AO3 - Circadian Rhythms

• Research to support circadian rhythms lasting around 24 hours was conducted by Siffre. He isolated himself in a cave for six months where his biological clock was able to be free running and unaffected by exogenous factors such as clocks and natural light. 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. Therefore, this supports that the sleep wake cycle is a circadian rhythm which is mainly controlled by an endogenous pacemaker, the SCN, to maintain a circadian rhythm.
• One limitation of the research by Siffre is low population validity. It was conducted as a case study with one participant so it may not be appropriate to generalise findings on the sleep wake cycle beyond Siffre due to individual differences in the sleep/wake cycle and circadian rhythms. For example, older people’s circadian rhythms may be slower and more easily influenced by exogenous zeitgebers, as even in one of Siffre’s later replications he found that his own circadian rhythm had slowed. Therefore, lowering the external validity of the research investigating circadian rhythms.
• A strength of the research into circadian rhythms is that it has practical applications. The principles of the theory that a circadian rhythm lasts 24 hours and maintained by endogenous pacemakers, gives researchers a better understanding of negative consequences resulting from disrupting their rhythm. For example, night workers have a period of reduced concentration around 6am meaning mistakes are more likely. This can be used by employers to manage worker productivity, which improves the economy. Therefore, research into circadian rhythms is an important part of applied psychology.