Effects if endogenous Pacemakers & Exogenous Pacemakers - 16m Flashcards
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Research to support the role of endogenous pacemakers on the sleep wake cycle was conducted by Michel Siffre (1975). He lived in a cave isolated from all exogenous zeitgebers e.g. clocks and the light dark cycle for six months. It was found that within a few days he had developed a consistent 25 hour cycle and continued to fall asleep and wake up on a regular schedule.
This suggests that the sleep wake cycle is controlled by an endogenous
Cacemaker. This supports the theory that the sleep wake cycle is primarily governed by endogenous pacemakers rather than exogenous zeitgebers.
DISCUSSION: However, some may argue that because Siffre’s sleep wake cycle did adjust to longer than 24 hours, that exogenous factors are important in maintaining the sleep wake cycle.
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However, research, such as Siffre’s, lacks ecological validity as they are highly controlled and do not reflect how endogenous pacemakers and exogenous zeitgebers interact in real life. Only in exceptional circumstances are endogenous pacemakers free-running and unaffected by the influence of exogenous zeitgebers. In real-life, pacemakers and zeitgebers work together and it makes little sense to separate the two for the purpose of research. Therefore, this reduces the external validity of the findings and cannot be generalised to explain how endogenous pacemakers impact the sleep wake cycle in real life.
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However, research investigating the impact of endogenous pacemakers on the sleep sake cycle can be criticised for animal bias. This is potentially a problem because humans may nave more complex biological rhythms to animals as they have higher mental functioning.
Therefore, there are issues with extrapolating the findings of the research to humans, which limits the extent to which DeCoursey’s findings support the importance of endogenous pacemakers on the sleep wake cycle.
