Biological rhythms: circadian rhythms

Question 1

What are biological rhythms?

Answer 1

• pattern of changes in the body that follow cyclical time periods
• influenced by internal body clocks
• influenced by environmental changes

Question 2

What are endogenous pacemakers?

Answer 2

• the bodys internal biological body clocks

Question 3

What are exogenous zeitgerbers?

Answer 3

• external changes to the environment

Question 4

What are circadian rhythms?

Answer 4

• rhythms that last around 24 hours
• sleep/wake cycle
• core body temperature

Question 5

what is the suprachiasmatic nucleus (SCN)?

Answer 5

• endogenous pacemaker that governs the bodys sleep/wake cycle as it is a biological clock
• lies above the optic chasm and provides info from the eye about light
• exogenous zeitgerber (light) can reset the SCN

Question 6

Siffre’s cave study (1962)

Answer 6

• spent several extended periods underground to see the effect on his biological rhythm
• surfaced in mid-sept after two months but thought it was mid-aug

Question 7

Siffre’s second cave study: texan cave

Answer 7

• spent 6 months in a texan cave
• his ‘free running’ biological rhythms settled to 25 hours but with falling asleep and waking up on a regular schedule

Question 8

Aschoff and wever: WW2 bunker research

Answer 8

• convinced pp to spend 4 weeks in bunker deprived of natural light
• all but one participants had circadian rhythms of 24 or 25 hours
• suggested the natural sleep/wake cycle lasted slight longer than 24 hours but was entrained by exogenous zeitgerbers of a 24 hour day

Question 8

Folkard (1985): dark cave study

Answer 8

• 12 people lived in a dark cave for three weeks
• going to bed when clock said 11:45 and waking up when the clock said 7:45
• they gradually sped up the clock so 24 hours was actually just 22
• one pp could adjust
• strong circadian rhythm cant be over ridden by exogenous zeitgerbers

Question 8

Evaluation limitation: counterpoint to shift work (correlational)

Answer 8

• studies use correlational methods
• other factors may cause desynchronisation
• solomon found high divorce rates could be due to less sleep and missing out on family events
• biological factors may not cause consequences associated with shift work

Question 8

Evaluation strength: shift work

Answer 8

• able to understand consequences of disrupted circadian rhythms
• night shift workers have reduced concentration at around 6 am = mistakes
• shift workers have poorer health
• helps manage worker productivity

Question 8

Evaluation strength: medical treatment

Answer 8

• coordinate many bodily processes e.g. hormone levels HR and digestion
• these rise and fall so there has been resreach into how medicine can be administered to fit someones biological rhythm e.g. aspirin
• help increase effectiveness of drug treatments

Question 8

Evaluation limitation: individual differences

Answer 8

• hard to make generalisations
• studies were done on small samples
• found sleep/wake cycles can vary from 13-65 hours
• Duffy et al. found people have natural preference for waking or sleeping early
• hard to use data to discuss anything more than averages