Endogenous pacemakers & exogenous zeitgebers

what are endogenous pacemakers

Internal body clocks that regulate many of our biological rhythms

what are exogenous zeitgebers

External factors that affect our biological rhythms

explain the strength research support for the role of exogenous zeitgebers on the sleep/wake cycle

Siffre found that the absence of external cues significantly altered his circadian rhythm. When he returned from an underground stay with no clocks or light, he believed the date to be a month earlier than it was. This suggests that his 24-hour sleep-wake cycle was increased by the lack of external cues. Other investigations, along with Siffre’s findings, suggest that humans use natural light (exogenous zeitgebers) to regulate a 24-hour circadian sleep-wake cycle, demonstrating the importance of light for this circadian rhythm

explain the strength research support for the role of endogenous pacemakers on the sleep/wake cycle

a researcher destroyed the SCN of chipmunks who were returned to their natural habitat & observed for 80 days. Sleep wake cycle disappeared over duration of study and high proportion killed by predators because awake and vulnerable when should have been asleep

explain the weakness pacemakers and zeitgebers cannot be studied in solation

in everyday life pacemakers & zeitgebers interact working together to maintain & control biological rhythms - it makes little sense to separate the two for the purpose of research and it is hard to separate their influence

explain the weakness research ignores the individual differences

research makes general conclusions about the effect of endogenous pacemakers & exogenous zeitgebers ignoring the complexity of humans. For example, some people may feel more alert in the morning or more alert at night irrespective of their sleep/wake cycle (early bird & night owl)

explain the weakness biological reductionism

behaviourists argue that bodily rhythms are also influenced by other people & social norms within an environment. For example, sleep occurs at dark because it is a social norm & would be dangerous to conduct daily activities at that time