Outline and evaluate one or more biological rhythms
One biological rhythm is the Circadian rhythm. This takes that there is a biological predisposition with duration of 24 that regulates our core levels. They include temperature, heart rates etc. The rhythm explains why we sleep once every 24 hours. Our underlying circadian rhythm regulates our sleep/wake patterns. As a result, the average adult human sleeps for 7/8 hours per 24 hour cycle.
There is evidence to support the propositions of the Circadian rhythm. For example, the case study of Siffre supports this claim. He spent 172 days isolated from the outside world. He lived on his own schedule; as a result there were no external cues to regulate his sleep wake pattern. He slept when he wanted. At the end of the experiment, his body was on a 26 hour cycle. This supports the idea of an internal biological rhythm that regulates our sleep wake cycle. There must be an endogenous pacemaker that regulates our sleep. However the fact that he was on a 26 hour cycle instead of a 24 hour cycle suggests that our biological rhythm may be slightly longer and our external cues regulate us to a 24 hour in real life. The problem with the results from Siffre is that it is a case study, therefore we can’t generalise the results and come to the conclusion that we all possess 26 hour cycles because of the large individual differences in biological rhythms. Irrespective of this, the study still supports the idea of an internal rhythm that regulates our sleep/wake cycle. This idea is also supported by Luce and Segal, who studied those who lived near the Arctic Circle when the sun doesn't set. They found that the participants still lived on a 7-8 hour sleep/wake cycle. Therefore, they concluded that irrespective of light, there is an innate internal rhythm inbuilt in us.
Although there is supporting evidence for the existence of an internal circadian rhythm, there is also large evidence to support the…