Circadian Rhythms Flashcards
(25 cards)
Practical application of shift work?
Leads to the desynchronisation of circadian rhymes and can lead to adverse cognitive and psychological effects
What cognitive and physiological effects can shift work have on circadian rhythms?
Memory lapses, poor concentration, issues with fertility, increased risk of cancer, heart disease and diabetes
What happens to night shift workers at 6am?
They suffer with a concentration lapse- increasing the likelihood of accidents
Heart disease- shift workers?
3 times more likely to suffer from heart disease as a result from the stress of adjusting to sleep/wake cycles
Economic implications?
Maintaining worker productivity and preventing accidents in the workplace
Application- pharmacokinetics?
Understanding circadian rhythms can help determine the best time to administer drug treatments
E.g. the risk of heart attack is greatest in early morning- drugs can be taken at night but not released until they will be most effective at dusk
Means there are peak times for administration and dosage of a variety of drugs that treat a range of disorders e.g. cancer, epilepsy, respiratory issues- increases their efficiency
Example of an endogenous pacemakers?
Sleep-wake cycle
What is the SCN?
A tiny bundle of nerve cells located in the hypothalamus in each hemisphere
What does the SCN do?
Maintains circadian rhythms such as the sleep/wake cycle
Where do nerve fibres connected to the eye cross in?
An area called the optic chias
What does the SCN receive information from?
Receives information about light directly from the optic chiasm
What did Patricia De Coursey do in 2000?
Destroyed the SCN connections in 30 chipmunks who were then returned back to their natural habitat and observed for 30 days
Sleep/wake of the chipmunks disappeared- by the end of the study, many had been killed by predators- they were awake and vulnerable to attack when they should have been asleep
Where does the SCN pass the information it receives about length and light to?
The pineal gland
What does the pineal gland do?
increases the production of melatonin during the nights
What is an infradian rhythm?
Cycles that last more than 24 hours- e.g. menstrual cycle
What happens with melatonin during SAD?
More melatonin is secreted during the winter months- results in high levels of depression and low mood
McClintock and Stern (1998)?
29 women with a history of irregular periods
9 of them provided pheromone samples from different cycle stages by wearing cotton pads under their armpits for 8 hours
On day 1, the other 20 women smelled the pads
68% found their menstrual cycle had aligned
Evolutionary advantages of being on your period at the same time?
If all the women in one tribe/clan fall pregnant at the same time, there are lots of people to help with childcare
AO3: McClintock and Stern (1998)? : weakness?
Small sample size
Self report methods
Previous research showed no synchrony (Trevathan)
Research with Dogon tribeswoman in Mali who live in close proximity found no synchrony (Strassman)
In any group of women, there will be synchrony by chance
Strengths of McClintock and Stern?
Longitudinal field study
Changes over time could be tracked
Increases the validity of the findings
Limitations of McClintock and Stern?
Could be compromised by extraneous variables e.g. their dies and nutrition
Exercise regimes- fitter women tend to have me regular cycles
Pollution could interfere with biological processes
Rosen et al- SAD (1990)
Large-scale survey of adults who lived in one of 4 different states in the USA
In New Hampshire, New York, Maryland, Florida- measured prevalence rates of Winter SAD and Summer SAD.
Winter SAD rates were significantly higher the more Northern the state was
What did researchers conclude in Rosen et al experiment?
Concluded that living at a more northern latitude (longer, darker Winter days) is likely to lead to SAD- particularly for older adults
Limitations of Rosen et al expeirment?
Lacks explanatory power- not clear why SAD occurs in Northern states
May be other reasons for SAD e.g. life events
