controls for cycles

• exogenous zeitgebers - external influences
• endogenous pacemakers - internal influences
• pineal gland - releases melatonin to help us feel sleepy
• scn - suprachiasmatic nucelus
• pineal gland controlled by scn
• scn located in the hypothalamus
• scn sends signals to pineal gland - when to increase or decrease melatonin
• scn is an endogenous pacemaker
• ralph - hamster study
• hamster study - removed scn to test reactions - with no scn did not follow a pattern swapped scn in normal hamster and abnormal hamster with 21 hour sleep wake cycle
• hamster results - changed sleep wake cycle to match new scn
• issues with ralphs study - unethical - animal study