Biopsychology: Biological Rhythms

Question 1

The 3 different types of biological rhythms are …

What is a biological rhythm?

Answer 1

Ultradian
Circadian
Infradian

a distinct pattern of changes in the body activity that relates to cyclical time periods

Question 2

Give the duration of each of the three biological rhythms

What 2 things keep our biological rhythms in sync ?

Answer 2

Ultradian-less than 24 hours
Circadian-approxiametly 24 hours
Infradian-more than 24 hours

endogenous pacemakers and exogenous zeitgebers

Question 3

Endogenous pacemakers are our ..

Exogenous zeitgebers are …

Answer 3

body’s internal body clocks

external changes in the environment that reset our biological clocks

Question 4

Give an example of an ultradian biological rhythm

Answer 4

stages of sleep

Question 5

How are the stages of sleep monitored and what does monitoring show about the different stages of sleep?

How many stages are involved in the sleep cycle?
How long does each stage of the cycle usually last?

Answer 5

monitored using an EEG
the monitoring shows clear differences in the brains activity during the different stages of sleep

there are 5 stages
approx 90 minutes

Question 6

Name the 5 stages of the sleep cycle … 1+2 are the same and 3+4 are the same

Answer 6

1+2 = light NREM sleep
3+4 = slow wave NREM
5 = REM sleep

Question 7

Who provides research support for ultradian rhythms?
Describe this research and what it suggests about the sleep stage cycle?

Answer 7

Dement and Kleitman (1957) - monitored sleep patterns of 6 ppts in a sleep lab and activity recorded using an EEG
they found REM activity was highly correlated with experience of dreaming and replications of the study have found similar findings

the consistency of timings of the sleep wake stage between ppts suggests the cycle is controlled by endogenous pacemakers

Question 8

Give an example of a circadian rhythm

The control of this cycle relies on the interaction of what 2 things?

Answer 8

the sleep wake cycle

endogenous pacemakers and exogenous zeitgebers

Question 9

Name the 3 structures of the body that act as endogenous pacemakers in the sleep wake cycle , describe their roles

Answer 9

Suprachiasmatic nucleus (SCN) - is a bundle of fibres in the hypothalamus
its connected to the visual area and receives info about light

Pineal gland-receives info from the SCN and releases melatonin which induces sleep

Adrenal gland-releases cortisol which induces wakefulness

Question 10

What 2 things act as exogenous zeitgebers in the sleep wake cycle , describe their effect on the cycle

Answer 10

Light- is key in providing info for the SCN
when its dark , SCN signals pineal gland to release melatonin and when its light it signals the pineal gland to stop producing melatonin

Social cues- includes meal times . exercise , regularly timed social interactions

Question 11

Who provides research support for endogenous pacemakers and exogenous zeitgebers ?

Describe this research and what it suggests …

Answer 11

DeCoursey et al (2000) - destroyed SCN connections of 30 chipmunks who were then returned to natural habitat for 80 days

found that their sleep wake cycle disappeared and a significant portion were killed by predators as without SCN connections they couldn’t receive or project info about light
suggests endogenous pacemakers aren’t only system involved in the cycle , and that light as an ExZ is essential for maintaining the cycle

Question 12

Who else provides research support for EnP and ExZ ?

Describe this study and what it suggests …

Answer 12

Kleitman and Richardson (1938) - spent 32 days in Mammoth Cave where there was no detectable light

Richardson developed a sleep wake cycle of 26-28 hours and Kleitman’s was just over 24 hours , showing the both maintained a endogenous rhythm but both were inconsistent with the normal 24 hour cycle when exposed to light

this suggests sunlight entrains a persons body clock to 24 hours , so acts as an exogenous zeitgeber

Question 13

Give an example of an infradian rhythm

What is this rhythm controlled by ?

Answer 13

the menstrual cycle

controlled by changes in hormone levels which regulate ovulation

Question 14

Who provides research support for infradian rhythms?

Describe this study and what it suggests …

Answer 14

Stern and McClintock (1998) - demonstrated how exogenous zeitgebers such as pheromones of other women can influence a woman’s cycle

pheromone samples were taken from 9 women and treated , then given to other ppts by rubbing them on the upper lip

they found 68% ppts experienced changes that brought them closer to their ‘odour donor’ which shows that exogenous factors can influence an infradian cycle

Question 15

Evaluate the strengths of research into biological rhythms …

There are 2

Answer 15

+ there is lots of research evidence that can be used to support the different types of biological rhythm , suggesting they are an actual concept

+ positive implications of research , knowledge of circadian rhythms has been useful in explaining the negative effects of desynchronisation , such as in shift workers who have been found to be at higher risk of heart disease and anxiety , therefore allowing changes to be made to benefit workers

Question 16

Evaluate the weaknesses of research into biological rhythms …

There are 2

Answer 16

-generalisations and small samples , research often uses very small samples that may not represent the wider population which limits the ability to generalise research

additionally the use of animal research in DeCoursey et al study has been criticised as its not highly valid to generalise findings from animals to humans

-poor control, eg in Kleitman and Richardson’s study extraneous variables were not controlled as they still has access to food and social interactions which act as exogenous zeitgebers so we can’t conclude that the sleep wake cycle is just endogenously controlled