Biopsychology: Circadianrythmns

Question 1

What are biological rhythms

Answer 1

• distinct patterns of changes in body activity that conform to cyclical time periods
• influenced by internal body clocks (endogenous pacemakers) + external changes to the environment (exogenous zeitgebers)

Question 2

The sleep/wake cycle

Answer 2

• when we feel drowsy at night time and alert during the day is an example of the effect of daylight (exogenous zeitgeber) on the sleep/wake cycle
• researchers have conducted studies into what would happen if the biological clock was ‘left to its own devices’ + without external stimuli

Question 3

Outline ‘siffre’s cave study’

Answer 3

• has spent extended periods of time underground himself studying the effects of his biological rhythms
• deprived of natural light + sound he resurfaced in mid September in the caves of the southern alps believing it to be mid August
• each time his ‘free running’ biological rhythms settled to around 25 hours instead of 24

Question 4

Outline Aschoff and Wevers study

Answer 4

• convinced a group of ppts to spend 4 weeks in an WW2 bunker deprived of natural light
• all but one of the participants displayed a circadian rhythm between 24-25 hours
• suggest that the ‘natural’ sleep wake cycle may be slightly longer than 24 hours

Question 5

What study contradicts the findings in both siffre’s study and Aschoff and Wever’s

Answer 5

• Folkard et al studied 12 people who agreed to live in a dark cave for 3 weeks
• they would retire t bed when the clock said 11:45pm and rise when it said 7:45am
• unknown to the ppts, the researchers sped up the clock so an apparent 24 hour day only lasted 22 hours
• only 1 of the ppts was able to adjust to the new regime
• so a strong free running circadian rythmn cannot easily be overridden by changes in external environments

Question 6

What are the three evaluation Points for circadian rhythms

Answer 6

• practical application to shift work
• practical application to drug treatments
• use of case studies limits generalisability

Question 7

Outline ‘practical application to shift work’ as an evaluation point for circadian rhythms

Answer 7

• knowledge of circadian rythmns has helped researchers have a better understanding of the consequences that can occur as a result of their disruption
• e.g. night workers who engaged in shift work experience a period of reduced concentration around 6am (a circadian trough)
• so mistakes and accidents more likely at this time (Bolivian et al)
• shift workers are also 3x more likely to develop heart disease potentially because of the stress of adjusting to different sleep/wake patterns

Question 8

Outline ‘practical application to drug treatments ’ as an evaluation point for circadian rhythms

Answer 8

• circadian rhythms coordinate a number of the body’s basic processes (heart rate, digestion etc)
• which in turn has an effect on the action of drugs on the body and how well they are absorbed and redistributed
• circadian rhythm research has revealed peak times when drugs will be most effective

Question 9

Outline ‘use of case studies limits generalisability ’ as an evaluation point for circadian rhythms

Answer 9

• studies of sleep/wake cycle tend to involve small groups of ppts
• the people involved may not be representative of the wider population which limits generalisability
• e.g. in siffre’s most recent cave study he found, at the age of 60, his internal clock was much slower than when we was a young man

Question 10

What is a circadian rhythm

Answer 10

• a type of biological rhythm, subject to a 24 hour cycle,which regulates an number of body processes such as the sleep/wake cycle