biological cycles

• 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 body timing
• What is the process called that aligns endogenous pacemakers with external cues?

  Entrainment
• What is the duration of a circadian rhythm?

  Around 24 hours
• How do exogenous zeitgebers affect the sleep/wake cycle?

  They provide cues like light and social timing
• What is the SCN and its role in the sleep/wake cycle?

  It is the master clock regulating circadian rhythms
• Where is the SCN located?

  In the hypothalamus
• What hormone does the pineal gland produce?

  Melatonin
• How does light affect melatonin production?

  Light suppresses melatonin production
• What is a freerunning circadian rhythm?

  A rhythm maintained without external cues
• Who conducted studies on freerunning circadian rhythms?

  Seif
• What did Seif's studies in a cave demonstrate?

  The body clock can extend beyond 24 hours
• What criticism was made regarding Seif's studies?

  Participants controlled artificial light
• What did recent work by Caesar suggest about the endogenous pacemaker?

  It can maintain a precise 24-hour rhythm
• What did the 2011 study on blue light exposure find?

  It affected circadian rhythms in office workers
• What evidence supports the SCN as the endogenous pacemaker?

  Hamsters' rhythms changed with SCN transplants
• What implications does understanding circadian rhythms have for society?

  It can improve treatments for jetlag and productivity
• How does exposure to blue light at night affect sleep?

  It disrupts the biological clock
• What did research on a blind man reveal about circadian rhythms?

  He had a 24.9-hour circadian rhythm
• What is chronobiology?

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

  They can turn off their circadian rhythms
• What happens to arctic reindeer during the summer?

  They lose their circadian rhythm
• What is the significance of understanding circadian rhythms for health services?

  It helps in timing drug treatments