Infradian And Ultradian Rhythms Flashcards
(23 cards)
What is an infradian rhythm
A biological rhythm that lasts longer than 24 hours, usually monthly or seasonally
How long is the menstrual cycle
24-35 days
What are the 3 stages to the menstrual cycle
-Ovulation - increased levels of oestrogen develops and releases the egg
-Progesterone is then released to thicken the lining of the womb for pregnancies
-If pregnancy does not occur within 2 weeks, the lining sheds and you menstruate
What are the exogenous impacts on the menstrual cycle
Other women’s pheromones
Who studied the effect of other women’s pheromones on menstrual cycle length
McClintok
McClintocks procedure
-29 women with irregular periods
-9 rubbed cotton pads under their armpits at different stages of their cycle
-Theses were then frozen, treated with alcohol and then rubbed on the lips of the other 20 women
McClintock’s findings/conclusions
68% of women experienced changes in their cycle which correlated to that of their donor
Pheromones effect the length of menstrual cycles
What is SAD
Seasonal affective disorder
Characteristics of SAD
-It’s a depressive disorder characterised by the DSM-5 as a form of depression
-General lack of activity
-Slow mood
How is SAD caused
-Disruption in the sleep/wake cycle
-Large amounts of melatonin produced
-Could have a knock on effect to the production of serotonin
What are ultradian rhythms
24 hour biological clocks
How long do all 5 stages last
90 minutes
Stages 1-2
-Sleep escalator
-Light sleep, easily awoken
-Brainwaves start as slow and rhythmic (alpha waves) then they become even slower and experienced (theta waves)
Stages 3-4
-Sleep sleep
- Involves delta waves which are even slower with a much greater amplitude
-Difficult to wake up
Stage 5
REM-rapid eye movement
-The body is paralysed but brain activity speeds up to a manner that resembles an awake brain
-Fast, jerking movement of eye under eyelid
-Correlated with dreaming
How are ultradian rhythms studies
EEG
Evolutionary basis of the menstrual cycle synchrony
-For our ancestors, it may have been advantageous to menstruate together in order to fall pregnant at the same time
-New borns can be cared for collectively by the group
-Supports out evolutionary psychology and is therefore more objectively valid
Contradictions to the evolutionary basis of menstrual cycle synchrony
Schank
If there were too many females cycling throughout a social group, that would cause more competition for high quality males between females leading
This lowers the fitness of potential offspring
An avoidance of synchrony should be naturally selected
Methodological limitations of studying female menstrual cycle
-Confounding variables that could impact the length of a women’s cycle like stress or health
-Small sample size so the patterns of synchronisation may not be valid
Evidence supporting the distinct stages of sleep
Dementia and Kleitman
-Monitored sleep patterns on 9 adult ppt in a sleep lab using EEG
-REM was highly correlated with experience of dreaming with brain activity varying depending on how vivid the dreams were
Practical application SAD
-Phototherapy
-Light box that stimulates very strong light in the mornings and the evenings
-Resets melatonin levels in people with SAD in up to 60% of individuals
Research support SAD
Rates of SAD are more common in Northern countries
New Hampshire - 10%
South Florida - 3%
Methodological issues in studying the stages of sleep
-Has to be done in a controlled lab study
-Natural sleep patterns may not be accurately displayed due to levels of discomfort
