biopsychology - infradian and ultradian rhythms Flashcards
what is an infradian rhythm
biological rhythm with a frequency of less than one cycle in 24 hours
what are 2 examples of an infradian rhythm
menstrual cycle and seasonal effective disorder
what is an ultradian rhythm
biological rhythm with a frequency of more than one cycle in 24 hours
what are 2 examples of ultradian rhythms
stages of sleep, blood circulation
outline the menstruation cycle ( example of infradian rhythm )
10/16 days before period the hypothalamus sends signals to pituitary gland to release oestrogen. This causes ovary to develop an egg. Progesterone is released to thicken lining of womb for pregnancy. If pregnany does not occur, egg is absorbed and lining of womb is shed, reduction in secretion of oestrogen and progesterone. This begins day 1 of the cycle again. Typical cycle is 28 days
what exogenous zeitgebers can effect the menstrual cycle (infradian cycle)
stress, diet, medication
what endogenous pacemakers can effect the menstrual cycle
hormones released by pituitary gland
The infradian cycle of mensturation is an endogenous system, but can be affected by exogenous factors. Outline the study that demonstrates this
Stern and Mclintock studied 29 women with a history of irregular periods. Gathered samples of pheremones from 9 of the women at different stages in their cycle via a cotton pad placed in armpit.
Pad warn for 8 hours treated with alcohol and frozen, rubbed on the upper lip of other pps.
What were the findings of Stern and Mclintock’s study?
68% of women experienced changes to their cycle which brought them closer to the cycle of their ‘odour donor’
What conclusions can be drawn from stern and Mclintock’s study?
Endogenous pacemaker (pituitary gland and hormones) became entrained by the exogenous zeitgeber (pheremones from other women). This meant the EZ had shifted the EP to bring production of oestrogen to be in sync with the ‘odour donor’.
(stern and mclintock) only 68% of women experienced changes to their cycle - what could be said about the 32% that didn’t
There are individual differences in that some people are more influenced by pheremones than others.
what is seasonal affective disorder
depressive disorder which has a seasonal pattern, symptoms such as low mood and lack of activity are triggered during winter months when daylight hours become shorter.
what are the possible causes of SAD
accumulative disruption to sleep/wake cycle - prolonged periods of daily darkness
during winter the lack of light means melatonin secretion lasts which has a knock on effect on production of serotonin
What did Sanassi find that supports the idea that SAD is caused due to a lack of light
Light boxes improved symptoms for 80% of people suffering, Shows SAD is caused by lack of light for most, but not all.
how many stages of sleep are there and how long do they last for
5 stages of sleep that last for 90minutes.
outline the 1 and 2 stage of sleep (ultradian rhythm)
Light sleep where person can be easily woken, brain waves are high frequency , short amplitude in stage 1.
In stage 2 alpha waves continue but there are occasional random changes in pattern called sleep spindles.
outline what occurs during sleep stage 3 and 4
deep sleep, brain waves are delta waves - low frequency high amplitude. difficult to wake someone, growth hormones are released
outline what occurs during sleep stage 5
body is paralysed by the pons, brain produces theta waves and REM occurs. dreams most likely to occur here.
what is a limitation of Stern and Mclintock’s research (AO3)
research findings are inconsistent and have low external reliability. could be due to small pps study and lack of control over extreneous variables such as stress, diet exercise.
To be 100% valid should only be exposed to pheromones of women in study, this is impossible as pure isolation is unethical.
What was Dement’s contribution to psychology (AO3)
Investigated pps in sleep labsm first researcher to use an EEG to measure sleep.This paved way for all future research investigating sleep, first investigator to validate existance of sleep stages and develop a scientific method for measuring and comparing individuals. Therefore can identify what ‘normal’ sleep is and diagnose people with specific sleep disorders.
What did Dement find (AO3)
found pps went through 5 stages of sleep characterised by specific wave activity.
Why is investigation into sleep so important (AO3)
knowledge can be used to improve people’s experience of sleep by designing apps and technology that can measure sleep by temp, and suggest when to sleep and when to wake up based on which stage of cycle you are in.
What is the benefit of understanding the influence EZ have on infradian rhythms such as SAD
Led to development of light therapy, involves having a light box that a patient will turn on in the morning after waking up, or spend time in front of whilst completing tasks to increase serotonin production by the pineal gland. This compensates for the lack of light in the winter and helps reduce symptoms.
