Endogenous pacemakers and exogenous zeitgebers -A-Level Psychology
Endogenous pacemakers and the sleep/wake cycle:
The SCN-is a tiny bundle of nerve cells in the hypothalamus of each hemisphere and is one of the primary endogenous pacemakers in mammalian species.It maintains circadian rhythms such as the sleep/wake cycle.The SCN receives information about light directly from the optic chiasm,even when the eyes are closed.This enables the biological clock to adjust to changing patterns of daylight during sleep.
Animal studies and the SCN-Patricia et al destroyed the SCN connections in the brains of 30 chipmunks then returned them to their natural habitat and observed them.Their sleep/wake cycle had disappeared and by the end of the study most of them had been killed by predators perhaps because they were awake and vulnerable to attack when they should have been asleep.
The pineal gland and melatonin-the SCN passes the info on day length and light that it receives to the pineal gland.During the night ,the pineal gland increases the production of melatonin which induces sleep.
Exogenous zeitgebers:
-are external factors in the environment that reset our biological clocks through entertainment .
Light-is a key zeitgeber for humans,it can rest the body’s main endogenous pacemaker(the SCN).It also has an indirect influence in key processes in the body that control such functions as hormone secretion and blood circulation.In a study by Campbell and Murphy,15 pps were awoken at various times when a light pad was shone on the back of their knees.There was a deviation in the sleep/wake cycle by 3 hours.This suggests that light is a powerful exogenous zeitgeber that does not necessarily rely on the eyes.They demonstrated that light may be detected by skin receptor sites on the body even when the same info is not received by the eyes.
Social cues-parents influence the sleep/wake cycle for infants as well as mealtimes and bedtimes.Research also suggests that adapting to local times for eating and sleeping is an effective way of entraining circadian rhythms and beating jet lag when travelling long distances.
Evaluation:
Ethics in animal studies-the chipmunk study lacked basic ethics as the chipmunks were exposed to considerable harm and subsequent risk.
Influence of exogenous zeitgebers may be overstated-studies of individuals who live in Arctic regions show normal sleep patterns despite prolonged exposure to light.This shows that there are occasions when exogenous zeitgebers may have little bearing in the internal rhythm.
Endogenous pacemakers are internal biological clocks that regulate our sleep-wake cycle and other bodily processes. They are controlled by our body’s natural rhythms and are responsible for maintaining our internal body clock.
Exogenous zeitgebers are external environmental cues that help regulate our internal body clock. They include factors such as light, temperature, and social cues.
Endogenous pacemakers and exogenous zeitgebers work together to regulate our sleep-wake cycle and other biological processes. Endogenous pacemakers are responsible for maintaining our internal body clock, while exogenous zeitgebers help synchronize our internal clock with the external environment.
Disruptions to endogenous pacemakers and exogenous zeitgebers can lead to a variety of health problems, including sleep disorders, mood disorders, and cognitive impairment.
Examples of exogenous zeitgebers include natural factors such as sunlight, temperature changes, and social cues such as meal times and daily routines.
Endogenous pacemakers and exogenous zeitgebers play a critical role in regulating our daily lives, including our sleep-wake cycle, alertness, and mood. Understanding how they work together can help us develop healthy habits and improve our overall well-being.
Melatonin is a hormone produced by the pineal gland that helps regulate our internal body clock. It is released in response to darkness and helps promote sleep by reducing alertness and lowering body temperature.
Maintaining healthy endogenous pacemakers and exogenous zeitgebers involves developing healthy habits, such as establishing regular sleep-wake cycles, getting enough sunlight during the day, avoiding blue light from electronic devices before bedtime, and maintaining a consistent daily routine.
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