Biological Approach Flashcards
Evolutionary Theory
Key points
Sleep theory
Meddis 1975
Periods of activity and inactivity
Conserve energy and avoid predators
All species have adapted to sleep during periods of time when wakefulness would be most hazardous
Evolutionary Theory
Strengths
Animals with lots of predators sleep 4/5 hours a day (shrews/mice)
Animals with few natural predators sleep 12/15 hours a day (bears/lions)
Evolutionary Theory
Weaknesses
Humans no longer need to hide from predators
Empson (1993) criticises: even predators need sleep, a single explanation cannot account for all animals
Restoration Theory
Key points
M
Sleep theory
Adam and Oswald 1983
Body carries out repairs to cells
Keeps energy and helps remove waste chemicals
Brain can rest and restore supplies of brain proteins and neurotransmitters
Restoration Theory
Strengths
Babies need a high proportion of REM sleep to help with growth
Zager et al (2007) deprived rats of sleep, there was a decrease of 20% in white blood cells
Restoration Theory
Weaknesses
Horne’s study (1978) studied 50 humans who had been sleep deprived,
he found sleep deprivation did not interfere with participants ability to perform an exercise
Activation Synthesis Theory
Key points
Dream theory
Hobson and McCarley 1988
Dreams are random internally generated signals from the brainstem
Dreams may be personal, but are meaningless
Bizarre dreams occur when there is a lack of info, so the brain does its best to give meaning to them
Activation Synthesis Theory
Strengths
Pet scans: brain stem and frontal lobe are active - prefrontal cortex is inactive
Explains why dreams are without smell, this part of the brain is inactive
Hobson found acetylcholine is the firing agent in the brainstem, when acetylcholine is injected R.E.M. and dreaming occurs
Dement and Kleitman 1957
Aim
To investigate the relationship between eye movements and dreaming
Dement and Kleitman 1957
Hypothesis (3)
1- significant association between R.E.M. sleep and dreaming
2- significant positive correlation between length of dreams and eye movement
3- significant association between pattern of eye movement and the dream
Dement and Kleitman 1957
Method/Procedure (5)
Studied under laboratory conditions
9 participants to eat normal (no caffeine/alcohol)
Sent to bed in quiet, dark room
EEG used to record signals
Awakened during the night to recall dreams
Dement and Kleitman 1957
Results
1- R.E.M. sleep linked to dreaming, Non R.E.M. was non dreaming
2- The participants recall times of sleep and dreaming
3- Context was linked to eye movement
Dement and Kleitman 1957
Conclusion
Strength: dreams studied in objective way, opening areas of research
Weakness: mostly men, lack of generalisability
