Biological Rhythms od sleep
- Created by: Beckyklake
- Created on: 20-02-15 11:32
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- Sleep- Circadian Rhythms
- Circadian Rhythms are rhythms that last about 24 hours
- examples of these are: the sleep wake cycle and the body temperature cycle
- Circadian Rhythms are rhythms that last about 24 hours
- Sleep wake cycle
- under normal circumstances the internal clock doesn't work alone
- It needs both endogenous and exogenous factors to keep it in sync
- under normal circumstances the internal clock doesn't work alone
- controlled by endogenous pacemakers (internal mechanisms) and exogenous zeitgebers ( external forces)
- the internal circadian rhythm,( is free running) without any external cues runs on a cycle of about 24- 25 hours
- core body temp is one of the best indicators of a circadian rhythm
- Core body temperature
- Its lowest is around 4:30am (36 degrees) its highest is around 6:00 pm (38 degrees)
- There is also a trough after lunch, the dip occurs even when people haven't eaten
- Temp dip is a bi- daily rhythm
- Hormones
- Hormone production follows a circadian rhythm
- Cortisol: is at its lowest around midnight and peaks around 6am
- Cortisol is our ' wake up' hormone
- makes us alert and awake- it is also released when we are stressed
- Cortisol
- Cortisol: is at its lowest around midnight and peaks around 6am
- Cortisol is our ' wake up' hormone
- makes us alert and awake- it is also released when we are stressed
- Cortisol
- Cortisol is our ' wake up' hormone
- Cortisol: is at its lowest around midnight and peaks around 6am
- Cortisol is our ' wake up' hormone
- they didn't t think that it would affect the circadian rhythm as natural day light would
- such as clocks and radios
- There where not isolated from artificial light
- Czeisler (1999)
- Altered participant circadian rhythm down to 22 hours and 28 hours by using dim lighting
- such as clocks and radios
- individual difference
- Evaluation
- Sleep wake cycle- Research method
- In all studies participants where isolated from variables that would affect their circadian rhythm
- such as clocks and radios
- There where not isolated from artificial light
- such as clocks and radios
- In all studies participants where isolated from variables that would affect their circadian rhythm
- Sleep- Circadian Rhythms
- Core body temperature
- Folkard (1977)
- Read stories to 12- 23 year olds at either 9 am or 3pm
- after 1 week the 3pm group ( higher body temp) showed better recall - up to 8% more meaningful material
- long term recall is best when the body temp is at its hightest
- after 1 week the 3pm group ( higher body temp) showed better recall - up to 8% more meaningful material
- Read stories to 12- 23 year olds at either 9 am or 3pm
- can be used to explain cognitive functions
- Gupta (1991)
- found performance on IQ tests were best at 7pm as opposed to 9am or 2 pm
- Folkard (1977)
- Cause or correlation?
- evidence suggests that temp changes does affect cognitive performances
- Glesbrech ( 1993)
- lowered participants body temp using cold water - found cognitive performances worsened
- Hord and Thomson ( 1983)
- did field experiment as opposed to lab and did find a correlation between core temp and cognitive functions
- Sleep wake cycle- Research method
- two types of individual differences
- cycle length
- Research has found that circadian cycles in different people can vary from 16 to 65 hours
- cycle oneset
- individuals are innately different in terms of when their circadian rhythm peaks
- Duffy (2000)
- found that morning people prefer to rise early and go to bed late
- 6:00am and 10:00pm
- evening people prefer to wake and go to bed late
- 10:00am and 1:00am
- found that morning people prefer to rise early and go to bed late
- cycle length
- Evaluation
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