exogenous zeitgebers and endogenous pacemakers Flashcards
what are endogenous pacemakers?
Internal body clocks that regulate many of our biological rhythms
what is melatonin?
Produced by pineal gland at night, governs sleep/wake cycle. Production inhibited during periods of wakefulness
what is the main example of the EP?
the suprachiasmatic nucleus
what animal studies explore the SCN?
Decousey et al (2000)
Ralph et al (1990)
outline decousey et al?
destroyed scn of 30 chipmunks
let into wild and observed for 80 days
no longer had sleep-wake cycle
most killed by predators
role of scn on sleep wak cycle
outline ralph et al?
bred mutant hamsters with 20hr sleep wake cycles, took SCN cells and given to normal hamster brains
normal hamsters adopted new sleep wake cycle from mutants
ao3 ethics? endogenous pacemakers
limitation
harm to animals, unethical
cp- cant do to humans, needs to happen
ao3 generaliseability? endogenous pacemakers
limitation
human brains more complex than animals do cant generalise results
what are exogenous zeitgebers?
External cues in the environment that entrain our biological rhythms
what are the 2 main EZ’s?
light and social cues
what is light?
A zeitgeber in humans that can reset the main endogenous pacemaker (SCN) and plays a role in the sleep/wake cycle.
what are social cues?
Schedules created by others, e.g. mealtimes and bedtimes.
what study explores the effect of light on sleep-wake cycle?
Campbell and Murphy 1998
15 ppts woken at various times with light pod shining on back of knees
deviates cycle, light most powerful
ao3 environmental observations? exogenous zeitgaber
limitation
not same effect in places with low light, still have 24hr sleep cycles so more internal influences
ao3 case study evidence +cp? exogenous zeitgaber
limitation
miles et al (1977)
blind man from birth, unusual sw cycle 24.9hrs despite social cues, non effective.
cp- case study cant generalise to others
