infradian rytms

Question 1

Infradian rhythms definition

Answer 1

Rhythms that have a duration of over 24 hours, and may be weekly, monthly or annually

Question 2

Example of a monthly infradian rhythms

Answer 2

Menstrual cycle

Question 3

The menstrual cycle

Answer 3

Regulated by hormones that either promote ovulation or stimulate the uterus for fertilisation.

Ovulation occurs roughly halfway through the cycle when oestrogen levels are at their highest, and usually lasts for 16-32 hours.

After the ovulatory phase, progesterone levels increase in preparation for the possible implantation of an embryo in the uterus.

It is also important to note that although the usual menstrual cycle is around 28 days, there is considerable variation, with some women experiencing a short cycle of 23 days and others experiencing longer cycles of up to 36 days

Question 4

Example of annual infradian rhythm

Answer 4

Seasonal affective disorder

Question 5

Seasonal affective disorder

Answer 5

Related to the seasons.
Research has found seasonal variation in mood, where some people become depressed in the winter, which is known as seasonal affective disorder (SAD).

SAD is an infradian rhythm that is governed by a yearly cycle.

Psychologists claim that melatonin, which is secreted by the pineal gland during the night, is partly responsible. The lack of light during the winter months results in a longer period of melatonin secretion, which has been linked to the depressive symptoms

Question 6

AO3: infradian rhythm

Answer 6

lim: external factors
lim: external factors
PMS

Question 7

Infradian rhythms lim: external factors Reinberg

Answer 7

Research suggests that the menstrual cycle is, to some extent, governed by exogenous zeitgebers

Reinberg 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.

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 8

Infradian rhythms lim: external factors Russell

Answer 8

Research by Russell et al (1980) challenges the assumption that the female menstrual cycle is purely controlled by an endogenous infradian rhythm

Daily samples of sweat were taken from women in one group and applied onto the upper lip of women in another group out of contact
Found that menstrual cycles synchronised with the individual donor of sweat despite the fact the groups were kept separate
This suggests that the synchronisation of menstrual cycles is affected by pheromones, an exogenous factor

Question 9

infradian rhythm eval: PMS

Answer 9

Consequences of menstrual cycle

A consequence of the menstrual cycle is that it can lead to premenstrual syndrome (PMS), which affects women a week before menstruation begins (when progesterone rises)
Symptoms include anxiety, depression, aggression, mood swings and fatigue, therefore it has a physiological cause with psychological and physiological symptoms
Research by Dalton (1964) suggests that PMS is associated with an increase in accidents, lower academic performance, suicide and crime

Determinism

This finding has implications for a determinist approach, where biological rhythms are beyond our control and so it is possible to exempt responsibility for our actions
This was such the situation with the case of Ms English who, after driving her car into and killing her married lover after an argument, was granted probation on the grounds that her actions were related to PMS
Argues that severe PMS is akin to a mental disorder, therefore individuals should not be held morally responsible for their actions