Biopsychology: Infradian and Ultradian rhythms Flashcards
What is an infradian rhythm?
A type of biological rhythm that is longer than 24 hours
What is are examples of an infradian rhythm?
The menstrual cycle and seasonal affective disorder
How is the female menstrual cycle an example of a rhythm?
A typical cycle takes approximately 28 days. During each cycle the riding levels of oestrogen cause ovulation. After ovulation, progesterone helps the womb lining to grow thicker to ready the body for pregnancy. If pregnancy does not occur the egg is absorbed into the body, the womb lining comes away and leaves the body.
Who studied the menstrual cycle?
Stern and McClintock
What did Stern and McClintock do?
29 women with a history of irregular periods.
Samples of pheromones were gathered from 9 of the women at different stages of their cycles via a cotton pad in their armpit.
The pads were frozen and rubbed on the upper lip of the other participants.
What were the findings of Stern and McClintock?
They found that 68% of women experienced changes to their cycle which brought them closer to them ‘odour donor cycle’.
This suggests that the cycle is an endogenous system affected by exogenous factors.
What is an ultradian rhythm?
A type of biological rhythm that is shorter than 24 hours.
What is an example of an ultradian rhythm?
Stages of sleep
What happens in stages 1 and 2?
It’s light sleep where the person may be easily woken..
Brainwaves start to become slower and more rhythmic, and they become even slower as sleep becomes deeper.
What happen stages 3 and 4?
This involves delta waves, which are slower still and have a greater amplitude than earlier wave patterns. This is deep sleep or slow wave sleep, difficult to rouse someone at this point.
What happens in stage 5?
REM sleep, the body is paralysed yet brain activity speeds up significantly in a manner that resembles that awake brain.
What are the evaluation points for and ultradian rhythms?-
Evolutionary basis of the menstrual cycle
Methodological limitations in synchronisation studies
Evidence Evidence for stages
Animal studies
Evaluation point: Evolutionary basis of the menstrual cycle
For our ancestors it may have been advantageous for females to menstruate together and therefore fall pregnant at the same time. This would mean that new-borns could be cared for collectively within a social group and increase survival.
However it has also been said that it if too many cycle together in a social group then it can create competition for the highest quality males, from this view avoidance of synchrony would be the most adaptive evolutionary strategy.
Evaluation point: Methodological limitations in synchronisation studies
There are many factors that can effect a woman’s menstrual cycle, including stress, diet, exercise that might act as confounding variables. This means that any supposed pattern of synchronisation is no more than would have been expected to occur by chance.
Evaluation point: Evidence Evidence for stages
Evaluation point: Animal studies
