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 process of entrainment?


  Entrainment is the process by which external cues synchronize the internal body clock.
• What is the definition of circadian rhythm?


  A circadian rhythm is a biological rhythm that lasts around 24 hours.
• What is the most obvious example of a circadian rhythm?


  The sleep/wake cycle is the most obvious example of a circadian rhythm.
• How do exogenous zeitgebers affect the sleep/wake cycle?


  Exogenous zeitgebers, like light and social cues, can influence when we sleep and wake.
• What is jet lag an example of?


  Jet lag is an example of the 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?


  The SCN is located in the hypothalamus within the limbic system.
• What hormone does the pineal gland produce?


  The pineal gland produces melatonin.
• How does light affect melatonin production?


  Light suppresses the production of melatonin, making you feel less sleepy.
• What evidence supports the existence of a free-running circadian rhythm?


  Research by Siff showed that individuals in isolation maintained a sleep/wake pattern extending beyond 24 hours.
• What did Siff's study involve?


  Siff spent 179 days in a cave without access to natural light or clocks.
• What criticism has been made regarding studies on free-running circadian rhythms?


  Critics argue that participants had control over artificial lights, potentially altering their biological clock.
• What did more recent work by Caesar suggest about the endogenous pacemaker?


  Caesar's work suggests that the endogenous pacemaker is precise and capable of maintaining a 24-hour rhythm.
• What did the 2011 study by better demonstrate?


  It demonstrated that exposure to strong blue light can influence circadian rhythms.
• What did Ralph's research on hamsters reveal?


  Ralph's research showed that the SCN is the endogenous pacemaker responsible for the circadian rhythm in the sleep/wake cycle.
• What happens when the SCN of mutant hamsters is replaced with that of normal hamsters?


  The mutant hamsters adopt a normal 24-hour circadian rhythm after receiving the SCN from normal hamsters.
• What are the implications of understanding circadian rhythms for psychology?


  Understanding circadian rhythms can help develop treatments for jet lag and improve productivity for shift workers.
• What is chronobiology?


  Chronobiology is the study of biological rhythms.
• How can circadian rhythms be affected by environmental conditions?


  Circadian rhythms can be turned off in certain species when environmental conditions, like constant daylight, are present.
• What is a unique adaptation of arctic reindeer regarding circadian rhythms?


  Arctic reindeer can lose their circadian rhythm during the Arctic summer when the sun never sets.
• What did the research on a blind man by Miles reveal about circadian rhythms?


  It revealed that even with social cues, the blind man had a circadian rhythm of 24.9 hours, out of sync with society.
• What is the significance of light in relation to circadian rhythms?


  Light is a dominant exogenous zeitgeber that influences circadian rhythms.
• How do social cues affect circadian rhythms?


  Social cues, like meal times and exercise, can also act as exogenous zeitgebers to influence circadian rhythms.
• What is the evolutionary explanation for the day/night cycle in humans and other animals?


  The evolutionary explanation suggests that humans are specialized for daytime activity, while nocturnal animals have adapted to be active at night.
• What is a fact about cyanobacteria in relation to circadian rhythms?


  Cyanobacteria also exhibit circadian rhythms.
• How do migrating birds manage their circadian rhythms?


  Migrating birds can turn off their circadian rhythms for weeks to facilitate their journey.
• What is the significance of understanding circadian rhythms for health services?


  Understanding circadian rhythms can help in timing drug treatments and improving health services like the NHS.