Table of contents
- Biological Approach (Dement & Kleitman, 1957)
- Cognitive approach
Restoration theory (Oswald, 1966)
Reorganizational (Crick & Mitchison, 1983)
Sleep is defined as the state when your body is reduced in consciousness and your body is less responsive to the external world. We go through 5 different stages throughout the night. The first is a light sleep as you are drifting off and it lasts 5-10 minutes. The second includes a deeper sleep as your brain waves slow and sleep spindles show up on an EEG (used to check your brains activity). The body’s temperature and heart rate reduce. Stage 3 occurs after 25 minutes and delta waves occur, gradually increasing. Stage 4 is an even more profound sleep and if woken you would become groggy and disorientated. The final stage is different from the rest - REM sleep. This occurs 90 minutes into sleep and is the point in your sleep when you are found to dream. The body is a lot more active during this stage, at the point of wakefulness. The body is also relaxed and steady. REM stands for ‘rapid eye movement’ meaning your eyes show bursts of movements under your eyelids during this stage. The main differences between non-REM and REM, is the type of sleep you are in and what regulates these stages. Sleep is also needed for concentration. Sleep deprivation has found to be linked to a reduction in memories. People who are sleep deprived have worse immune systems, meaning they are prone to catch illnesses. Caffeine and amphetamine are stimulants which make people more alert and less tired. After consuming these people may struggle to sleep. This is due to a naturally occurring hormone in our brain called adenosine which block the receptors in our brain, causing drowsiness. We need less sleep the older we get. Infants need 18 hours of sleep per day and spend half of this time in REM sleep. The developing brain requires a great deal of protein synthesis. This replenishes and renews brain processes for cell manufacture and growth, REM sleep helps achieve this.
Biological Approach (Dement & Kleitman, 1957)
Dement and Kleitman (1957) investigated REM sleep to find out if it was related to dreaming. After studying participants overnight and waking them up at different parts throughout their sleep, they found 80% of the participants reported to have been dreaming during the REM stage. This shows the eye movements in sleep are connected to dreaming. Our internal body clock controls our circadian rhythm. The SCN (suprachiasmatic nucleus) in our hypothalamus in the brain receives light information and releases melatonin that makes us sleepy. Dreams only appear in the final stage of sleep – REM sleep. Biological psychologists believe dreams are meaningless and just a side effect of the brain's activity during sleep.
This approach is very scientific, and researchers use proper methods which ensure the reliability and makes it practical. The approach also provides obvious examples that are proved with scientific evidence, meaning many experiments support these theories. However, the biological approach is not very generalised and does not consider other influences on behaviour such as emotions, social pressures, or childhood experiences. The approach also focuses on humanism and you cannot compare animals to humans.
Restoration theory (Oswald, 1966)
This theory approaches sleep by stating that it is necessary for the body to rest and recover. During sleep, the body heals small damages, the abolish of unneeded chemicals in muscles and restores neurotransmitters in the brain. It is also said that non-REM sleep replenishes the bodies physical factors and REM restores our brain and mental actions. This approach explains how our brains reinforces our memories as we sleep and how it eliminates parasitic memories. It also gives reasons as to why we dream. The approach is limited, and we likely sleep for more reasons than just physically restoring our body. Another negative thing is it often being compared to computers. The brain is much more intricate than that.
The evidence of this was found in a study of runners by Shapiro et al. (1981) where they found the sleep had by the runners was extended by 90 minutes than usual over the two nights of an ultramarathon. They learned it was their non-REM sleep that lengthened, rising from 25% to 45% of total sleep. This supports the idea that the body needs sleep to repair itself.
Adam and Oswald (1983) found that hospital patients who have undergone spinal operations or drug overdoses engaged in longer periods of REM sleep, supporting this idea of sleeping to restore your bodily functions.
This approach looks at the role of sleep in memory and thinking. It goes by that the mind is a processor of information and sleep exists to help this processing. Cognitive psychologists believe sleep is for memory consolidation, putting them in logical order and removes parasitic memories. The mind clears up the files, prunes unnecessary items and strengthens links between memories. The concept of schema is used to explain this approach. During memory consolidation, similar memories seem to reactivate in a pattern, suggesting they are being ‘linked’ in the brain. The continuity hypothesis of dreams suggests dream content is based on what we have been thinking about. REM strengthens newly formed connections in the brain, which helps learning and memory foundation (especially helps declarative memories). NREM is associated with the consolidation of declarative memories (facts, dates, events). Wagner et al (2004) shows that challenging maths problems are easier to understand after sleeping. This approach believes dreams to be what happens when the brain needs a task to do. It has strong points as it explains what our brains do with memories while we sleep which is good. It is very scientific and has lots of studies to prove it. Dreams are more likely to contain information related to an individual's current concerns. Despite these points, it does not explain why dreaming happens in the frontal part of the brain. It also does not explain that if dreaming is purely about consolidation and problem solving, why do you dream about things that have not or are not going to happen.
Reorganizational (Crick & Mitchison, 1983)
This theory focuses that the brain requires memory consolidation to work correctively. Therefore, in our dreams, we are sleeping to reorganise and improve memory storage. This theory follows the concept of reverse learning - we dream to forget - meaning learning can be undone during REM sleep. They believe dreams are just a side effect of our brain decluttering parasitic (unwanted) memories during REM sleep. The other category of memories which they believed us to have are adaptive (wanted) memories. Therefore, you cannot always remember your dreams, as they hold images our brain has already ‘deleted’ the connections to. An example that backs up this theory is the spiny anteater which does not REM sleep, but instead has an enlarged frontal cortex. Crick and Mitchison believe this larger area is used to store parasitic memories. The pruning during REM allows for a more efficient brain. However, most research shows sleep to be helpful to memory, rather than the contrary. This theory also does not explain as to why our dreams often make sense to us and have a story to them – only to then be destroyed.
Czeisler et al (1990) examined night shift workers’ and whether their alertness and sleeping would improve with light-dark reversal treatment. Many problems arise due to shift work, including sleep deprivation, poor alertness, mistakes at work, risk of heart disease and emotional issues like anxiety or depression. Major industrial disasters have become more frequent such as Chernobyl in early hours due to fatigue, memory loss, reduced productivity, and low staff morale. The experimenters exposed shift workers to treatment involving bright light at night hours and complete darkness during the day at an attempt to prevent disturbances to circadian rhythms involving the sleep-wake cycle.
The study aimed to find a routine, including light exposure, which would improve shift workers to fully adapt to daytime sleeping. Czeisler and his colleagues applied this treatment to eight healthy males all in their 20’s, none of which had previously been shift workers. This was important to ensure their circadian rhythms were not messed with already. The shift work was mimicked in a laboratory location at night. There were five control and five treatment studies conducted in all. Involved were two conditions, the first being for night shift workers in a control condition with low-level lighting of 150 lux. In this condition, the men were asked to use their home setting for any daytime sleeping they needed. For this, sleeping was left unregulated and naturalistic. Secondly, an experimental condition under bright illumination of 7000-12000 lux (equivalent to early morning light) was conducted with the participants daytime sleeping at home was treated to having opaque windows and artificial darkness enforced. The participants were asked to stay in complete darkness from 9am to 5pm and wear sunglasses if necessary. They were needed to report their moods and alertness after completing the 6-day experiment. Czeisler and his team found disturbances and sleep wake cycle including associated declines in alertness performance and quality of daytime sleep can be treated effectively with scheduled to exposure too late at night and darkness during the day.
This study has led to the design of special light treatments for shift workers, jet travellers and those with sleep disorders. However, the sample size of this study is exceedingly small and only looks at men making it difficult to generalise the undivided population of night shift workers. Another weakness includes, they did not account for peripheral variables like what the participants had for breakfast or if they had a coffee for example, making it difficult to recognise if they contributed to the outcome.