Infradian and Ultradian Rhythm

Question 1

The Menstrual cycle as an Infradian Rhythm?

Answer 1

• governed by monthly changes in hormone levels that regulate ovulation. First day-womb lining shed. Lasts 28 days
• rising levels of oestrogen cause ovary to develop egg and release it, post ovulation progesterone helps womb lining thicken
• if pregnancy does not occur, egg is absorbed, womb lining comes away and leaves the body

Question 2

Who studied the synchronisation of the menstrual cycle?

Answer 2

• although endogenous system, may be influenced by exogenous factors. Stern and Mcclintock pheromones:
• 29 women with irregular periods, pheromone samples were were taken from 9 women at different stages via cotton pad in armpit for 8 hours. treated with alcohol and frozen. rubbed on upper lips of other pps, on day 1 of cycle pads were applied to 20 women, day 2 given pad from second day and so forth
• 68% experienced changes to their cycle

Question 3

Seasonal Affective Disorder as an Infradian rhythm?

Answer 3

• SAD: general symptoms are lowered mood, lack of activity/interest in life. Due to daylight hours becoming shorter (circannual rhythm - yearly cycle)
• can also be classed as circadian as may be caused by disruption to the sleep wake cycle
• hormone melatonin causes SAD, regularly pineal gland secretes melatonin when dark, lack of light in mornings during winter mean secretion process is elongated - knock on effect with serotonin (linked to depressive symptoms)

Question 4

The sleep/wake cycle as an ultradian rhythm and how it is monitored?

Answer 4

• identified 5 distinct stages of sleep that span 90 mins approx and then repeats
• each of the stages are characterised by brain wave activity which are monitored using an EEG

Question 5

What are the five stages of sleep?

Answer 5

Stage 1/2: ‘light sleep’ high frequency short amplitude waves (alpha waves) - stage 2 same but with ‘sleep spindles’ (random changes in pattern)
Stage 3/4; ‘deep sleep’ low frequency high amplitude (delta waves
Stage 5: REM (rapid eye movement) sleep - body is paralysed yet brain activity resembles that of someone awake, theta waves, when dreams mostly occur

Question 6

What is one strength of research into menstrual cycles?

Answer 6

• On an evolutionary basis, may have been helpful to distant ancestors as if women become pregnant at the same time as babies without a mother would have access to breast milk, improving survival

Question 7

What is one limitation into research into menstrual cycle?

Answer 7

• endless confounding variables, no cause effect relationship as could have been diet, stress levels, exercise levels - flawed/invalid studies

Question 8

What is one strength of research into Ultradian rhythms?

Answer 8

• improved understanding of age related changes in sleep, Slow wave sleep reduces with age, growth hormone is mainly produced during SWS and so is reduced also. Cauter related this to issues experienced in old age e.g lack of alertness - in order to increase SWS medication and relaxation techniques can be used (practical value)

Question 9

What is one limitation of research into Ultradian rhythms?

Answer 9

• significant variation between people, Tucker found large differences between pps in terms of duration of each sleep stage particularly 3/4 which are biologically determined (according to Tucker) makes it difficult to describe normal sleep in a meaningful way

Question 10

Which is long and which is short?

Answer 10

• Infradian Rhythm are longer than 24 hours
• Ultradian Rhythms are shorter than 24 hours