled to isolate causal variables. However,
there is a question over whether the same 'laws' will apply in everyday life. It is therefore
important to conduct field experiments as well to confirm the findings. Boivin and James
2002 used intermittent bright lights in a field study of nurses which confirmed the
effectiveness of bright lighting to promote circadian adaption.
- Lab experiments- the strength of lab experiments such as Boivin et al is that
extraneous variables can be carefully controlled to isolate causal variables. However,
there is a question over whether the same 'laws' will apply in everyday life. It is therefore
important to conduct field experiments as well to confirm the findings. Boivin and James
2002 used intermittent bright lights in a field study of nurses which confirmed the
effectiveness of bright lighting to promote circadian adaption.
- Evaluation resetting biological clocks- Bovin et al 1996
investigated the power of artificial light in resetting our
biological clocks. 31 male subjects were divided into
four groups and put onto a inverted sleep-wake cycle
for three days (kept awake at night and allowed to
sleep during the day). Each 'day' when they woke they
were exposed to five hours of very dim light, followed
by 1 of 4 conditions.: Group 1 were exposed to very
bright light, group 2 to bright light, group 3 had ordinary
room light and group 4 reamined in dim light. Core
body temperature was used to assess each persons
current circadian rhythm. After three days, members of
group 1 had advanced five hours earlier; group 2 had
advanced three hours; group 3 had advanced by 1
hour; and group 4 had drifted one hour later in their
circadian rhythms. This shows that even room lighting
can have an effect on the circadian rhythm and very
bright light has a significant effect.
- Research suggests that disrupting
biological rhythm affects cognitive
process, emotional functioning and
physical functioning demonstrating
the severity of consequences.
- Real world application
- Serious incidents like the Three Mile
Nuclear Plant accident of 1979 and the
Chernobyl reactor meltdown of 1986
occured due to concentration and decision
failures in the early hours of the morning.
This suggests that the desynchronisation
effects of working at irregular hours impairs
performance with potentially disastrous
consequences.
- Serious incidents like the Three Mile
Nuclear Plant accident of 1979 and the
Chernobyl reactor meltdown of 1986
occured due to concentration and decision
failures in the early hours of the morning.
This suggests that the desynchronisation
effects of working at irregular hours impairs
performance with potentially disastrous
consequences.
- Sleep deprivation- workers who
have to sleep by day often
expereince sleep problems
because when they finish work its
daytime and there are other
interpruptions and daylight
reduces sleep quality. Daytime
sleep is usually between 1-2
hours less sleep; REM is affected
(Tilley and Wilkinson 1982). Poor
quality daytime sleep then makes
it even more difficult for shift
workers to stay awake through
the night, especially when they hit
the circadian 'trough'
- Decreased alertness-
Nightworkers often
expereince a circadian
disruption of decreased
alertness during thier
shifts (Boivin et al 1996).
This occurs between
midnight when cortisol
levels are the lowest, and
4am when core body
temperature is at its
lowest.
- Effects on health- there is a
significant relaltionship between
shift work and organ disease.
Knutsson et al 1986 found that
indivduals who worked shifts for
more than 15 years were 3
times more likely to develop
heart disease than non-shift
workers. Martino et al 2008
linked shift work to a range of
organ diseases, including
kidney disease. This may be
due to the direct effects of
desynchronisation or indirect
effects such as sleep disruption.
- Effects on health- there is a
significant relaltionship between
shift work and organ disease.
Knutsson et al 1986 found that
indivduals who worked shifts for
more than 15 years were 3
times more likely to develop
heart disease than non-shift
workers. Martino et al 2008
linked shift work to a range of
organ diseases, including
kidney disease. This may be
due to the direct effects of
desynchronisation or indirect
effects such as sleep disruption.
- Decreased alertness-
Nightworkers often
expereince a circadian
disruption of decreased
alertness during thier
shifts (Boivin et al 1996).
This occurs between
midnight when cortisol
levels are the lowest, and
4am when core body
temperature is at its
lowest.
- Reducing the harmful effects
- Rotating shifts- research
indicates that most problems
occur when people have to
do rotating shifts, where
shifts alternate every few
days (Gold et al 1992).
Non-fluctuating shifts are
less disruptive because they
can get used to the
sleep-wake cycle. Although
days off are likely to mean
temp changes in sleeping
patterns which will disrupt
the biological rhythms.
- Forward-rotating shifts-
follow the logical order of
the day (phase delay) and
may be easier on the body
and less damaging to
health (according to a
review by Bambra et al
2008). E.g. shift in the
morning for one week, a
shift in the afternoon for
another week and finally a
night shift in the third
week.Bambra also
concluded that rotating
workers through shift
changes more quckly
(every 3-4 days instead of 1
week) is better for health
and work-life balance
- Rotating shifts- research
indicates that most problems
occur when people have to
do rotating shifts, where
shifts alternate every few
days (Gold et al 1992).
Non-fluctuating shifts are
less disruptive because they
can get used to the
sleep-wake cycle. Although
days off are likely to mean
temp changes in sleeping
patterns which will disrupt
the biological rhythms.
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