Infradian Rhythms And Ultradian Rhythms Flashcards
One example of an infradian rhythm is…
Menstrual cycle
Quickly explain what hormones are involved in the menstrual cycle
Oestrogen regulates ovulation
Progesterone readies body for pregnancy eg. Womb lining
(See Oxytocin)
Who did research into synchronising the menstrual cycle?
Stern and Mclintock.
Describe stern and Mclintock procedure
29 women with a history of irregular periods.
Samples of pheromones gathered from 9 women at different stages in menstrual cycle, via cotton pads from armpit.
Pads worn for 8hrs. Pads then frozen and treated with alcohol.
On day one of cycle pads from start of cycle worn on upper lip of PPS.
Describe stern and Mclintock findings
68% of women experienced changes to cycle closer to the odour donor.
Give an example of a circannual rhythm
Seasonal affective disorder (SAD)
What is SAD
A form of depression triggered in the winter months regulated by melatonin.
What is the pineal gland’s role in SAD?
During night pineal gland secrets melatonin until dawn. During winter secretion for longer which has a nock on effect on serotonin.
On strength of infradian rhythm research (AO3)
Evolutionary basis
Menstrual synchronisation can be explained by natural selection. May have been advantageous for women to menstruate together and become pregnant at same time. Allows babies who lost their mother during or after childbirth have access to breast milk. Increase survival.
One limitation of infradian rhythm research (AO3)
Many factors affect the menstrual cycle eg. Stress, diet, exercise etc
Confounding variables, therefore only supposed pattern in synchronisation is no more than would have been due to chance. Explains why other studies failed to replicate findings.
One example of ultradian rhythm is sleep stages. Describe this
5 sleep stages which all together span 90 mins. Cycle continues throughout the night (monitored by EEG)
What is sleep stages 1+2
Light sleep
Brain waves high frequency and short amplitude. Alpha waves
What is sleep stages 3+4
Deep sleep
Delta waves, lower frequency and high amplitude
What is stage 5
REM sleep
Theta waves, dreams occur
One strength of ultradian rhythm research is improved understanding (AO3)
Improved understanding in age related changes in sleep. Observed that SWS reduces with age. Growth hormone produced in SWS so why it reduces with age. Therefore sleep deficiency may explain issues in old age eg. Reduced alertness,
One limitation of ultradian rhythm research is individual differences (AO3)
Significant variation between people. Found large differences between PPS sleep stage, mostly 3 and 4. Suggested these differences are biologically determined.
Difficult to describe sleep in meaningful way.
