Biological Rhythms od sleep

HideShow resource information
View mindmap
  • Sleep- Circadian Rhythms
    • Circadian Rhythms are rhythms that last about 24 hours
  • examples of these are: the sleep wake cycle and the body temperature cycle
    • Circadian Rhythms are rhythms that last about 24 hours
  • Sleep wake cycle
    • under normal circumstances the internal clock doesn't work alone
      • It needs both endogenous and exogenous factors  to keep it in sync
  • controlled by endogenous pacemakers  (internal mechanisms) and  exogenous zeitgebers ( external forces)
    • the internal circadian rhythm,( is free running) without any external cues runs on a cycle of about 24- 25 hours
  • core body temp is one of the best indicators of a circadian rhythm
    • Core body temperature
    • Its lowest is around 4:30am (36 degrees)           its highest is around 6:00 pm (38 degrees)
      • There is also a trough after lunch, the dip occurs even when people haven't eaten
    • Temp dip is a bi- daily rhythm
  • Hormones
    • Hormone production follows a circadian rhythm
    • Cortisol: is at its lowest around midnight and peaks around 6am
      • Cortisol is our ' wake up' hormone
        • makes us alert and awake- it is also released when we are stressed
        • Cortisol
          • Cortisol: is at its lowest around midnight and peaks around 6am
            • Cortisol is our ' wake up' hormone
              • makes us alert and awake- it is also released when we are stressed
              • Cortisol
    • they didn't t think that it would affect the circadian rhythm as natural day light would
      • such as clocks and radios
        • There where not isolated from artificial light
      • Czeisler (1999)
        • Altered participant circadian rhythm down to 22 hours and 28 hours by using dim lighting
    • individual difference
      • Evaluation
        • Sleep wake cycle- Research method
          • In all studies participants where isolated from variables that would affect their circadian rhythm
            • such as clocks and radios
              • There where not isolated from artificial light
        • Sleep- Circadian Rhythms
          • Core body temperature
            • Folkard (1977)
              • Read stories to 12- 23 year olds at either 9 am or 3pm
                • after 1 week the 3pm group ( higher body temp) showed better recall - up to 8% more meaningful material
                  • long term recall is best when the body temp is at its hightest
            • can be used to explain cognitive functions
            • Gupta (1991)
              • found performance on IQ tests were best at 7pm as opposed to 9am or 2 pm
          • Cause or correlation?
            • evidence suggests that temp changes does affect cognitive performances
            • Glesbrech ( 1993)
              • lowered participants body temp using cold water - found cognitive performances worsened
            • Hord and Thomson ( 1983)
              • did field experiment as opposed to lab and did find a correlation between core temp and cognitive functions
        • two types of individual differences
          • cycle length
            • Research has found that circadian cycles in different people can vary from 16 to 65 hours
          • cycle oneset
            • individuals are innately different in terms of when their circadian rhythm peaks
            • Duffy (2000)
              • found that morning people prefer to rise early and go to bed late
                • 6:00am and 10:00pm
              • evening people prefer to wake and go to bed late
                • 10:00am and 1:00am

      Comments

      No comments have yet been made

      Similar Psychology resources:

      See all Psychology resources »See all Sleep resources »