Circadian Rhythms

Question 1

What is a biological rhythm + what are they influenced by?

Answer 1

Distinct patterns of changes in the body activity that conforms to cyclical time periods. Biological rhythms are influenced by internal body clocks and external changes to the environment

Question 2

What is a circadian rhythm?

Answer 2

24 hour cycle, such as sleep-wake cycle and change in body temperature

Question 3

What is the body internal body clock called?

Answer 3

Endogenous pace maker

Question 4

What is the sleep/wake cycle governed by?

Answer 4

• Suprachiasmatic nucleus, which lies above optic chiasm providing info from eye about light.
• If left to our own devices we become free running

Question 5

What happened in Siffres Cave study

Answer 5

• He studies biological rhythms while deprived of natural sound and light
• He essentially “free ran” with his biological clock extending to 25+ hours rather than the original 24
• He came out when it was mid-august yet it was mid September

Question 6

Other supporting research?

Answer 6

• Aschoff and Wever: participants spent four weeks in a world war 2 bunker deprived of natural light, most cycles between 24-25 hours, natural cycle slightly longer than 24
• Folfkard et al studied 3 people living in dark cave for three weeks they set a clock which slowly speeded up to 22 hour cycle only one participant could keep up with. Strong free running circadian rhythm cannot be easily overridden by exogenous zeitgebers

Question 7

What are the AO3 point? (brief)

Answer 7

• Understanding of adverse consequences of desynchronisation: SHIFT WORK HOWEVER, use correlational methods may not be biological factors
• Used to improve medical treatment
• Generalisations are difficult to make, individual issues

Question 8

What are strengths of circadian rhythm?

Answer 8

• Understanding of shift work, consequences when they’re disrupted. Reduced concentration at 6am (circadian trough) mistakes are more likely. Relationship between shift work and poor health, more likely to develop heart disease. Economic implications, manage worker productivity. HOWEVER, difficult to establish whether desynchronisation is actually the cause of negative effects may be other things such as high divorce rates. May not be biological factors causing adverse consequences.

Used to improve medical treatments, circadian rhythms co-ordinate a number of the body’s basic processes such as heart rate, digestion and hormone levels. Leading to the field of chronotherapeutics corresponding to biological rhythms. For example timing of aspirin to reduce heart attacks which usually happen in morning. Effectiveness of drug treatments

Question 9

What are the weaknesses of research into CR?

Answer 9

Generalisations are difficult to make, based on small number of px’s sleep/wake cycles may vary person to person from 13-65 hours. Some people have a natural preference for getting up early whereas others prefer the opposite. Siffres own sleep cycle slowed as he became older. Difficult to use research data to discuss anything more than averages which may be meaningless.