Circadian rhythms Flashcards
Give an example of endogenous pacemakers being altered by the environment
Light can affect our sleep-wake cycle
Even though it will continue to function without natural cues from light, research suggests light is required to reset the sleep-wake cycle every 24 hours
What is the most important endogenous pacemaker and where is it?
Suprachiasmatic nucleus (SCN)
Lies in the hypothalamus
What is the role of the SCN?
Controls other biological rhythms as it links to other areas of the brain responsible for sleep and arousal
Receives information about light levels from optic nerve so that it is in synchronisation with outside world
Sends signals to pineal gland, leading to increase in production of melatonin at night
What exogenous Zeitgebers can affect biological rhythms?
Mainly light, also social cues, such as meal times or social activities
What is another example of a circadian rhythm?
Temperature is at its lowest in the early morning and highest in the early evening
Sleep typically occurs when the body’s core temperature starts to drop
Research support?
Siffre (1975) found the absence of external cues significantly altered his circadian rhythms
When he returned from an underground stay withy no clocks or light, he believed the date to be a month earlier than it was
This suggests his 24 hour sleep cycle was increased by a lack of external cues
Individual differences?
Duffy et al (2001) found that ‘morning people prefer to get up and go to bed early, whereas ‘evening people’ prefer to rise and go to bed late, demonstrating that there may be innate individual differences in circadian rhythms
Temperature?
Suggested that temperature more important than light
Buhr et al (2010) found that fluctuations in temperature set timing of cells in body and caused tissues and organs to become active or inactive
Circadian rhythms are affected by multiple factors, a holistic approach may be more appropriate
