Circadian Rhythms

    Cards (20)

    • Circadian rhythms are biological rhythms that last for around 24 hours e.g. sleep-wake cycle, core body temperature
    • Siffre's cavy study investigated the sleep-wake cycle as he spent 6 months in a cave in the Alps deprived of exposure to natural light and sound
    • Siffre resurfaced in mid-september believing it to be mid-august
    • Siffre's free-running circadian rhythms settled to about 25 hours
    • The sleep-wake cycle is governed by the SCN and light
    • The sleep-wake cycle has two dips between 2-4 AM and 1-3 PM
    • In the absence of exogenous zeitgebers the free-running circadian rhythm would last 25 hours
    • Core Body Temperature varies by about 2 degrees every day
    • Core body temperature is lowest at 4AM (36) and highest at 6PM (38)
    • Warmer body temperature increases cognitive performance
    • Folkard et.al investigated the sleep-wake cycle using 12 participants who spent 3 weeks in a cave whilst researchers gradually sped up the clock
    • Folkard et.al found that the majority of participants were unable to comfortably adjust
    • Shift work demonstrates circadian rhythms as night workers have been shown to experience a period of reduced concentration at around 6AM which increases the likelihood of mistakes
    • There has to been shown to be a relationship between shift work and poor health
    • Knuttson found that shift-workers are 3 times more likely to develop heart disease
    • Research into medical treatment supports circadian rhythms e.g. Chronotherapeutics
    • Chronotherapeutics is when medical treatments can be administered in a way that corresponds to someone's biological rhythms
    • An example of chronotherapeutics is that aspirin is more effective for heart attacks when taken late at night
    • There are individual differences in circadian rhythms as cycles can vary from 13-65 hours
    • Jeane Duffy et.al supports individual differences as she found that some paeople are 'larks' or 'owls' due to natural preferences
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