Circadian rhythms: occur every 24 hours.
Endogenous pacemakers = internal body clock which regulates body rhythms
Exogenous zeitgebers = external body clock from environment which resets our
biological clock.
Sleep/wake cycle: in the morning, when natural light is more apparent, the SCN
instructs the pineal gland to decrease production of melatonin. During night
time when natural light fades, SCN triggers production of melatonin so they’d
become more sleepy.
Its affected by EG and EP. EP – SCN regulates sleep producing hormones. EG –
natural light acts as a trigger for waking up.
Siffre cave study – the effect on sleep/wake cycle with only endogenous
pacemakers. 2 months and 7 months in a cave without any natural light. He
found that his sleep/wake cycle only changed to 25 hours, therefore his
internal body clock (EP) still set itself without the need for exogenous
zeitgebers. Suggests we are entrained by EG associated w a 24-hour day e.g.
typical meal times, no of daylight hours.
Folkard – shouldn’t overestimate influence of EZ on our internal biological
clock. Isolated 12 p’s in a dark cave, manipulated clocks so only 22 hours
passed a day. Found none of the p’s adjusted well suggesting existence of a
strong circadian rhythm that can’t be easily overridden by external
environment changes.
Ao3 to circadian rhythms:
Supporting studies in this area are often case studies or use small sample sizes
so many not be generalisable. However some are longitudinal studies e.g. siffre
7 months, therefore more certain that changes in his rhythms weren’t just
temporary factors.
Knowledge about circadian rhythms has been used to improve medical
treatments. Circadian rhythms co-ordinate a no of bodily processes like heart
rate and hormone levels, which has led to chronotherapeutic which is where
drugs are administered in a way that corresponds with the biological rhythm of
the person. Therefore its increased effectiveness of drug treatments.
Endogenous pacemakers = internal body clock which regulates body rhythms
Exogenous zeitgebers = external body clock from environment which resets our
biological clock.
Sleep/wake cycle: in the morning, when natural light is more apparent, the SCN
instructs the pineal gland to decrease production of melatonin. During night
time when natural light fades, SCN triggers production of melatonin so they’d
become more sleepy.
Its affected by EG and EP. EP – SCN regulates sleep producing hormones. EG –
natural light acts as a trigger for waking up.
Siffre cave study – the effect on sleep/wake cycle with only endogenous
pacemakers. 2 months and 7 months in a cave without any natural light. He
found that his sleep/wake cycle only changed to 25 hours, therefore his
internal body clock (EP) still set itself without the need for exogenous
zeitgebers. Suggests we are entrained by EG associated w a 24-hour day e.g.
typical meal times, no of daylight hours.
Folkard – shouldn’t overestimate influence of EZ on our internal biological
clock. Isolated 12 p’s in a dark cave, manipulated clocks so only 22 hours
passed a day. Found none of the p’s adjusted well suggesting existence of a
strong circadian rhythm that can’t be easily overridden by external
environment changes.
Ao3 to circadian rhythms:
Supporting studies in this area are often case studies or use small sample sizes
so many not be generalisable. However some are longitudinal studies e.g. siffre
7 months, therefore more certain that changes in his rhythms weren’t just
temporary factors.
Knowledge about circadian rhythms has been used to improve medical
treatments. Circadian rhythms co-ordinate a no of bodily processes like heart
rate and hormone levels, which has led to chronotherapeutic which is where
drugs are administered in a way that corresponds with the biological rhythm of
the person. Therefore its increased effectiveness of drug treatments.
