The Sleep Wake Cycle: Circadian Rhythm

• What are the biological cycles in the body described as?

  Predictable cycles occurring at various intervals
• What is the role of endogenous pacemakers?

  They act as an internal body clock
• What does the term 'exogenous zeitgeber' refer to?

  External cues that influence biological rhythms
• What is 'entrainment' in relation to biological rhythms?

  It is the process of synchronizing internal clocks
• What is a circadian rhythm?

  A biological rhythm lasting around 24 hours
• How do exogenous zeitgebers affect the sleep/wake cycle?

  They provide cues that influence sleep timing
• What is the role of the suprachiasmatic nucleus (SCN)?

  It acts as the master clock for circadian rhythms
• Where is the SCN located?

  In the hypothalamus within the limbic system
• How does light affect melatonin production?

  Light suppresses melatonin production
• What is the effect of social cues on circadian rhythms?

  They can help reset the biological clock
• What does 'free-running' mean in circadian rhythms?

  Maintaining a rhythm without external cues
• What did Siffre's studies demonstrate about circadian rhythms?

  They can extend beyond the normal 24-hour cycle
• What criticism exists regarding studies on free-running rhythms?

  Participants may control artificial light exposure
• What did Ralph's experiment with hamsters show?

  SCN is the endogenous pacemaker for rhythms
• What are the implications of understanding circadian rhythms?

  They can improve treatments for sleep disorders
• How does exposure to blue light affect circadian rhythms?

  It can disrupt natural sleep patterns
• What is chronobiology?

  The study of biological rhythms
• How do some species adapt their circadian rhythms in extreme environments?

  They can turn off their rhythms when needed
• What are the key components of circadian rhythms?

  • Endogenous pacemakers (internal clocks)
  • Exogenous zeitgebers (external cues)
  • Suprachiasmatic nucleus (master clock)
  • Hormonal regulation (e.g., melatonin)
• What are the effects of disrupted circadian rhythms?

  • Increased anxiety
  • Decreased alertness
  • Decreased vigilance
  • Impacts on overall health and performance
• How can knowledge of circadian rhythms benefit society?

  • Improve treatments for jetlag
  • Enhance athlete performance
  • Aid shift workers' productivity
  • Optimize timing for drug treatments
• What are the differences between nocturnal and diurnal animals regarding circadian rhythms?

  • Diurnal animals are active during the day
  • Nocturnal animals are active at night
  • Circadian rhythms are adapted to their activity patterns