Infradian rhythms Flashcards
What are infradian rhythms?
Biological rhythms that last longer than 24 hours, such as weekly, monthly, or yearly cycles
What is a monthly example of an infradian rhythm
The female menstrual cycle
What regulates the menstrual cycle?
Hormones that promote ovulation and prepare the uterus for potential fertilisation
When does ovulation occur during the menstrual cycle?
Roughly halfway through the cycle, when oestrogen levels are at their highest.
How long does ovulation typically last?
16–32 hours
What happens after ovulation?
Progesterone levels increase to prepare the uterus for possible implantation of an embryo
What is the average length of a menstrual cycle?
About 28 days, but it can range from 23 to 36 days
What is an annual example of an infradian rhythm?
Seasonal Affective Disorder (SAD)
What is Seasonal Affective Disorder (SAD)?
A yearly cycle of seasonal depression, often occurring in winter.
What causes SAD?
Increased melatonin secretion due to reduced light during winter, linked to depressive symptoms
What gland secretes melatonin?
The pineal gland, primarily at night.
Seasonal Affective Disorder (SAD): Practical application
Terman (1988)
- SAD is more prevalent in Northern countries with longer winter nights.
- In Northern New Hampshire, SAD affects 10% of residents, while in southern Florida, only 2% are affected.
- This suggests SAD is influenced by light exposure, affecting melatonin levels.
Evolutionary Perspective on Infradian Rhythms
Evolutionary psychologists claim synchronised menstrual cycles provide childcare benefits.
Synchronisation allows multiple mothers to share childcare responsibilities, offering an evolutionary advantage.
