Circadian rhythms Flashcards
What is a circadian rhythm?
A type of biological rhythm which lasts for about 24 hours and regulates body processes.
What is an example of a circadian rhythm?
The sleep wake cycle as it makes us feel drowsy at night and alert during the day.
What was Siffre’s cave study?
Siffre spent several periods of time underground to study the effects on his biological rhythms. He was deprived of natural light and he resurfaced after two months in the cave, although he only believed that he had been there for a month. His biological rhythm settled into a 25 hour cycle and he continued to fall asleep and wake up on a regular schedule.
What did Aschoff and Wever do?
They convinced participants to spend 4 weeks in a bunker without natural light and they found they displayed a circadian rhythm of about 25 hours, suggesting our natural rhythm is longer but the exogenous zeitgeibers mean we have a cycle of 24 hours.
What did Folkard find?
He got a group of 12 people to live in a cave and to go to bed when the clock said 11.45, waking up when the clock said 7.45. They gradually sped up the clock, meaning the day was only 22 hours and only one participant adjusted, showing the circadian rhythm cannot be changed by the environment easily.
What are the strengths of research into the circadian rhythm?
There is practical application for working night shifts and showing how to improve productivity
There is practical application to drug treatments, showing when they are most effective.
What are the weaknesses of research into the circadian rhythm?
The studies use small samples, which means that they are hard to apply to entire populations.
There is poor control in studies, like in Siffre’s where he turned on an artificial light when he wasn’t asleep.
There are individual differences in when people prefer to go to bed and wake up, meaning it makes it difficult to generalise case studies to entire populations.
