Circadian Rhythms

• What is the 24-hour biological rhythm known as?

  Circadian rhythm
• What resets the circadian rhythm?

  Levels of light
• What does the term 'circadian' mean?

  'About a day'
• What is an example of a circadian rhythm?

  Sleep-wake cycle
• How does light affect the sleep-wake cycle?

  It acts as an external cue
• What role do the suprachiasmatic nuclei (SCN) play?

  They coordinate the circadian system
• What is homeostasis in relation to sleep?

  It signals the need for sleep
• When does the homeostatic drive for sleep reach its maximum?

  Late evening
• What is the lowest human body temperature recorded?

  36 °C at 4:30 am
• When does sleep typically occur in relation to body temperature?

  When core temperature starts to drop
• What happens to body temperature towards the end of a sleep cycle?

  It starts to rise
• What research supports the concept of circadian rhythms?

  • Siffre (1975) study on absence of cues
  • Found altered circadian rhythm without light
  • Believed date was a month earlier
• What did Siffre's study suggest about circadian rhythms?

  They can be altered by external cues
• What did Duffy et al. (2001) find about individual differences?

  Morning and evening people have different cycles
• What are 'morning people' characterized by?

  Waking early and sleeping early
• What are 'evening people' characterized by?

  Waking late and sleeping late
• What did Buhr et al. (2010) suggest about temperature?

  It may be more important than light
• How do fluctuations in temperature affect circadian rhythms?

  They set the timing of body cells
• What does Buhr claim about light levels and body temperature?

  Light levels transform into neural messages
• What does the fluctuation of body temperature indicate?

  It sends signals to our body clocks
• What are the key factors affecting circadian rhythms?

  • Light levels
  • Body temperature
  • Individual differences
  • Homeostasis
• What is a holistic approach in circadian rhythm research?

  • Considers multiple factors
  • Includes light, temperature, and individual differences
  • Aims for comprehensive understanding