Exogenous Zeitgebers Flashcards
What are exogenous zeitgebers
external factors in the environment that reset our biological clocks through a process called entrainment
Describe light as an exogenous zeitgeber
key zeitgeber in humans
can reset the SCN and therefore plays a role in the maintenance of the sleep wake cycle
indirect influence on key processes in the body that control functions like hormone secretion and blood circulation
Describe research into light as an endogenous zeitgeber
Campbell and Murphy
light may be detected by skin receptors and not only by eyes
15 Pp woken up at different times and a light pad was shone on back of knees
Pp sleep/wake cycle deviates up to 3 hours
suggesting light is a powerful exogenous zeitgeber that does not rely on the eyes to exert its influence on the brain
What are social cues
by 16 weeks a babies circadian rhythms is entrained by the schedules imposed by the parents including adult determined mealtimes and bedtimes
What are the limitations of Exogenous Zeitgebers
do not have the safe effect in all environments
people who live in the arctic circle where 6 months consist of total darkness, have similar sleep patterns all year round
suggest the sleep wake cycle is primarily controlled by endogenous pacemakers that can override environmental changes in light
contrasting case study evidence
Miles et al studied a young man who was blind from birth and had an abnormal circadian rhythms of 24.9 hours
despite exposure to social cues such as regular mealtimes, his sleep/wake cycle could not be adjusted
suggests social cues alone are not effective in resetting the bio rhythm
