Bio Rhythms: Circadian Rhythms Flashcards
What is a biological rhythm?
A distinct patterns of changes in a body activity that conform to cyclical time periods, they are influenced by body clocks and external changes to the environment
Who are subject to biological rhythms?
All living organisms
What governs biological rhythms?
Internal body clocks - endogenous pacemakers and external changes in the environment - exogenous zeitgebers
What are circadian rhythms?
A type of biological rhythm, subject to a 24 hour cycle, which regulates a number of body processes such as the sleep/wake cycle and changes in core body temperature
How do internal and external factors influence the sleep wake cycle?
Light acts as an exogenous zeitgeber - making us feel drowsy at night and alert in the day
What if the internal body clock was left to ‘free-run’ would we still wake up at regular intervals
Outline the aim, procedure and findings from Siffre’s cave study
What would happen if our biological clocks were left to their own devices (No clocks or light) - would we still wake up and sleep at regular times? Siffre spent extended periods of time underground deprived of natural light -1962 Alps, 1972 Texas. In each case his biological rhythm settled down to one that was just beyond 24 hours (around 25 hours)
Outline 2 pieces of research into circadian rhythms
Ashoff and Wever (1976) participants were placed in a world war ll bunker without natural light. All but one participant displayed a circadian rhythm of 24-25 hour. This suggests the natural sleep/wake cycle is slightly longer than 24 hours but is entrained by external factors.
BUT;
Simon Folkard et al. (1985) –12 ppl lived in a cave for 3 weeks they went to bed at 11 :45 and were up at 7 :45 –researchers sped up the clock so days were actually 22h long. Only 1 pcp could comfortably adjust –shows internal body clocks are hard to overcome/influence.
Outline 2 practical applications of research into circadian rhythms (Eval +)
Shift work - Research has shown that night workers are likely to experience a loss of concentration around 6 am (Boivin at al). Late shift workers are more likely to experience heart disease, possibly due to the stress of having to adjust to poor sleep quality and an unusual sleep pattern.
Drug treatments - Circadian rhythm coordinate basic processes in the body - pharmacokinetics (the actions of drugs on the body). Research into circadian rhythms has revealed when drugs are likely to be most effective.
Outline two possible reasons why the result of research into circadian rhythms lacks generalisability (Eval -)
Uses of case studies and small samples, e.g. Siffre. He was over 60 - he noticed that as he got older his circadian rhythm slowed.
Individual differences -Some cycles vary between 13 and 65 hours in some cases (Czeisler et al). Some people like to go to bed early and rise early and some do the opposite.
