circadian rhythms
- Created by: Kerryn Ludlow
- Created on: 17-05-13 17:14
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- Circadian rhythms
- biological cycles lasting around 24 hours.
- the sleep/wake cycle is an example of this.
- this is facilitated by time checks and regular intervals such as meal times.
- exogenous pacemakers play an important role in the sleep/wake cycle, e.g. light
- controlled by an endogenous pacemaker
- this endogenous pacemaker is the superchaismatic nucleus
- research for the sleep/wake cycle
- Aschoff and Weber
- placed participants in a bunker with no natural light and the settled into a sleep/wake cycle between 25 - 27 hours.
- this suggests that the endogenous pacemaker controls the sleep/wake cycle in the absence of light cues.
- Siffre
- spent 6 months in a cave with no time cues. artificial lights came on when he was awake. He settled into a sleep/wake cycle of 25 to 30 hours.
- after 179 days he thought that only 151 had passed, supporting Aschoff and Weber's findings that endogenous pacemakers exert an influence of circadian rhythm, though the artificial light may have a confounding variable.
- Aschoff and Weber
- evaluation for the sleep/wake cycle
- there are individual differences in the sleep/wake cycle.
- Duffy et al found that early risers prefer 6am to 10pm and later risers prefer 10am to 1am
- Aschoff and Weber found in isiolation studies that some participants found it difficult to maintain normal cycles, while others strongly differ.
- isolation studies have few participants, so makes generalisation problematic.
- research suggests that endogenous pacemakers do exist and are regulated by exogenous zeitgabers
- isolating participants from the environment without controlling their behaviour may be insufficient to reveal the activity of the endogenous circadian pacemaker.
- participants were exposed to high levels of artificial light which may have screw the results by resetting the endogenous pacemaker.
- there are individual differences in the sleep/wake cycle.
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