Functions of sleep- evolutionary explanation
- Created by: Hannah Jeffery
- Created on: 16-02-15 10:07
View mindmap
- Functions of sleep- evolutionary explanation
- Lesku et al
- looked at the complexity accounts for the range of sleep patterns in the animal world
- anomalies
- sloth is a relatively large animal but sleeps for 20 hours a day
- correlational studies
- cannot establish cause and effect
- difficult to distinguish between correlations and IV's
- herbivores have to graze many hours a day so have less time to sleep
- however, they're also prey animals and so want to diminish risk to predators
- difficult to establish which factor is more important
- Factors according to the evolutionary ecological approach
- body mass
- large animals sleep less
- Brain mass
- more REM sleep
- animals with exposed sleep sites
- sleep less
- herbivores sleep less than carnivores
- body mass
- observational research for about 54 species
- approach takes in ecological and physiological factors
- cannot be regarded as reductionist because it explains sleep in terms of the whole animal and its environment
- high ecological validity
- Allison studies sleep in 39 species
- prey animals sleep for significantly less time than predators
- Meddis believes that sleep leaves an animal unreactive and vulnerable
- if safety was the only consideration then sleep would not exist
- anomalies such as rabbits have a high danger rating but sleep as much as turtles which have a low danger rating
- Meddis believes that sleep leaves an animal unreactive and vulnerable
- prey animals sleep for significantly less time than predators
- hibernation/ energy conservation
- Basal metabolic rate (bmr) -the rate of energy consumption- is positively correlated to sleep
- Lima and rattenberg
- small animals have a higher BMR than larger animals and so they sleep more
- Basal metabolic rate (bmr) -the rate of energy consumption- is positively correlated to sleep
- Energy conservation
- warm blooded animals (mammals) need a lot of energy of maintain a constant temperature
- sleep serves the purpose of providing a period of enforced inactivity and uses less energy
- warm blooded animals (mammals) need a lot of energy of maintain a constant temperature
- keep out of the way of predators
- Meddis et al
- animals can hide themselves in the dark and not draw attention to themselves
- Siegel also concluded that it reduces injury
- NREM and REM
- energy conservation only drops in NREM
- Cicchetti found that larger has less NREM sleep but not less REM sleep
- further argument that primitive animals such as most reptiles only have NREM sleep
- REM sleep evolved more recently and may of been to maintain brain activity
- while NREM sleep might of been evolved first for energy conservation
- Capellini
- criticised previous research for not having standardised date collection methods between species
- meta- analysis of studies only using standardises procedures
- eg lab conditions or habituated animals
- found a negative correlation between metabolic rate and sleep
- smaller animals have higher metabolic rates and sleep less
- disproves energy conservation theory
- but supports foraging being a main factor into sleep
- higher metabolic rate or low energy diet decreases sleep time
- predators sleep more but also species who sleep socially also sleep more
- Unilateral sleep
- sleep patterns can be an adaptive response to selective pressures
- this is when only one half of the hemisphere of the brain sleeps
- for example dolphins need to swim to the surface frequently for a breath
- a dolphin the feel into SWS would drown
- the two hemispheres of the brain swap over every two to three hours
- allow the dolphin to survive without disturbing sleep patterns
- for example dolphins need to swim to the surface frequently for a breath
- evolutionary approach
- fails to incorporate sleep deprivation
- horne
- proposed that we have core and optional sleep
- core is vital sleep that is required for the body and brain functioning
- optional is REM sleep and is dispensable
- occupies unproductive animals and conserves energy
- combines elements from evolutionary and restoration approach
- proposed that we have core and optional sleep
- Lesku et al
Similar Psychology resources:
Teacher recommended
Comments
No comments have yet been made