Regulating sleep pattern, release of hormones, varying body temperature and blood pressure
Endogenous Pacemakers
Internal body clocks
Exogenous Zeitgebers
External cues to entrain internal body clocks
Sleep Wake Cycle
The suprachiasmatic nucles (SCN) is the EP as part of the hypothalamus located in the optic chiasm
When light is detected by the SCN, the pineal gland stops producing melatonin
Light is the primary EZ, alongside social cues
(+) A03: Siffre
Lived in a cave for 6 months, with no natural light source or other EZs
Siffres body clock adjusted to a 25 hour cycle, suggesting the EP is free running but needs entrainment
(+) A03: Vetter
27 Office workers circadian rhythm shifted due to increased exposure to blue light, making artifical light a strong EZ
(-) A03: Economic Implications - Boivin
Shift work has been found to lead to desynchronisation of circadian rhythms, leading to adverse and psychological effects; found night workers suffer a concentration lapse at 6am causing likelihood of accidents
(-) A03: Siffre Artificial Light
Siffre had an artificial light source whilst in the cave, this may of disrupted the cycle acting as an EZ, studies without light sources showed very little drift from 24 hours
