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BIOLOGICAL RHYTHMS: INFRADIAN AND ULTRADIAN - Coggle Diagram
BIOLOGICAL RHYTHMS: INFRADIAN AND ULTRADIAN
infradian rhythms
Example: menstrual cycle is driven by the endocrine system as hormone levels fluctuate under the control of the pituitary gland
however, exogenous zeitgebers, such as light and odour (pheromones), are also thought be involved
a type of biological rhythm that last longer than 24 hours eg. menstrual cycle or SAD
average length: 28 days
McClintock and Stern 1998
collected daily sample of 'odourless compounds' (sweat) from the armpits of a group of 9 women, which was then rubbed on the upper lips of a group of 20 women
when women received the odourless compound (sweat) from the armpits in the latter half of their menstrual cycle, their menstrual cycle was shortened
investigated the effects of female pheromones (exogenous zeitgeber) on the menstrual cycle
if the sweat was collected at the begging, it lengthened the cycle of those who had received
this shows that the menstrual cycle of a women can be altered by pheromones (exogenous zeitgebers)
Reinberg 1976
her sleep-week cycle lengthened slightly and her menstrual cycle became shorter during her stay in a cave
her menstrual cycle shortened to 25.7 days
documented the duration of women's menstrual cycle during and after she spent 3 months in a cave, with only dim lighting
suggests that low levels of light in the cave affected the women's menstrual cycle
however, small sample....
Seasonal Affective disorder SAD
the hormone melatonin causes thus as it is secreted when its dark
darkness means more melatonin which means less serotonin
individuals experience severe depression during the winter months and recover during the summer
low levels of serotonin are associated with depression
treating SAD
phototherapy: uses very string lights (equivalent to full daylight) to change levels of melatonin or serotonin
ultradian rhythms
eg. sleep stages, basic rest-activity cycle BRAC
last less than 24 hours, occur more than once in a 24 hour period
sleep stages
stage 1 and 2 - light/shallow sleep
stage 3 and 4 - deep sleep, brainwaves slow and their breathing and heart rate decrease
different stages of sleep are measured by the electrical activities of the brain, with each stage showing a distinct EEG pattern
in deep sleep/slow wave sleep SWS, most of the body's physiological repair work is undertaken and important biochemical processes occur eg production of growth hormones
stage 5 - REM sleep, most dreaming occurs
Dement and Kleitman 1957
there were high incidences of dream recall when ppts are awakened during REM sleep. if awakened in other stages, very few reported dreaming
conclusion: the stages of sleep follow a typical pattern throughout the night, dreams mostly occur in REM sleep
everyone had periods of REM sleep
connected 9 ppts (7 males/ 2 females) to EEG and took measurement throughout a nights sleep
:cry: lab study, artificial environment, atypical reaction
:smiley: EEG is an objective measure and is therefore scientific