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Describe and evaluate research into the nature of sleep including lifespan changes
Research into the nature of sleep and its stages has been primarily carried out by Dement and
Kleitman (1950s) who carried out highly controlled investigations of sleep using EEG cans in sleep
The conclusions drawn from their research is that there are 5 main stages of sleep at night, whereby
stages 1&2 are characterised by alpha and beta waves which reflect relaxation and slow the body's
functioning. These two stages are known as `light sleep'.
Stages 3&4 are deep sleep characterised by delta and theta waves. This is known as Slow Wave
Sleep where it's proposed that the body undergoes reparation to its physiology.
The growth hormone is released during stage 4 of sleep. During this phase of sleep it is difficult to
wake someone up.
In the fifth stage, known as REM sleep, the brain and eyes are active but the body is paralysed. This
phase of sleep has been referred to as `paradoxical sleep'; Dement and Kleitman's research when
waking participants up in different sleep stages led them to believe that a person is dreaming in this
stage, because participants were more likely to report dreaming at this stage.
The progression between these 5 stages is known as a sleep cycle which lasts for about 90 minutes,
occurring several times throughout the night.
Dement and Kleitman's research into the nature of sleep can be praised on its methodology for using
highly controlled and objective EEG scans to determine what exactly is happening in the brain,
whereas preliminary research relied on whether a participants' eyes were moving or not.
On the other hand, this tool of measurement can make the results ungeneralisable because the
setting of the research was carried out in sleep labs which although highly controlled, it is low in
ecological validity because it's different to participant's beds and they might feel uncomfortable or
experience interrupted sleep, different to the results they might show at home.
With regards to how important their research is to science, it is regarded today as a valuable
pioneering discovery of the sleep stages which was made possible due to the development of EEG,
revealing that the brain is not simply `shut down' as previously believed.
The knowledge attained from Dement and Kleitman's research stimulated further research and
understanding of dreams and sleep disorders. This research can thus be interpreted as an application
into real life because better understandings of sleep disorders have helped a lot of people in terms
of pharmaceutical treatments for insomnia and other sleep related disorders.
On the other hand, there are individual differences which need to be addressed meaning that not
everybody follows the conclusions drawn from Dement and Kleitman's research because the sleep
stags apply to `average people'. Other research has indicated sleep changes with age and gender.
For example the proposed sleep stages may not apply to people with more demanding lifestyles,
such as a bodybuilder, because they might require more restorative sleep to match their bodily
requirements. As a result, the conclusions drawn from the research into the nature of sleep might not
apply to all people and treatments for sleep might not be effective for everyone.
This essay will also cover lifespan changes because as humans grow from infants to old age, there
are major lifespan changes in the amount and kind of sleep experienced.
Babies sleep for about 16 hours a day with a 70 minute cycle. They experience active and quiet sleep
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SWS and REM. They spend 50% of their time in REM sleep, and by 6 months
they have a circadian rhythm established.
During early childhood children sleep for about 12 hours a day with about 30% REM. Boys sleep more
than girls and it's not uncommon for children to experience a variety of parasomnias such as walking
or nightmares.…read more