Biopsychology: Exogenous zeitgebers Flashcards
What are exogenous zeitgebers?
External factors in the environment that reset our biological clocks
What is the process called when our biological clocks are reset?
Entrainment
What is an example of a key zeitgeber in humans?
And what does it do?
And what does it play a role in?
Light
- Can reset the body’s main endogenous pacemaker, the SCN
- The maintenance of the sleep/wake cycle
What does light have an indirect influence on?
Key processes in the body that control such functions= hormones secretion & blood circulation
What did Campbell & Murphy demonstrate?
That light can be detected by skin receptor sites on the body even when the same information is not received by the eyes.
How did Campbell & Murphy demonstrate this?
Procedure?
Results?
What does this suggest?
Procedure:
- 15 participants were woken at various times
- A light pad was shone at the back of their knees
Results:
- Researchers managed to produce a deviation in the p’s usual sleep/wake cycle of up to 3 hrs in some cases
Suggests:
- light is a powerful exogenous zeitgeber
- doesn’t necessarily rely on the eyes to exert its influence on the brain
What is the sleep/wake cycle like for newborn babies?
Pretty random
What age in babies does the circadian rhythm begin? and then what age are they entrained by the schedules imposed by parents?
- 6 weeks
- 16 weeks
How happens to the babies rhythm at 16 weeks?
Babies rhythms become entrained by the schedules imposed by parents
What happens in babies at 6 weeks?
Their circadian rhythm begins
What’s an example of schedules imposed by parents when we are babies to help entrain our circadian rhythms?
Adult-determined mealtimes & bedtimes
What does research on jet lag suggest we should do?
Adapt to local times for eating and sleeping = an effective way of entraining circadian rhythms & beating jet lag when travelling long distances
EVALUATION: 1/2 limitations of exogenous zeitgebers
POINT: They do not have the same effect in all environments
EVIDENCE:
- people who live in the arctic circle (e.g. Inuits of greenland) have similar sleep/wake patterns all year round
- despite spending around 6 months in almost total darkness
EXPLAIN:
- the experience of people who live in places where there is very little darkness in summer and very little light in winter tell a different story
LINK:
- suggests that the sleep/wake cycle is primarily controlled by endogenous pacemakers
- that can override environmental changes in light
EVALUATION: 2/2 limitations of exogenous zeitgebers
POINT: There is case study evidence that challenges the role of exogenous zeitgebers
EVIDENCE: Miles et al
- recount the study of a young man, blind from birth, who had an abnormal circadian rhythm of 24.9 hrs
EXPLAIN:
- despite exposure to social cues (e.g. regular mealtimes)
- his sleep/wake cycle could not be adjusted
LINK: Suggests that social cues alone are not effective in resetting the biological rhythm
