Infradian and ultradian rhythms BP

Question 1

infradian rhythm

Answer 1

a type of biological rhythms with a frequency of less than one cycle in 24 hours, such as menstruation and seasonal affective disorder

Question 2

ultradian rhythm

Answer 2

a type of biological rhythm with a frequency of more than one cycle in 24 hours, such as the stages of sleep (the sleep cycle)

Question 3

What is the menstual cycle governed by?

Answer 3

monthly changes in hormone level with regulate ovulation

Question 4

what does a cycle refer to?

Answer 4

Cycle refers to the first day of a woman’s period (shedding the lining) to the day before her next period

Question 5

how many days is a typical cycle?

Answer 5

A cycle is typically 28 days but can be anywhere between 24-35 days

Question 6

What causes the egg to develop and release (ovulation)?

Answer 6

oestrogen

Question 7

What does progesterone do?

Answer 7

helps the womb lining grow back

Question 8

synchronising the menstual cycle

Answer 8

Despite the menstrual cycle being an endogenous system, evidence suggests that it could be influenced by exogenous factors like other women’s cycles

Question 9

Stern and McClinton’s pricedure

Answer 9

• Studied 29 women with irregular periods
• Gathered samples of pheromones from 9 women at different stages of their cycles via a cotton pad under their armpit
• Pads were worn for 8 hours then treated with alcohol and frozen
• Pads were rubbed on upper lip of the other participants
• On day 1 → pads from start if cycle were applied and so on

Question 10

Stern and McClinton’s findings

Answer 10

68% of women experienced changed in their cycle which brought them closer to their ‘odour donor’

Question 11

seasonal affective disorder

Answer 11

SAD is a depressive disorder with a seasonal pattern of onset and is part of DSM-5. Symptoms are triggered in winter months where days are shorter.

Question 12

symptoms of seasonal affective disorder SAD

Answer 12

• Persistent low mood
• General lack of activity and interest in life
• Change in weight

Question 13

What type of infradian rhythm is SAD?

Answer 13

circannual rhythm because it is on a yearly cycle. But it is also classed as a circadian rhythm as it could be experienced due to disruption of the sleep/wake cycle (darker longer in winter).

Question 14

What casues the secretion of melatonin from the pineal gland not stop in the morning?

Answer 14

During winter, the lack of light in the morning means the secretion of melatonin from the pineal gland doesn’t stop. This has an effect on the production of serotonin in the brain (linking to depressive symptoms).

Question 15

the stages of sleep

Answer 15

The stages of sleep (the sleep cycle) have been intensively researched. 5 stages have been identified that span about 90 minutes per cycle and each stage is characterised by a different brain wave that can be measured with an EEG.

Question 16

stage 1and 2

Answer 16

light sleep, easily woken, high frequency brainwaves and short amplitude (alpha waves), random changes in stage 2 called sleep spindles

Question 17

stage 3 and 4

Answer 17

deep sleep, slow wave sleep, delta waves, lower frequency and higher altitude, difficult to wake up, dreams can occur

Question 18

stage 5

Answer 18

paralysed body but brain remains active, theta waves, eyes occasionally move, rapid eye movement REM, dreams can occur

Question 19

infradian rhythms strength

I

Answer 19

Evolutionary basis
May be explained by natural selection

Question 20

infradian rhythms strength

D

Answer 20

• Stern and McClinton’s research on synchronisation may have evolutionary value
• Ancestors may have found it convenient to menstruate together and fall pregnant at the same time
• Babies who had lost their mothers could then still access breast milk which increases their chance of survival

Question 21

infradian rhythms strength

E

Answer 21

Synchronisation is an adaptive strategy

Question 22

infradian rhythms limitation

I

Answer 22

Methodological shortcomings

Question 23

infradian rhythms limitation

D

Answer 23

• Many factors could affect menstrual cycle eg stress, diet, exercise
• Confounding variables means that synchronisation could have just occurred by chance as explained by Trevathan et al

Question 24

infradian rhythms limitation

E

Answer 24

Menstrual synchrony studies are flawed

Question 25

infradian rhythms RWA

Answer 25

Light therapy is one of the most effective treatments for seasonal affective disorder, where a light is used to reset someone’s body clock. Sanassi found that it helped 80% of people.

Question 26

ultraradian rhythms strength

I

Answer 26

Improved understanding of age-related changes in sleep

Question 27

ultraradian rhythms strength

D

Answer 27

• SWS reduces with age
• Growth hormone is reduced in old age as a result of this
• Cauter et al found that this sleep deficit may explain various issues in old age eg reduced alertness
• Relaxation and medication can be used to increase SWS

Question 28

ultraradian rhythms strength

E

Answer 28

Knowledge of ultradian rhythms has practical value

Question 29

Ultradian rythms limitation

I

Answer 29

Significant variation between people

Question 30

Ultradian rythms limitation

D

Answer 30

• Tucker et al found large differences between participants in terms of duration of each sleep stage, mainly 3 and 4
• These differences are biologically determined

Question 31

Ultradian rythms limitation

E

Answer 31

Difficult to describe ‘normal sleep’ in a meaningful way

Question 32

Dement and Kleitman

Answer 32

• First to use EEG to identity the stages of sleep
• They would wake them up periodically and ask them what they had just been experiencing
• If they were woken up during stages 1-4 they would report nothing but if woken up during REM they would report dreaming
• Thus suggesting that there are 90 minute cycles and not one continuous dream