exogenous zeitgebers

Question 1

what are exogenous zeitgebers?

Answer 1

external factors that affect of entrain our biological rhythms such as the influence of light on the s/w cycle.

Question 2

give an example of a key zeitgeber in humans

Answer 2

light

Question 3

why is light such an influential exogenous zeitgeber?

Answer 3

it can reset the main EP, the SCN which is involved in the s/w cycle. It can also influence key processes such as secretion of hormones and blood circulation. A study showed that light can be detected by skin receptors even when our eyes are closed which can affect our sleep wake cycle

Question 4

what is a limitation of exogenous zeitgebers? (environment)

Answer 4

they don’t have the same affect in all environments. Those who experience little light in winter and little darkness in summer tell a different story from the usual narrative. For example, those who live in the arctic circle have a similar sleep pattern all year round despite spending six months in almost total darkness. This suggests that the S/W cycle is primarily controlled by EPs and these can override EZs.