3.9. Circadian Rhythms

Question 1

What are circadian rhythms?

Answer 1

Biological rhythms that change bodily activity to conform to a cyclical time period

Question 2

What are circadian rhythms regulated by?

Answer 2

Endogenous and exogenous pacemakers

Question 3

What does every cell contain?

Answer 3

A clock that’s synchronised by the Superchiasmatic Nuclei in the hypothalamus

Question 4

What is the sleep-wake cycle?

Answer 4

We feel drowsy at night and alert during the day- due to light (exogenous pacemaker) -> light resets the SCN

Endogenous and Exogenous work together to keep this in time

Question 5

Case study 1: Siffre

Answer 5

• Siffre spent extended periods in a cage (2 months and 6 months) to study effects in endogenous pace makers -> he was deprived of sunlight and noise
• He found that his free running rhythm is 25 hours, not 24
• His sleep stayed regular (8 hrs)
• Endogenous pacemakers significantly influence biological rhythms

Question 6

Case study 2: Folkard

Answer 6

• 12 ppts lived in a cave for 3 weeks, going to sleep at 11:45 pm and woken at 7:45 am
• Unknown to them, researchers sped up the clock to 27 hr days -> only 1 person adapted to this
• Suggests free running biological rhythms cannot be overridden to changes in environment

Question 7

Weakness: generalisation

Answer 7

Case study hard to generalise due to individual differences

Question 8

Weakness: age

Answer 8

Age may have been a factor, as a result be limited to similar age groups

Question 9

Weakness: other variables

Answer 9

Other variables such as air temp, pressure and monitoring equipment could affect the results and decrease validityS

Question 10

Strength: real world application

Answer 10

Shift work has been found to lead to desynchronisation of circadian rhythms, leading to physiological and psychological health issues

Bovin: night shift workers experience a lapse in concentration around 6am (leading to accidents)

A relationship has been found between night shift workers and poor health leading to heart disease due to adapting to different sleep/wale patterns

Question 11

Strength: economic implications

Answer 11

Led to the development of night shift schedules e.g. 4 nights on 4 nights off

Question 12

Strength: RWA development of…

Answer 12

Led to the development of chronotherapy -> study of how timings affect drug treatment (as rhythms affect digestion)

Aspirin should be taken at 10pm to thin blood so you don’t have a heart attack at 4am