BIOLOGICAL RHYTHMS - INFRADIAN AND ULTRADIANRHYTHM Flashcards
what is an infradian rhythm?
a type of bio rhythm which has a frequency of less than one cycle in 24 hours e.g. menstruation or SAD
what is the female menstruation cycle governed by?
monthly changes in hormone levels which regulate ovulation
what does the menstrual cycle refer to?
time between first day of period, when womb lining sheds to the day before her next period
how long does a typical cycle last?
28 days but 24-35 is considered normal
the rising level of what hormone causes the ovary to develop an egg and release it?
oestrogen
what hormone is present after ovulation? (when egg gets released)
progesterone
what does the hormone progesterone do?
helps the womb lining grow thicker, readying the body for pregnancy
what happens if pregnancy doesn’t occur?
egg is absorbed into the body, the womb lining comes away and leaves the body (the menstrual flow)
who conducted research to show menstrual cycle can be influenced by exogenous factors?
Stern and McClintock
what did Stern and McClintock demonstrate?
how menstrual cycles synchronise as result of inf of female pheromones
who were McClintock’s sample?
29 women with irregular periods
what did McClintock do?
get samples of pheromones from 9 women at diff stages of mens w/ cotton pas
how long were pads worn on armpits?
8 hrs to make sure pheromones picked up
what happened to cotton pads after collection?
treated with alcohol, frozen and rubbedon upper lip of other ppts
what happened on day 1 and day 2 and so on in Stern and McClintock’s exp?
day 1 - pads from start of mens applied to 20 ppts
day 2 - all ppts given pad and so on
what were the findings of Stern and McClintock’s exp?
68% of ppts exp changes to cycle, bringing them closer to cycle of odour donor
what is SAD?
seasonal affective disorder, diagnosed as mental disorder in DSM-5
why is SAD an infradian rhythm?
symptoms such as low mood and interest triggered by winter months when number of daylight hrs are shorter
what type of infradian rhythm is SAD?
circannual as it is subject to a yearly cycle
how can SAD be seen as a circadian rhythm?
exp of SAD due to disruption of sleep/wake cycle, attributed to prolonged periods of daily darkness
what have psychologists hypothesised about the cause of SAD?
hormone melatonin implicates it
what does the pineal gland do during night?
secretes melatonin until dawn when there is an increase of light
what happens to melatonin during winter?
lack of light in the morning means secretion of melatonin goes on for longer, has knock on effect on production of serotonin linked to depression
what is an ultradian rhythm?
a biological rhythm that has a fequency of more than one cycle in 24 hours
what is one of the most intensely research ultradian rhythms?
srages of sleep
how many stages of sleep are there and altogether how long do they last?
5 distinct stages that last about 90 mins
how are each of the stages of sleep characterised?
different level of brainwave activity monitored using an EEG
what are stages 1 and 2 of sleep known as?
light sleep
in stages 1 and 2 of sleep, brainwaves are…
slowed down and more rhythmic (alpha waves) and becoming slower as sleep becomes deeper (theta waves)
what are stages 3 and 4 of sleep known as?
deep sleep or slow wave sleep, hard to wake someone up
what brainwave does stages 3 and 4 have?
delta waves which are slower and have greater amplitude than alpha and beta
what is stage 5 of sleep known as?
REM sleep (rapid eye movement)
what happens to the body and brain in REM sleep?
body is paralysed but brain activity speeds up significantly representing awake brain
why is REM sleep named that?
fast activity of eyes under eyelids during sleep stage
what has research suggested about REM sleep?
highly correlated with experience of dreaming
give 3 evaluation points of infradian and ultradian rhythms?
+ evolutionary basis of menstrual cycle
+ evidence support stages of sleep
- methodological limitations in synch studies
there is a ________ _____ for menstrual cycle?
evolutionary basis
how is there an evolutionary basis of menstrual cycle?
it is advantageous for females to menstruate together and fall pregnancy around the same time
why is it an advantage for females to menstruate together?
new-borns could cared collectively within a social group increasing chances of offspring’s survival
how can the validity of the evolutionary be questioned?
Schank says if too many females synchronise, create competition to get highest quality males, so should avoid synchrony and be naturally selected
there is _________ to support the stages of sleep
evidence
who conducted research to support the stages of sleep?
Dement and Kleitman
what did Dement and Kleitman do?
monitor the sleep patterns of 9 adult ppts in sleep lab
what did researchers control?
controlled effects of caffeine and alcohol
how did Dement and Kleitman get information?
brainwave activity recorded from EEG
what was REM sleep highly correlated with?
w/ exp of dreaming, brain activity varied on how vivid they were, ppts woken during dreaming had v accurate recall
what does Dement and Kleitman’s research suggest?
REM sleep is an important component of the ultradian sleep
