Pacemakers and Zeitgebers

1786 Words8 Pages
Describe and evaluate research into pacemakers and zeitgebers Endogenous pacemakers act as the ‘internal biological clock’ within the human body- e.g they act independently of external factors. Zeitgebers are external factors that influence when we feel tired, such as lack of light. There has been much research into both over the last few decades. One of the main studies into the effects of pacemakers on the circadian rhythm of human is a study done by scientist and explorer, Michael Siffre. He spent six months in a Texan cave in 1975 and during this time he didn’t receive any cues as to whether it was day or night. During his stay there he was well fed and regularly exercised. He was also allowed to use to phone to contact people. The time he slept each ‘day was recorded and he took daily measurement on himself to check he was healthy. It was found that his circadian rhythm changed to about twenty-five hours, but at times dramatically increased to forty-eight hours. Therefore, this study suggests that pacemakers regulate our circadian rhythm to be at about twenty-five hours. In a similar study that Siffre conducted in 1999 (he was sixty years old) he found that his internal clock ticked more slowly than when he was a young man, suggesting pacemakers slow with age. A weakness of this study is that it is a case study- Siffre was the only participant. This means that any findings from this research may be applicable to Siffre, but not to the general population. Therefore this study lacks population validity and hence the result cannot be generalised. Another possible weakness is that, despite Siffre’s control of the environment (secluding himself in a cave), there may have been zeitgebers that were affecting his circadian rhythm. For example, he was allowed to use the phone. Whilst doing so there is a possibility he could gauge the sleepiness of the voice of
Open Document