Infradian + Ultradian Rhythms

Question 1

What are ultradian rhythms?

Answer 1

-have a duration of less than 24 hours
-more than one cycle every 24hrs

Question 2

What are the stages of sleep?

Answer 2

-have identified 5 distinct stages of sleep that altogether spans over 90 minutes
-continues throughout the night
-each stage is characterised by a different brainwave that can be monitored via ECG

Question 3

What is stage 1 + 2 of the sleep cycle?

Answer 3

-light sleep
-where a person is easily woken
-stage 1 - brains waves = high frequency + short amplitude (alpha waves)
-stage 2 - alpha waves continue - occasional random changes in pattern = sleep spindles

Question 4

What are stages 3 + 4 of the sleep cycle?

Answer 4

-deep sleep
Or slow wave sleep
-brain waves = delta
-lower frequency + higher amplitude
-hard to wake someone up

Question 5

What is stage 5 of the sleep cycle?

Answer 5

-REM sleep
-body is paralysed but brain activity resembles usual awake brain
-brain produces theta waves
-eyes occasionally move around (rapid eye movement)
-dreams usually occur in REM but also deep sleep

Question 6

What is the basic rest activity cycle?

Answer 6

-Kleitman - referred to the 90 minute cycle found during sleep as BRAC - continues whilst we are awake
-instead of moving through stages of sleep, we move through alertness
-towards the end of fatigue - lose resources + concentration
-obvious in the way our days are ordinarily fragmented

Question 7

What is the infradian rhythm?

Answer 7

-type of biological cycle
-frequency of less than 1 cycle in 24 hours

Question 8

Is the menstrual cycle endogenous or exogenous?

Answer 8

-endogenous cycle

Question 9

When does the menstrual cycle begin?

Answer 9

-the first day is when the womb is shred to when day before next period
-28 day s

Question 10

What is the menstrual cycle controlled by?

Answer 10

-controlled by changes in hormone levels
-rising levels of oestrogen = ovulation
-progesterone helps womb lining to thicken

Question 11

What is synchronisation?

Answer 11

-evidence to show it may be influenced by exogenous factors
-eg. Cycles of other women
-Stern + McClintock

Question 12

What was Stern + McClintock’s study?

Answer 12

-studied 29 women with irregular periods
-samples of pheromones from 9 women at different stages - wore cotton pads under the armpits for 8 hours
-treated + given to other P’s by rubbing the pad on the upper lip
-found that 68% experienced changes to their cycle

Question 13

What is SAD?

Answer 13

-depressive disorder which has a seasonal pattern
-main symptom = persistent low mood + apathy

Question 14

Is SAD infradian or ultradian?

Answer 14

-infradian

Question 15

Seasonal affective disorder

Answer 15

-circannual rhythm
-subject to a yearly cycle
-due to disruption of the sleep/wake cycle
-attributed to prolonged periods of daily darkness during winter

Question 16

How does melatonin implicate the cause of SAD?

Answer 16

-during the night - pineal gland secretes melanin until dawn when there is light
-during winter = lack of light in morning - secretion process continues for longer
-may have a knock on effect on the production of serotonin in the brain

Question 17

What is one strength of synchronisation?

Answer 17

-may be explained by natural explanation
-thought to have some evolutionary value
-distant ancestors - advantageous to menstruate together + become pregnant at the same time
-in a social group - allows babies who had lost their mothers to access breast milk
-improving their chances of survival
-suggests synchronisation is an adaptive strategy

Question 18

What is a limitation of synchronisation?

Answer 18

-methodological shortcomings
-may factors effect change to the menstrual cycle: stress, diet + exercise
-act as confounding variables - any supposed pattern is no more than would have been expected to occur by chance
-may explain why other studies have failed to replicate the findings

Question 19

What is a practical application of SAD?

Answer 19

-most effective treatments for SAD = light therapy
-box that stimulates strong light to reset the body’s internal clock
-shown to h help reduce the effects of SAD in 80%
-preferred over antidepressants as it is regarded as self
-however it can produce headaches + eye strain

Question 20

What is a strength into research into ultradian rhythms?

Answer 20

-improved understanding of age related changes in sleep
-sleep scientists observed that SWS reduces with age
-growth hormone mostly produce during SWS = reduced in older
-Cauter - resulting sleep deficit may explain various issues in old age (reduced alertness)
-in order to increase SWS - relaxation + medication
-suggests that knowledge of ultradian has practical value