111339
Description
Mind Map by harry_bygraves, updated more than 1 year ago
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Created by harry_bygraves
almost 11 years ago
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Infradian Rhythm
- Infradian rhytms are cycles lasting more than 24 hours. Like
mestrual cycle, regulated by hormone secretions. Originally thought
to be controlled by the hypothalamus acting as an endogenous
pacemaker, evidence shows exogenous zeitgebers play a part too.
- The menstrual cycle is regualted by hormones whose release is
controlled by the hypothalamus. the typical menstrual cycle is
approx. 1 month in length and for women living on theor own
appears to be governed solely by endogenous mechanisms.
However, there appears to be an exogenous factor where females
living together find their menstrual cycles become synchronised.
- Turke (1984) has suggested that this has an evolutionary
advantage because females who have synchronised menstrual
cycles are likely to get pregnant and give birth at similar times.
this would allow the women to share child rearnig duties
- Turke (1984) has suggested that this has an evolutionary
advantage because females who have synchronised menstrual
cycles are likely to get pregnant and give birth at similar times.
this would allow the women to share child rearnig duties
- In addition, it has been noted that females who
work in close proximity to males have shorter
menstrual cycles, possible in response to male
phermones. Shorter menstrual cycles would
increase the opportunities to get pregnant
- McClintock and Stern, menstrual synchronis studies.
Identified the synchronisation of female menstruation when
she observed that the menstrual cycles amoung her
dormitory mates become synchronised. After further
research she concluded that the synchronisation of the
menstrual cycles amoung 135 females was caused by
pheromones transmitted through social interaction. It was
initially suggested that there may be a specific pheromone
that affects the timing of other female menstrual cycles
- The second infradian rhythm is seasonal
affective disorder (SAD). SAD is characterised
by feeling of abnormal depression during the
darker winte rmonths and a return to 'normal'
feeling as the days get longer. SAD has been
linked to melatonin levels which increase
when there is not enough light. The higher
than normal levels of melatonin may give rise
to the feeling of depression
- Rosenzweig et al (1980) found that
winter darkeness was associated
with levels of melatonin and reports
of increased feeling of depression
- Lewy et al. (1980) found that exposure to bright lights at night
reduces the amount of melatonin produced. However, this means
that while winter can cause SAD bright lights may also leed to sleep
problems and insomnia if the lights are used close to bed times
- Rosenzweig et al (1980) found that
winter darkeness was associated
with levels of melatonin and reports
of increased feeling of depression
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