Biopsychology: Ultradian and Infradian Rhythms Flashcards
what’s infradian rhythms?
a type of biological rhythm with a frequency of less than one cycle in 24 hours such as menstrual cycle or seasonal affective disorder.
what can be said about the menstrual cycle?
it’s governed by monthly changes in hormone levels which regulates ovulation. during each cycle, rising levels of oestrogen causes the ovary to develop an egg and release it. the cycle takes 28 days to complete.
what’s McClintock’s research into infradian rhythms?
he involved 29 women who had irregular periods. samples of pheromones were gathered from 9 of the women at different stages of their menstrual cycle via a cotton pad on their armpits. the pads were worn for 8 hours to ensure the pheromones were picked up. the pads were then treated with alcohol and frozen to be rubbed on the upper lip of other participants. he found that 68% experienced changes to their cycle which brought them closer to the cycle of their odour donor.
what’s seasonal affective disorder (SAD)?
SAD is triggered during the winter months when the number of daylights become slower. it’s a yearly cycle. the hormone melatonin is the cause SAD. during the night, the pineal galnd secretes melatonin until dawn when there’s an increase of light, during the winter, the lack of light means melatonin is secreted for longer, which has a knock-on effect on the production of serotonin.
what’s ultradian rhythms?
a type of biological rhythm that happens more than once in a 24 hour cycle.
what’s the stages of sleep?
stage 1 and 2 = sleep escalator, the light sleep where a person is easily woken, brainwaves become slower and more rhythmic. stage 3 and 4 = delta waves, slower and greater amplitude. stage 5 = REM sleep, the body is paralysed and brain activity speeds up.
what’s the evolutionary basis of the menstrual cycle? (A03)
menstrual synchrony is thought to have a evolutionary basis. it’s advantangeous for females to menstruate together and then fall pregnant around the same time, meaning new-borns could be cared for collectively within a social group increasing the chances of offspring’s survival. the validity has been questioned by Schank who argued too many females cycling together within a social group as it produces competition for the highest quality male.
what’s the methodological limitations of sychronisation studies? (A03)
there are too many factors that may effect change to a women’s menstrual cycle including stress, changes in diet, exercise that act as confounding variables. this means any supposed pattern of sychronisation is no more than would have been expected to occur by chance. research involves small samples of women and relies on participants self-reporting their own cycle.
what’s the evidence that supports the idea of the distinct stages in sleep? (A03)
Dement + Kleitman monitored the sleep patterns of 9 adult participants in a sleep lab. Brainwave activity is recorded on a EEG and the researchers controlled the effects of caffeine and alcohol. REM activity was highly correlated with the experience of dreaming. replication of this study noted similar findings though the small sample size of the original study has been criticised.
