Infradian rhythms

Question 1

INFRADIAN

What is an infradian rhythm?

Answer 1

A rhythm lasting longer than a period of 24 hours.

Question 2

INFRADIAN

What is SAD?

Answer 2

Becoming depressed during the winter months and recovering during the summer months. People suffer in ways such as sleepiness, low energy, over-eating and loss of concentration.

Question 3

INFRADIAN
SAD
Discuss research around SAD and the reasoning behind SAD

Answer 3

Research has found in regions of long periods of darkness, the incidence of SAD was a lot higher.
The lack of bright light effects production of melatonin and serotonin. Melatonin and serotonin are secreted when its dark, more darkness means more melatonin which means less serotonin released which is associated with depression.

Question 4

INFRADIAN
SAD
Positive implications

Answer 4

Sitting people in front of artificial light has been proved to help to some extent. Participants placed in front of artificial light at different points of the day found 60% improvement from light in the morning, down to 30% in the afternoon and as little as 5% in a placebo group.
LIGHT IN THE MORNING ACTS AS A ZEITGEBER RESETTING THE BODY CLOCK
Drugs have also been proved to work to alter serotonin levels.
Psychological, social and genetics can also play a part in the reasoning behind SAD e.g. a loss during winter.

Question 5

INFRADIAN

PMS

Answer 5

There has been found that there are similar symptoms in primates during PMS, making it support an endogenous basis.

Question 6

INFRADIAN

PMS-evaluation

Answer 6

However, if PMS is determined by endogenous factors, then we have little free will over actions taken during this time. E.g. A woman drove her car into her lover during an argument, she was placed on probation because it was argued her actions were related to PMS.

Question 7

INFRADIAN
Monthly cycles
Discuss the research of monthly cycles being influenced by exogenous things

Answer 7

When taking a sample from the armpit of women and putting it on the upper lip of other women, it can cause 68% of the other women’s cycles to become synchronised with those of the donors. This is supported by another study which found that 4/5 of the women synchronised.

Question 8

INFRADIAN
Monthly cycles
Evaluation of research on exogenous influences

Answer 8

The sample sizes were small and so lacks population validity.
Any nasal congestion would have effected the result.
The evidence of pheromonal effects in rats and boars is strong e.g when a female boar is exposed to a males boars saliva, they immediately go into the mating position. However, we cannot generalise from animals to humans.

Question 9

INFRADIAN
Monthly cycles
IDA-evolutionary explanation

Answer 9

In some cultures around the world, it is a benefit to be able to have monthly cycles around the same time, it means they can look after each others baby’s.
It has been found that in the presence of men, women tend to have shorter menstrual cycles over a lengthy period of time. This is beneficial because the shorter the cycles, the more they happen and this means ovulation happens more frequently and so there is more of a chance of fertilisation.

Question 10

INFRADIAN
Monthly cycles
Other exogenous influences

Answer 10

Spending time in a dark cave shortened cycle to 25.7 days, showing light has an effect on the cycle.
Menarch happens earlier in blind girls and is more likely to occur in the winter months.