Infradian + Ultradian

Question 1

What are Infradian rhythms and examples?

Answer 1

Biological rhythms with a frequency of less than one cycle in a 24 hour period e.g. menstrual cycle & seasonal affective disorder

Question 2

What is the menstrual cycle?

Answer 2

• it is governed by monthly changes in hormone levels which regulate ovulation
• cycle refers to the first day of a women’s period to the day before her next period
• cycle takes approximately 28 days to complete

Question 3

What happens during the menstrual cycle? endogenous systems

Answer 3

• increased oestrogen levels cause ovary to develop an egg and release it
• after ovulation increased progesterone levels help the womb lining to grow thicker- preparation for pregnancy
• if pregnancy does not occur the egg is absorbed into the body, the womb lining sheds away and leaves the body (menstrual flow

Question 4

Outline research and findings of study that shows that the menstrual cycle may be influenced by exogeneous factors

Answer 4

• Stern & McClintock - menstrual cycle may synchronise through influence of pheromones
• samples of pheromones gathered from p’s at different stages of menstrual cycle via a cotton pad placed in armpit (8 hours)
• pads treated with alcohol & frozen then rubbed on upper lip of other pp’s
• 68% of women experienced changes to their cycle

Question 5

What is seasonal affective disorder and its symptoms?

Answer 5

• SAD is a depressive disorder which has a seasonal pattern of onset
• SAD is a particular type of infradian rhythm called circannual rhythm -subject to yearly cycle (winter seasons)
• main symptoms= low mood, lack of activity & interest in life

Question 6

Why is SAD often referred to as the ‘winter blues’?

Answer 6

symptoms are triggered during winter months, when daylight hours becomes shorter

Question 7

What is the endogenous pacemaker for SAD?

Answer 7

• endogenous pacemaker= melatonin
• during winter, lack of light in morning =secretion of melatonin longer
• has a knock on effect on production of serotonin -linked to depressive symptoms

Question 8

What is a limitation of research studies menstrual cycle (Stern & McClintock)?

Answer 8

• study could have been subject to confounding variables
• other factors that may have influenced the women’s menstrual cycles (stress, diet, exercise)
• Also relied on women self reporting the onset & duration of their cycles
• low internal validity

Question 9

What is a strength of menstrual synchrony research?

Answer 9

• can be explained by natural selection
• Stern and McClintock’s study > said to have some evolutionary value
• for ancestors it may have been advantageous for women to menstruate together & get pregnant at the same time
• new babies would be part of a social group who cared for one another & had access to breast milk if mother died at birth» improving their chances of survival

Question 10

What are ultradian rhythms and example?

Answer 10

A biological rhythm that has a cycle of more than once in a 24 hour period such as the stages of sleep

Question 11

What are the stages of sleep?

Answer 11

• Psychologist have identified five distinct stages of sleep that span together approximately 90 minutes
• each stage is characterized by different level of brain wave activity

Question 12

Describe stage 1 and 2

Answer 12

• Light sleep
• stage 1- brain waves have high frequency and low amplitude (alpha waves)
• stage 2 - alpha waves continue but their are random changes in patterns called spindle fibres

Question 13

Describe stage 3 and 4

Answer 13

• deep sleep
• brain waves are delta waves with low frequency and high amplitude

Question 14

Describe stage 5 (REM sleep)

Answer 14

• brain is paralysed
  brain produces theta waves
• eyes occasionally move around (REM)

Question 15

What is a strength of research into ultradian rhythms?

Answer 15

• improved understanding of age-related changes in sleep
• sleep scientists have observed that SWS (3 & 4) reduces with age
• Cauter et al- the resulting sleep deficit may explain various issues in old age such as reduced alertness
• To increase SWS medication may be used

Question 16

What is a limitation of Ultradian rhythms?

Answer 16

• One limitation of ultradian rhythms research is there is significant variation
  between people.
  -Tucker et al. (2007) found large differences between participants in terms
  of the duration of each sleep stage
  particularly stages 3 and 4.
  Tucker et al. suggest that these differences are likely to be biologically
  determined.
• This makes it difficult to describe ‘normal sleep’ in any meaningful way.

Question 17

What is another strength of research into ultradian rhythms?

Answer 17

• One of the benefits of conducting in lab settings (e.g. e Tucker et al. study), is the control of extraneous variables.
• This means that a researcher can exclude temporary variables such as noise or temperature that may affect sleep.
• This ensures that internal validity within such studies is high enabling us to be more confident to establish cause and effect.
• increased validity of research

Question 18

What is a counterpoint to Tuckers research?

Answer 18

Counter:
- However, lab studies involve being attached to complicated machinery.
- This may be invasive for the participants, leading them to sleep in a way that does not represent their ordinary sleep patterns.
- So, the data obtained from controlled lab studies may lack external validity when compared to sleep in an everyday context.
- This dilemma means it might be best to conduct some studies in people’s own homes and compare patterns with recordings made in lab settings