Infradian Rhytms

Question 2

Infradian rhythms A01

Answer 2

Rhythms that have a duration greater than 24hr, e.g the female menstrual cycle
Menstrual cycle lasts about one month and there are considerable variations in the duration of these cycles
This is regulated by hormones either promoting ovulation or stimulate the uterus for fertilisation
Ovulation occurs halfway though the cycle were oestrogen levels peak, after the downfall of this progesterone takes over and rises
Annual rhythms may relate to the seasons for example migration might depend on the temperature fluctuations
Research suggests a seasonal change in mood, people become severely depressed in winter months
Winter is also assosiiated with an increase in heart attacks

Question 3

Limitation- alternatives can affect infrandian rhythms

Answer 3

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▪️P Research suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers (external factors)
▪️E Reinberg (1967) examined a woman who spent three months in a cave with only a small lamp to provide light - Reinberg noted that her menstrual cycle shortened from the usual 28 days to 25.7 days
▪️L This result suggests that the lack of light (an exogenous zeitgeber) in the cave affected her menstrual cycle, and therefore this demonstrates the effect of external factors on infradian rhythms

Question 4

Alternative holistic approach A03

Answer 4

■ P There is further evidence to suggest that exogenous zeitgebers can affect infradian rhythms. ■ E Russell et al. (1980) found that female menstrual cycles became synchronised with other females through odour exposure. In one study, sweat samples from one group of women were rubbed onto the upper lip of another group. Despite the fact that the two groups were separate, their menstrual cycles synchronised. This suggests that the synchronisation of menstrual cycles can be affected by pheromones, which have an effect on people nearby rather than on the person producing them.
Indicates external factors need to be considered

Question 6

Research strength evolution value

Answer 6

P Evolutionary psychologists claim that the synchronised menstrual cycle provides an evolutionary advantage for groups of women
■ E as the synchronisation of pregnancies means that childcare can be shared among multiple mothers who have children at the same time, newborns can be cared for collectively
■ L so increases chances of survival

However, competition; too many cycling together, competition for highest quality males and thereby lowering fitness, Jeffrey Schank - avoidance of synchrony best adaptive evolutionary strategy

Question 7

Weakness of research A03

Answer 7

weakness - methodological issues in synchronization studies

■ P Methodological issues in synchronization studies
■ E Confounding variables in studies such as stress and exercise
■ L Weakens any support for exogenous zeitgebers and the menstrual cycle