Infradian Rhythms

Question 1

What is an infradian rhythm?

Answer 1

A rhythms lasting more than 24hours periodicity

Question 2

What is the main infradian rhythm?

Answer 2

The human menstrual cycle

Question 3

How long does the human menstrual cycle last?

Answer 3

28 days

Question 4

Outline the human menstrual cycle

Answer 4

Hypothalamus releases GRH which stimulates the pituitary gland to produce FSH causing follicles to mature.
The maturing follicles release oestrogen which causes the lining of the uterus. When the oestrogen reaches an optimum point, LH is produced which causes the most mature follicle to burst open and release an ovum (ovulation). An ovum is carried towards the uterus where fertilisation occurs

Question 5

What does Russel (1980) show?

Answer 5

The role of exogenous zeitgebers in infradian rhythms

Question 6

What is the main endogenous pacemaker in the human menstrual cycle?

Answer 6

Hormones

Question 7

Outline Russel (1980)

Answer 7

There are pheromones (odourless biochemicals in the air) which is thought to be involved in the synchronisation of menstrual cycles. They collected sweat everyday from donor, mixed it with alcohol to remove bacteria and odour, and applied it under the noses of volunteers. The menstrual cycles soon became synchronised so evidence for the role of pheromones

Question 8

An advantage of Russel (1980)

Answer 8

Supported by McClintok (1971) who synchronised menstrual cycles through pheromones

Question 9

What are the consequences of the menstrual cycle?

Answer 9

PMS affects you a week before menstruation begins, symptoms include depression, mood swings and aggression. Dalton (1964) found PMS associated with an increase in accidents, suicides and crime

Question 10

What are 2 evaluative points about the human menstrua; cycle?

Answer 10

1) Exogenous zeitgebers in the form of pheromones

2) Consequences of the human menstrual cycle in terms of PMS

Question 11

What did Dalton (1964) show?

Answer 11

PMS associated with an increase in accidents, suicides and crime

Question 12

Name 2 other infradian rhythms

Answer 12

Seasonal Affective Disorder (SAD) and hibernation

Question 13

What is Seasonal Affective Disorder?

Answer 13

When seasonal changes affect behaviour - feel depressed in the winter and elated during the summer

Question 14

What causes Seasonal Affective Disorder?

Answer 14

The absence of light which increases the levels of melatonin

Question 15

What evidence is there for Seasonal Affective Disorder?

Answer 15

Depression is most likely in northern than southern countries

Question 16

What has been suggested to help Seasonal Affective Disorder?

Answer 16

Rosenweig suggested light therapy

Question 17

What evidence is there for hibernation?

Answer 17

Pengelley & Fisher (1959)

Question 18

Outline Pengelley & Fisher (1959)

Answer 18

Looked at North American ground squirrels which normally hibernate in late autumn when their body temperature drops significantly and respiration slows. They were studied in the lab, and despite constant temperature and light, hibernation still occurred suggesting endogenous

Question 19

Name 2 IDA points for infradian rhythms

Answer 19

1) Determinist

2) Real-world application

Question 20

Explain why infradian rhythms can be deterministic

Answer 20

PMS has been used as a legal defence as Dr Dalton has argued severe PMS is similar to a mental disorder and they should not be held responsible for their actions, suggesting it is out of our control. However, evidence that we can ‘will’ our rhythms to change. Born (1999) told ppts to wake up earlier than usual and found higher levels of stress hormone ACTH (waking up process) than normal at designated time and thus woke up earlier

Question 21

What does Born (1999) show?

Answer 21

That we can ‘will’ our rhythms to change and thus control them

Question 22

Explain the real-world application of infradian rhythms

Answer 22

The understanding that darkness plays a key role in SAD has led to therapies like phototherapy which uses very strong lights (equivalent to daylight) to change the levels of serotonin and melatonin. It has been reported that it relieves them of their feelings but placebo effect but Eastman (1998) found placebo condition less effective, but 32% still improved with the placebo alone

Question 23

Outline Eastman (1998)

Answer 23

Found placebo condition less effective, but 32% still improved with the placebo alone

Question 24

What does Eastman (1998) show?

Answer 24

Placebo condition less effective and still works to a certain extent