circadian rhythm

• biological rhythms:

  endogenous pacemakers are internal influences on the body's rhythms. exogenous zeitgebers exert an external influence on the biological rhythms
• circadian rhythm lasts around 24 hours and is controlled by the suprachiasmatic nucleus
• sleep wake cycle:

  drowsy at night, alert during the day due to the infkuence of exogenous zeitgeber light. endogenous pacemaker suprachiasmic nucleus (scn) provides info about light. light can reset scn
• siffre:

  derprived natural light and had access to food and artificial light. spent 2 months in cave. thought it was september but it was august

  free running bio rhythm settled at 25 hours continuing sleep wake cycle
• folkard:

  12pps 3 weeks dark cave bedtime 11:45 wake time 7:45 sped the clock from 24 to 22 hours

  1 pp adjusted comfortably existence of free running bio clock not easily overrun by exogenous zeitgebers
• aschoff and weaver:

  convinced pps to spend 4 weeks in ww2 bunker

  all pps had sleep wake cycle 25 hours but one had 29 hours
• czeiser:

  sleep wake cycle 13-25 hours
• duffy:

  morning ppl bed early known as larks and evening ppl bed late wake late known as owls
• +used to improve medical treatments. circadian rhythms coordinate no. body processes such as HR led to the idea of therapeutics which is how treatment is administered in a way that corresponds with bio rhythms. aspirin taken at night to reduce blood platelet activity which reduces the risk of a heart attack in the morning (bonten 2015). shows circadian rhythms have a practical application by making treatments more effective
• -generalisation difficult to make. aschoff and weaver, and siffre based on small amount of pps, and seems that the sleep wake cycle can vary. research by czeiser 1999 found individual differences in sleep wake cycle vary 13-65hrs. duff larks and owls. siffre later study 1999 observed own sleep wake cycle and found out it had slowed down since he was young. means difficult to use data other than averages or may be meaningless
• -provides understanding of adverse consequences that occur when they're disrupted. night shift workers engaged in shift work experience reduced concentration at around 6am means more mistakes and accidents (bolvin 1996). research pointed out relationship between shift work and poor health. shows that research has real world economic implications in term of managing workers productivity