Infradian and Ultradian rhythms Flashcards
What is an infradian rhythm?
A biological rhythm that occurs to a period of more than 24 hours
What are two examples of Infradian rhythms?
Menstrual cycle
Seasonal affective disorder
What is the role of oestrogen in the menstural cycle?
Rising levels of oestrogen cause the ovary to release an egg
What is the role of progesterone in the menstural cycle?
Thickens the lining of the womb, to ready it for pregnancy
What is seasonal affective disorder (SAD)?
A depressive disorder with a seasonal pattern, usually happening in winter months
What causes SAD?
As it is dark in the winter, more melatonin is secreted for a longer time.
This leads to decreased serotonin levels
What is a ultradian rhythm?
Span over less than a day, less than 24 hours
What is an example of an ultradian rhythm?
Sleep cycle
What waves in the brain do sleep stages 1-2 have?
Alpha and beta
What happens to the body during stages 1-2?
Heart rate slows and temperature drops
What waves are present in the brain during sleep stages 3-4?
Delta waves
What is another name for sleep stage 5?
REM
What happens during sleep stage 5?
The body is paralysed and brain activity resembles an awake person
What is a weakness of explaining the menstrual cycle as an infradian rhythm?
Individual factors may change the length of the menstrual cycle such as stress
What did tucker et al find about sleep stages?
He found large differences between participants in the duration of stages 3 and 4.
This makes it difficult to describe ‘normal sleep’
