infradian rhythms

Question 1

how is SAD a type of infradian rhythm?

Answer 1

• subject to yearly cycle
• depressive disorder triggered by seasonal changes
• casued by less sunlight and shorter days disrupting bodys internal clock

Question 2

why is SAD more prevalent in winter?

Answer 2

• changes in season disrupts body’s melatonin. longer nights increases melatonin
• reduced serotonin= depressive symptoms due to reduce sunlight

Question 3

symptoms of SAD and how to treat?

Answer 3

• loss interest, low energy, sleeping problems, weight gain
• treat through light therapy

Question 4

how is the menstrual cycle an infradian cycle?

Answer 4

• its controlled by monthly changes in hormone levels which regulate ovulation
• typical cycle lasts 28 days

Question 5

what happens at ovulation?

Answer 5

rising level of oestrogen causes development and release of egg

Question 6

what happens after ovulation?

Answer 6

progesterone helps uterus lining grow thicker to ready body for pregnancy

Question 7

what happens after uterus lining gets thicker?

Answer 7

if fertilisation doesnt occur then the egg and lining of the uterus leaves the body

Question 8

what research support is there for the menstrual cycle?

Answer 8

Stern and McClintock
- menstrual cycles may synchronise as a result of female pheromones
- 29 women with irregular periods where pheromones collected from airpits using cotton pad at diff stages of periods
- rubbed on upper lip of other women
- 68% of women experienced changes to their cycle

Question 9

what does the research support suggest about EPs and EZs?

Answer 9

• EPs have influence on mestrual cycle as it is governed by hormones
• EZs of other women can affect other womens cycles

Question 10

what are problems with the research support for menstrual cycles?

Answer 10

• unrealiable- other researchers havent done same/ found same results
• unethical
• small smaple- 29 women
• EVs- birth control, stress, diet affect period

Question 11

how can menstrual synchrony be explained from an evolutionary perspective?

Answer 11

• for our ancestors might have been useful for females in same tribe to menstruate together and become pregnant at same time
• means new borns could be cared for collectively, increasing chance of offspring survival
• counter-> methodological issues + cofounding variables eg stress, changes in diet. means synchronised patterns would have been expected to happened, questions reliablity.

Question 12

what practical applications do infradian rhythms have?

Answer 12

• phototherapy has been developed as effective treatment for SAD
• lightbox stimulating strong light in morning and evening- resets melatonin levels of ppl with SAD
• reduces symptoms upto 60%
• counter-> can produce headaches + eye strain. Rohan- relapse rate of 46% over winters, 27% with CBT
• therefore, phototherapy less successful than other treatments as is short term