Infradian and ultradian rhythms - AO1

Question 1

What is infradian rhythms and what are examples

Answer 1

Duration of longer than 24 hours

• Menstrual cycle
• Seasonal affective disorder

Question 2

What is the menstrual cycle?

Answer 2

• Monthly (28 days) hormone changes
• Rising oestrogen causes ovulation, then progesterone causes lining to thicken
• No fertilisation = lining sheds - menstrual slow
• Cycle begins again

Question 3

What did Stern and McClintock (1998) do?

Answer 3

• 29 women, sweat samples from nine applied to other’s upper lips
• 68% experienced cycle synchronisation with their “odour donor”
• Shows exogenous zeitgeber of pheromones influencing otherwise endogenous cycle

Question 4

What is seasonal affective disorder?

Answer 4

• DSM-5: form of depression that follows a yearly cycle
• Linked to reduced light in winter = higher melatonin
• Pineal gland uses serotonin to synthesise melatonin
• Leads to reduced serotonin

Question 5

What is ultradian rhythm and what are examples?

Answer 5

Duration less than 24 hours

• E.g stages of sleep

Question 6

What are the stages of sleep (definition)

Answer 6

Occur in 90 min cycles of five distinct stages characterised by a different level of brainwave activity

Question 7

What is stage 1+2 of the sleep cycle?

Answer 7

Light sleep
Alpha waves, high frequency and short amplitude
Occassional sleep spindles

Question 8

What is stage 3+4 of sleep cycle?

Answer 8

Deep sleep (slow wave sleep)
Delta waves, lower frequency and high amplitude

Question 9

What is stage 5 of the sleep cycle?

Answer 9

REM (rapid eye movement)
Theta waves
Closely resemble the awake brain
Body is paralysed
Marks the end of the natural cycle which will either begin again or cause waking