Biological Rhythms

  • Created by: Katherine
  • Created on: 26-03-15 10:10
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  • Biological Rhythms
    • Infradian Rhythms-last more than 24 hours. E.g. menstrual cycle & SAD
      • Russel et al- applied underarm sweat of donor women to upper lips of female P's. The menstrual cycles became synchronised.
        • A02- Evolutionary theory. Women want synchronised pregnancies which allows sharing child care- survival value.
      • Rosenzweig et al (1999)- SAD. Winter darkness brings on low moods. Associated with darkness stimulating the production of melatonin. Stressing importance of light as an exogenous zeitgeber.
        • A02- A  practical application of research into SAD is that it has lead to development of successful light therapies to treat the condition.
      • EVALUATION- Women's cycles are not universal, which may invalidate findings.
    • Ultradian Rhythms-lasting less than 24 hours. E.g. stages of sleep. (Light SWS to deep SWS, the back to light SWS and then to REM sleep is approx 90 mins cycle)
      • NB. SWS= slow wave sleep.
      • Rechtschaffen and Kales- measured electrical activity of the brain with an EEG, finding different patterns of activity at different times of sleep.
      • EVALUATION-If you are being tested for your sleep patterns within a lab- extrenuous variables such as stress may affect results.
    • Circadian Rhythms- Repeated over a 24 hour period. E.g. the Sleep-wake cycle & body temperature.
      • Siffre (1972)- sleep-wake cycles remain despite external cues. -implies endogenous pacemakers exert a strong influence on circadian rhythms.
      • EVALUATION-Individual differences exist in sleep-wake cycles. Isolation studies have few participants making generalisation problematic.


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