Biological rhythms: Circadian rhythms Flashcards
What are biological rhythms?
Patterns of changes in the body activity that conform to cyclical time periods. They are influenced by internal body clocks and external changes.
What are circadian rhythms?
Biological rhythms subject to a 24 hour cycle
What 2 things are biological rhythms influenced by?
Exogenous zietgebers (external) and endogenous pacemakers (internal)
What is an example of a circadian rhythm?
Sleep/wake cycle
What is the sleep/wake cycle governed by?
The suprachiasmatic nucleus (SCN) that provides information from they eye about light.
Describe Siffre’s cave study
- Spent 2 months in the caves of the Southern Alps
- Deprived of natural light and sound but had food and drink
- He resurfaced in September 1962 believing it to be mid-August
What happened to Siffre’s biological rhythm during his cave studies?
It settled down to one just beyonf 24 hours but he did fall asleep and wake up on a regular schedule
Describe Aschoff and Wever’s study (World war 2 bunker)
- Participants spent 4 weeks in a WW2 bunker with no natural light
- All but one participant showed a circadian rhythm between 24 and 25 hours
- Suggests that natural sleep/wake cycles may be slightly longer than 24 hours
What is a strength of research into circadian rhythms? (Understand the consequences of them being disrupted)
- E.g Night workers experience a period of reduced concentration around 6am meaning mistakes are more likely to happen
- Research has shown a link between shift work and poor health: shift workers are 3x more likely to develop heart disease than those who work typical work patterns
- Research as real world economical implications
What is a strength of research into circadian rhythms? (Improved medical treatments)
- Research has led to field of chronotherapeutics: how medical treatments can be given in a way that correspond’s to someones biological rhythm
- E.g Aspirin is most effective at reducing heart attacks when taken late at night as they are more likely to occur in the morning
- Can help improve the effectiveness of drug treatments
What is a limitation of the research into circadian rhythms? (Generalisations are hard to make)
- Studies are based on a small group of people however sleep/wake cycles differ from person to person
- Czeisler et al found that people’s sleep/wake cycles vary from 13 to 65 hours
- Duffy et al revealed people have preferences for going to bed early and waking up early or going to bed late and waking up late
- Research data is hard to discuss anythin more than averages
