Endogenous pacemakers and exogenous zeitegebers

• How does light affect the sleep-wake cycle?

  Light (the exogenous zeiteber) detected by the SCN (Endogenous pacemaker) which activated pineal gland to stop melatonin secretion, promoting wakefulness
• What happens when light is no longer detected at night?

  Lack of light (Exogenous zeiteber) activates The SCN signals the pineal gland (Endogenous pacemaker) to start secreting melatonin which creates tiredness
• How has studying circadian rhythms benefited healthcare?

  It has led to new medications and treatments for health conditions
• Why is the variability of circadian rhythms important in research?

  It indicates that individual differences must be considered in studies
• How does recognizing individual differences in circadian rhythms improve healthcare?

  It leads to more personalized and effective healthcare solutions
• What are Exogenous Zeitebers?

  External factors that effect our circadian rhythms eg. Light
• What are Endogenous Pacemakers?


  Internal factors that effect our circadian rhythm eg. SCN and Pineal Gland in the secretion of melatonin
• Strength of Circadian rhythms (Endogen pacemakers and exogen zeitebers)


  Research by Siffre- Lived in Cave with no natural light (to act as exogenous zeiteber)

  Found endogenous pacemaker extended rhythm to 25 hours
• Whats the issue with Siffre's research?


  Case study = cant generlise findings to wider population