Endogenous pacemakers and exogenous zeitgebers on sleep/wake cycle Flashcards
What are biological rhythms influenced by?
Internal body clocks (endogenous pacemaker).
External cues within the environment (exogenous zeitgeber).
What are endogenous pacemakers?
Internal body clocks that regulate many of our biological rhythms, such as the suprachiasmatic nucleus (SCN) on the sleep/wake cycle
What’s the Suprachiasmatic Nucleus?
Tiny bundle of nerve cells found in the hypothalamus in each hemisphere.
Primary endogenous pacemaker which helps maintain our circadian rhythms.
When it is light the SCN which lies in the visual area of the cerebral cortex detects this. This processing occurs when our eyes are shut, which also helps us to adjust to changing patterns of daylight whilst we are asleep.
How does the pineal gland link to melatonin?
The SCN passes the information on day length & light to the pineal gland. This lies just behind the hypothalamus.
During the night, the pineal gland increases the production of melatonin (which helps bring on sleep). When we wake the pineal gland will reduce the production of melatonin, which helps us stay awake.
What are exogenous zeitgebers?
External cues that may affect our biological rhythms such as the influence of light on our sleep/wake cycle.
How is light an example of exogenous zeitgebers?
Light is a key zeitgeber as it activates the SCN which is involved in the sleep/wake cycle.
In one study, they demonstrated how influential light was on this cycle by shining a torch on the back of people’s knees whilst they slept. The researchers managed to disrupt some cycles by up to 3 hours. This shows that light is an influential factor which does not just have to be detected with the eyes.
How are social cues an example of exogenous zeitgebers?
In babies, their sleep/wake cycles are random- they begin to form at the age of 6 weeks and become regular at 16 weeks.
Parents use social cues in the form of schedules such as feeding and nap times to regulate their baby’s cycle.
What are the strengths of endogenous and exogenous zeitgebers?
What are the limitations of endogenous and exogenous zeitgebers?
