Biological Rhythms - Ultradian and Infradian

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Everything you need to know for an essay on ultradian and infradian rhythms
chloe.brandon
Flashcards by chloe.brandon, updated more than 1 year ago
chloe.brandon
Created by chloe.brandon over 8 years ago
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Question Answer
How long does an Ultradian Rhythm last for? Less than 24 hours
What is an example of an ultradian rhythm? Stages of Sleep
How many stages of sleep are there? 5
What are the first 4 stages of sleep called? NREM (non rapid eye movement)
What is the 5th stage of sleep called? REM (rapid eye movement)
How long does one sleep cycle last? 90 minutes
What are stages 1 and 2, how are they characterised? Light sleep. This is characterised by a change in the electrical activity of the brain.
What type of waves does the 'awake' brain produce? Beta
What does a beta wave change to in light sleep when you become more relaxed? Alpha wave
What happens to these waves as you fall asleep? They slow down further (greater frequency). This is a theta wave.
What are theta waves also accompanied by? Bursts of energy - increased wave frequency (sleep spindles) and increased wave amplitude (K complexes).
What are stages 3 and 4 called and what are they characterised by? Slow wave sleep (SWS) and even slower delta waves
What is it difficult to do in SWS? wake somebody up, although a person is not unconscious and they will STILL be aroused by something like their baby crying
What happens in SWS? Most of the body's repair work takes place such as the production of growth hormones and mending of cells.
What happens in REM sleep? There is a fast desynchronised EEG activity resembling that of the brain when it is awake. It is thought that dreaming takes place during this stage.
What happens as the sleep stage cycle continues throughout the night? The SWS period gets shorted whilst the REM period gets slightly longer
How long is a sleep cycle in infants? 60 minutes
What is an issue with studies on REM sleep? The assumption that this stage of sleep is for dreaming
Who conducted a study showing this issue and what did they do/find? Dement and Kleitman (1957) woke participants up when their brain waves were characteristic of REM sleep and found that they were highly likely to report dreaming. HOWEVER they also found dreams were recorded outside of REM and during REM they weren't always dreaming.
Why is the link between REM and dreaming important? It potentially provides a way to identify when a person is dreaming and also might provide theorists with a way to explain dreaming
What did Hobson and McCarley (1977) propose? that dreams are just a psychological readout of the random electrical signals typical of REM sleep.
What are theories like Hobson and McCarley based on? the assumption that REM sleep=dreaming.
What is another example of an ultradian rhythm? Basic rest-activity cycle
We have a 90 minute sleep cycle throughout the night so what does this suggest? That throughout the day there is also a 90 minute 'clock' ticking
Who researched and discovered this cycle? Friedman and Fisher (1967) who observed eating and drinking behaviour in a group of psychiatric patients over periods of 6 hours and found a clear 90-minute cycle in eating and drinking
What does the basic rest-activity cycle show? that sleep stages are part of a continuum - a 90-minute cycle that occurs throughout the day within the circadian rhythm
What is the importance of this 90-minute rhythm? probably a form of timing to ensure that the biological processes in the body work in unison
How long does an infradian rhythm last? greater than 24 hours but less that 1 year
What is an example of an infradian rhythm? The menstrual cycle
What is the function of the menstrual cycle? to regulate ovulation
Which hormones does the pituitary gland release? FSH (follicle stimulating hormone) and LH (luteinising hormone)
What do these hormones do? they stimulate a follicle in one ovary to ripen an egg and also triggers the release of the female hormone oestrogen.
What happens when the egg has ripened? the ruptured follicle starts to secret
What does progesterone do? causes the lining of the womb to prepare for pregnancy by increasing it's blood supply
What happens 2 weeks after ovulation if there is no pregnancy? progesterone is reduced which causes the lining of the womb to be shed (period)
Why is the menstrual cycle an infradian rhythm? It occurs once every month which means it is more than every 24 hours but less that 1 year
What is the monthly rhythm that affects males? temperature and alertness
Who conducted a study on this and what did they find? Empson (1977) studied 21 males and had their body temperature and alertness levels measured over periods varying from 49 - 102 days. They found some evidence for periodic variation of both body temperature and subjective ratings of morning alertness, with a cycle length of approximately 20 days.
Can the menstrual cycle be controlled by exogenous cues? Research shows that when several women live together and don't take oral contraceptives they tend to menstruate at the same time every month.
Who conducted a study to show this, what did they do and what did they find? Russell et al (1980) collected daily samples of sweat from one group of women and rubbed it on the upper lip of women in the second group. Although the groups were kept separate, their cycles synchronised with the women who's sweat they had on their lip.
What do the findings of Russell et al suggest? the synchronisation of menstrual cycles can be effected by pheromones - chemicals which are released in sweat for example. Pheromones act like hormones
What are the consequences of the menstrual cycle? Premenstrual syndrome (PMS) is a disorder that affects many women in the week leading up to menstruation (when progesterone is rising)
What are the symptoms of premenstrual syndrome? acne, anxiety, depression, food cravings, fatigue, headaches, insomnia, water retention, mood swings and aggression.
Why was PMS dismissed for many years and what do we know about it now? It was considered as being only a psychological problem but now we know that it is a physiological problem (with psychological symptoms) caused mainly by hormonal changes related to the infradian rhythm.
What did Dalton (1964) find? That PMS was also associated with an increase in accidents, lower achievement academically, suicides and crime
Name a second infradian rhythm Seasonal Affective Disorder (SAD)
Infradian rhythms don't always happen once a month, they can also happen... once a year
What is seasonal affective disorder? a depressive condition that some people suffer from during the winter months and they recover from during the summer.
Do we all get SAD? we all may experience some lowering of mood with more hours of darkness than sunlight however sufferers of SAD have much more severe symptoms.
What causes this depression? research studies show that the hormones melatonin and serotonin are secreted by the pineal gland when it is dark. In winter more darkness means more melatonin is released, more melatonin means more less serotonin (because melatonin is produced from serotonin). Low levels of serotonin are associated with depression.
What could SAD be a consequence of as opposed to being a natural outcome of infradian rhythms? A disrupted circadian rhythm. In the UK as the seasons change from summer to winter the circadian rhythm may be thrown out of phase. People often wake up at the same time but go to bed earlier as it is darker earlier. This means that the biological system gets the impression that time is shifting and the results can be similar to jet lag.
How does the research make up a deterministic approach Premenstrual syndrome (PMS) has been used in legal cases. Johnson (1987) - Ms English drove her car into her married lover, killing him. Charged with murder but put on probation because it was argued that her actions were related to severe PMS
Who was Katharina Dalton and what did she argue? She was a GP and pioneer researcher in PMS, she has acted as an expert witness and argued that severe PMS was akin to a mental disorder and therefore individuals should not be held responsible for their actions.
How is this deterministic? Shows that our biological rhythms may be beyond our control.
Is there research that contradicts this, if so by who and what did they do? Born et al (1999) who discovered that we can 'will' our biological rhythms to change. People who were told to wake up at earlier times of the night than usual had higher levels of ACTH (which contributes to the waking up process) than normal at the designated time and they woke up earlier.
Is there are Real World Application from this research? The understanding of darkness causing SAD has lead to affective therapies such as phototherapy which uses very strong lights in the evening and early morning to change levels of melatonin and serotonin.
What are the lights equivalent to? full daylight being between 6,000 and 10,000 Lux
What do SAD sufferers report after using this box? relieves them of their feelings or lethargy and depression
What is a criticism of this treatment? There could be a placebo effect, if people think that the light box will make them feel better then they will feel better.
Who conducted a study to prove this placebo effect? Eastman et al (1998) found that in a placebo condition (fake negative-ion) generator) it was less effective HOWEVER 32% of participants did improve with the placebo alone.
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