Exogenous zeitgebers

• What does the German word Zeitgeber mean?

  Time giver
• What are exogenous zeitgebers?

  External factors in the environment that reset our biological clocks
• Through what process do exogenous zeitgebers reset our biological clocks?

  Entrainment
• What is a key zeitgeber in humans?

  Light
• What can light do to the SCN?

  Reset it
• What does light have a direct influence on?

  The sleep/wake cycle
• What does light have an indirect influence on?

  Key processes such as hormones
• Whose study showed that light may be detected by skin receptor sites even when the same information is not recieved by the eyes?

  Campbell and Murphy
• How many participants did Campbell and Murphy have?

  15
• What was the procedure in Campbell and Murphy's study?

  Woken up at various times and a light pad shone on back of knees
• What did Campbell and Murphy find?

  They could produce deviation of sleep/wake cycle up to three hours
• What does Campbell and Murphy's study suggest?

  Light is powerful zeitgeber that doesn't necessarily rely on eyes
• What does research on jet lag suggest?

  Adapting to local times for eating and sleeping is effective way of entraining circadian rhythms