Infradian And Ultradian Rhythms Flashcards
What is an infradian rhythm and example
Type of biological rhythm that lasts more than 24 hours eg menstrual cycle/ seasonal affective disorder
What is an ultradian rhythm and example
A type of bio rhythm that lasts Under (under for ultradian) 24hrs eg the stages of sleep
What is the menstrual cycle
Governed by monthly changes in hormone levels (oestrogen preovulation and progesterone post ovulation) which regulate ovulation
-biological aspects involve releasing the egg, thickening of the womb lining and losing the womb during menstruation
-approx 28 days
-level of hormone acts as endogenous pacemakers keeping the biological process to time- acts as internal body clock
Expand on McClintock’s study
-demonstrated how menstrual cycles may synchronise as a result of the influence of female pheromones
-involved 29 women with a history of irregular periods, samples of pheromones collected from women at dif stages of their cycle via a cotton pad placed in their armpit
-pads treated with alcohol and frozen and rubbed on upper lip of the other ppts
-found 68% of women experienced changes to their cycle which brought them closer to the cycle of their odour donor
What is seasonal affective disorder and what causes it
-depressive disorder with seasonal pattern of onset, described as mental disorder in DSM-5
-main symptoms are persistent low mood
-circannual rhythm as it is subject to yearly cycle
-hypothesised that hormone melatonin which is released when it’s dark as in winter, affects release of serotonin
Expand on sleep cycle
Five distinct stages of sleep that span approx 90 minutes, called sleep escalator
-each stage characterised by dif level of brainwave activity which can be monitored using EEG
-stage 1 and 2: light sleep, brainwave patterns become slower and more rhythmic
-stage 3 and 4: involve delta waves which are slower and have greater amplitude, this is deep sleep
-stage 5(REM): body paralysed yet brain activity speeds up significantly, jerky activity of eyes under eyelids
Expand on methodological limitations in synchronisation studies
-many uncontrolled factors may effect changes in woman’s menstrual cycle eg stress/changes in diet which might act as confounding variables
-means any supposed pattern of synchronisation as seen in study by McClintock is no more than would have been expected to occur by chance
-research only involved small sample of women and relied on ppts self-reporting the onset of their own cycle
-reduces validity of conclusion that pheromones of others affect menstrual cycle
Expand on strength that there is evidence to support the idea of distinct stages in sleep and however point
-study by Dement monitored sleep patterns of 9 ppts in sleep lab, brainwave activity recorded on an EEG and the researchers controlled for the effects of caffeine and alcohol
-found REM activity during sleep highly correlated with the experience of dreaming, brain activity varied according to how vivid dreams were and ppts woken during dreaming reported very accurate recall of their dreams
-supports idea of distinct stages of sleep cycle
H: small sample/ lacks ecological validity as situation in which ppts had to sleep was unusual and may have affected their sleep patterns
Expand on strength that there is practical application of understanding of SAD and however point
-led to phototherapy treatment which simulated very strong light in morning and evening thought to reset melatonin levels, meaning serotonin levels can increase, found to relieve symptoms in up to 60% of individuals
-effective treatment for more than half of patients
H: same study recorded placebo effect of 30% using negative ion generator ppts were told was another form of treatment, also phototherapy not effective in all ppts suggesting environmental factors also involved in development of SAD
Expand on strength for effect of external factors on menstrual cycle from Reinberg
-examined a woman who spent three months in a cave with only a small lamp to provide light and noted that her menstrual cycle shortened from usual 28 days to 25.7 days
-suggests lack of light (exogenous zeitgeber) in the cave affected her menstrual cycle demonstrating the effect of external factors on infradian rhythms
