Endogenous Pacemakers+Exogenous Zeitgebers.
-Gave lesioned brains to hamsters, resulting in a shorter sleep cycle at 20 hours. They adopted the same patterns as the lesioned hamsters, supporting the SCN and showing it as primarily endogenous.
-UItilitarian perspective, and ethics are affected.
-Well controlled, so easy to replicate, but can it be generalised, due to them being animals?
-Removed the SCN from 30 chipmonks. Also used surgical controls and intact controls.She then leased them back into their naturl habitat, and observed. After 80 days, most of the lesioned chipmunks had been killed, due to them remianing awake during times when they should be asleep resulting in their death. Therefore, SCN also has an evolutionary advantage.
-More natural, so more ecological valid, but hard to replicate.
-Stayed in a cave for 6 days. His sleep wake cycle increased, meaning when he emerged, he had lost 28 days. This supports exogenous zeitgebers, as they control our cycle. A free running body clock
Campbell and Murphy
-Shone a light onto th back of participnats legs, altering their circadian rhythm, this may have been due to the SCN picking up alterations of blood chemistry.
Aschoff and Weaver
-Students stayed in a bunker for a month, but had gained a 25 hour cycle, losing an hour a day.
Disruption biological rhythms