exogenous zeitgebers Flashcards
what are exogenous zeitgebers?
external factors that affect of entrain our biological rhythms such as the influence of light on the s/w cycle.
give an example of a key zeitgeber in humans
light
why is light such an influential exogenous zeitgeber?
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
what is a limitation of exogenous zeitgebers? (environment)
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 environmental changes in light.
Explain the study involved with the effect of light on the sleep wake cycle
Campbell and Murphy demonstrated that light may be detected by skin receptor sites on the body even when the same info is not received by the eyes. 15 pps were woken at various times and a light pad was shone on the back of their knees. The researchers managed to produce a deviation in the pps usual sleep wake cycle of up to 3 hours in some cases. This suggests that light is a powerful EZ that doesn’t need to rely on the eyes to exert its influence on the brain
Explain how social cues are an exogenous zeitgeber
Many babies are not usually on the same sleep wake cycle as their parents, most newborn babies initial sleep wake cycle is completely random. However around the age of six weeks, the circadian rhythms begin and babies begin to be trained by schedules imposed by parents.
Research on jet lag suggests that adapting to local times for eating and sleeping, rather than responding to one’s own feelings of hunger and fatigue is an effective way of entraining circadian rhythms and beating jet lag.
