Circadian rhythms

• What are the biological cycles in the human body described in the study material?

  They occur predictably, some many times a day, some once every 24 hours, and some take weeks or years.
• What is an endogenous pacemaker?

  An endogenous pacemaker is an internal body clock that helps keep track of time.
• What does the term exogenous zeitgeber refer to?

  An exogenous zeitgeber is an external environmental cue that helps regulate the internal body clock.
• What is the Latin origin of the term circadian rhythm?

  Circadian rhythm comes from "circa" meaning around and "diem" meaning day.
• What is the most obvious example of a circadian rhythm?

  The sleep/wake cycle is the most obvious example of a circadian rhythm.
• How does light affect the sleep/wake cycle?

  Light detected by the SCN suppresses melatonin production, making you feel less sleepy.
• What happens during jet lag in relation to endogenous pacemakers and exogenous zeitgebers?

  Jet lag occurs when there is a conflict between exogenous zeitgebers and the internal body clock.
• What is the role of the suprachiasmatic nucleus (SCN)?

  The SCN is the endogenous pacemaker for the sleep/wake cycle.
• Where is the SCN located in the brain?

  The SCN is located in the hypothalamus within the limbic system.
• How does the SCN respond to light?

  The SCN is sensitive to the amount and type of light received from the eyes.
• What hormone does the pineal gland produce, and what is its effect?

  The pineal gland produces melatonin, which induces a sleep response.
• What is the significance of the study conducted by Siffre regarding circadian rhythms?

  Siffre's study showed that the endogenous biological rhythm can maintain itself without external cues.
• What did Siffre's findings suggest about the length of the circadian cycle in isolation?

  His findings suggested that the circadian cycle extended to around 25 hours in isolation.
• What criticism has been made regarding studies on circadian rhythms and artificial light?

  Critics argue that participants may alter their biological clock with the use of artificial lights.
• What did the 2011 study on blue light exposure reveal about circadian rhythms?

  The study showed that exposure to strong blue light affected circadian rhythms in office workers.
• What did Ralph's experiment with hamsters demonstrate about the SCN?

  Ralph's experiment demonstrated that the SCN is the endogenous pacemaker responsible for circadian rhythms.
• What are the implications of understanding circadian rhythms for psychology and health services?

  Understanding circadian rhythms can help develop treatments for jet lag and improve productivity for shift workers.
• How can exposure to blue light at night affect sleep patterns?

  Exposure to blue light at night can disrupt the biological clock and affect sleep quality.
• What did the research on a blind man reveal about circadian rhythms?

  The blind man had a circadian rhythm of 24.9 hours, indicating a lack of synchronization with society.
• What is chronobiology?

  Chronobiology is the study of biological rhythms, including circadian rhythms.
• How do some species adapt their circadian rhythms in extreme environments?

  Some species can turn off their circadian rhythms when conditions, like constant daylight, do not require them.