infradian rhythms Flashcards
(15 cards)
What is an infradian rhythm?
An infradian rhythm is a biological rhythm that lasts longer than 24 hours. It can occur weekly, monthly, or annually.
Give two examples of infradian rhythms.
The menstrual cycle (monthly) and Seasonal Affective Disorder (SAD – annually).
What regulates the female menstrual cycle?
Hormones that promote ovulation and prepare the uterus for fertilisation.
When does ovulation occur and how long does it last?
Ovulation occurs around the midpoint(day 14) of the cycle, when oestrogen levels are highest, and lasts approximately 16–32 hours.
What happens hormonally after ovulation?
Progesterone levels increase to prepare the uterus for potential embryo implantation.
What is the average length of the menstrual cycle?
About 28 days, though it can vary from 23 to 36 days among individuals.
What is Seasonal Affective Disorder (SAD)?
A type of depression that occurs during the winter months, linked to a yearly infradian rhythm.
What causes SAD, according to psychologists?
Increased melatonin secretion during longer nights in winter, due to reduced light exposure, which is linked to depressive symptoms.
Which gland is responsible for melatonin secretion?
The pineal gland.
What are exogenous zeitgebers?
External factors that influence biological rhythms, such as light or pheromones.
What did Reinberg (1967) find in his cave study on infradian rhythms(menstrual)?
A woman who spent 3 months in a cave with limited light had a shortened menstrual cycle (from 28 to 25.7 days), suggesting light influences infradian rhythms.
What did Russell et al. (1980) discover about menstrual cycle synchronisation?
Female menstrual cycles can synchronise through exposure to other women’s pheromones, such as sweat transferred to the upper lip, indicating the influence of external cues.
What does the Russell et al. (1980)(sweat on upper lip pheromones) study imply about biological rhythm research?
It suggests a need for a holistic approach, considering both endogenous and exogenous factors, rather than a purely reductionist view.
What did Penton-Volk et al. (1999) find regarding mating preferences and menstrual cycles?
Women preferred more masculine faces at the most fertile stage of their cycle and more feminised faces at the least fertile stage, suggesting infradian rhythms influence sexual preferences and behaviour.
What do Penton-Volk et al.’s findings indicate about infradian rhythms?
That they are important regulators of behaviour, particularly sexual behaviour.
