However, it is not clear how this information would get to the SCN.
Light is considered to be the main zeitgeber in humans.
The importance of light as a time-giver can be seen in the difficulties observed in blind people.
Miles et al (1977) documented the problems of a young man who was blind from birth who had a circadian rhythm of 24.9 hours. He was exposed to various exogenous zeitgebers such as clocks and radios yet found great difficulity reducing his internal pace. This made it very difficult for him to function and as a result he had to take stimulants in the morning and sedatives at night in order to get his biological rhythm to co-ordinate his biological rhythm with the rest of the world. Therefore, this demonstrates that light really is the dominant time-giver.
However, there is also evidence that shows that where appropriate, light cues are disregarded.
Luce and Segal (1966) pointed out that people who live within the Arctic Circle still sleep for about seven hours despite the fact that during the summer months the sun never sets. In certain circumstances other external cues take over, such as social cues which dictate when it is time to get up and go to bed.
Evaluation
Support for the existence of an endogenous pacemaker that is reset by exogenous zeitgebers has been provided by Siffre (1972) who was removed from the normal light-dark cycle, by being kept in a dark cave for 2 months. There were no zeitgebers such as natural light or sounds and he had no idea what time it was. He had food and drink and so on. His behaviour such as when he slept/woke and when he ate his meals was monitored.
At first the findings showed there was no clear pattern in his sleep-waking cycle. However, later his sleep-waking cycle settled down to a regular pattern of about 25 hours i.e. longer the normal 24 hour cycle.
This suggests that our internal biological clock must have a 25 to 30 hour cycle and that that our zeitgebers must reset the clock to our normal 24 hour day.
Therefore, in conclusion the running of the biological clock is most likely to be a combined endogenous-exogenous exercise.
Both of the endogenous pacemakers and exogenous zeitgebers are important and both cause us difficulties.
In terms of importance, without a biological clock an animal’s behaviour would be totally determined by environmental cues. This could be life-threatening as there would be no regularity to their behaviour. For example, Decoursey et al (2000) destroyed the SCN in some chipmunks and found that these animals were much more active at night than the normal chipmunks and were more likely to be taken by night-time predators.
On the other hand, having inbuilt biological rhythms can be problematic because they wont change when we want them to. For example, think of the difficulties people experience when working shifts. Darkness tells them they should be asleep. Also, think of the difficulties related to jet lag, the light tells us we should be wake but our internal clock says its time for sleep.
Disrupting Biological Rhythms
Environmental factors influencing our biological rhythms tend to change slowly, allowing the endogenous pacemakers to keep up.
However, if the exogenous zeitgebers change quickly, problems can occur such as poor attention and slow reaction time. These can arise from two features of modern life; shift work and jet lag.
Shift Work
In shift work, employees are required to work when they would normally be sleeping and they would sleep when they were normally awake. Switching between day and night shifts disrupts links between external zeitgebers (day/night) and biological rhythms.
Czeisler et al (1982) studied the effects of shift work.
He found evidence of health problems, sleep difficulties and work-related stress in staff employed in short rotation shifts.
This would imply that changing to longer shift rotation should reduce the ill effects of shift work.
Czeisler et al introduced this for two years and found that productivity increased, there was a marked improvement in job satisfaction and there was less sick time.
This is supported by Monk and Folkard (1983) who stated that the internal/external discrepancy can be reduced by rapidly rotating shifts.
Also, the effect of short rotation shifts has been applied to the cause of industrial accidents that have occurred, such as Chernobyl.
Arendt et al (2005) studied the role of melatonin in shift work. He studied shift workers on oil rigs, for men working a split-shift pattern.
He found, their levels of melatonin did not become synchronised to new sleep times after shift changes.
This suggests that their shifts disrupted their circadian rhythm.
An application of this is Sharkey (2001) who found that the use of melatonin could speed up adjustment to shift patterns.
However, in 1997, US guidelines concluded that research on melatonin was insufficient to recommend it as an aid for shift workers.
An alternative explanation to reduce the effects of shift work has suggested by Dawson and Campbell (1991) who found that exposing workers to artificial light appeared to help them work better.
Jet Lag
Jet lag is caused by a sudden disruption of the body’s circadian rhythms as a result of travelling across time zones. The body clock is thrown out of ‘sync’ if it experiences daylight and darkness at the wrong times in a new time zone, as a person’s body will still be working to the original rhythm.
Klien et al (1972) claimed that jet lag is more severe when you fly from West to East, than from East to West because the traveller must adjust to losing hours (phase advance) rather than gaining them (phase delay).
This is supported by a study carried out by Schwartz et al (1995). He analysed the results of west coast baseball teams who travelled east (phase advance) and found they had fewer wins than east coast teams travelling east to west (phase delay).
However, other studies have looked at the effects of jet lag on athletes and found the findings to be inconclusive.
This suggests that performance is not badly affected, providing motivation is high.
Bre (2001) studied the effects of jet lag.
He showed that the main effects of jet lag were; desynchrenisation of circadian rhythms, difficulties of getting to sleep and reduced alertness and concentration.
However, findings on mental performance were inconsistent, varying across studies.
This is possibly due to confounding variables such as differences in motivation.
Also, other studies have looked at the effects of jet lag on athletes and found the findings to be inconclusive.
This suggests that performance is not badly affected, providing motivation is high.
One suggestion to combat jet lag is to use melatonin to reset the body clock.
Takahashi et al (2002) studied the role of melatonin on jet lag. He found that the administration of melatonin speeds up the resynchronisation of body rhythms after a long flight and it helps to reduce the symptoms of jet lag.
Sleep Deprivation
Sleep deprivation also disrupts our biological rhythms.
This is supported by the study of Peter Tripp.
Peter Tripp took part in a wakeathon which lasted 200 hours.
He managed to stay awake for the whole 200 hours, however he suffered from serious delusions, hallucinations and his body temperature dropped dramatically.
This shows that sleep deprivation can have serious, negative effects on someone’s physical and psychological wellbeing.
However, the following criticisms have been made in relation to the study.
The study only concentrates on one individual, therefore it may only relate to the characteristics of the unique individual i.e. individual differences.
This implies that the findings cannot be generalized to all human behaviour.
This study has also been supported by Horne (1988) who looked at the case of Randy Gardner who stayed awake for 264 hours.
He also concluded that sleep deprivation has negative effects when Randy suffered from blurred vision, slight paranoia and disorganised speech at the end of the 264 hours.
However, even though Randy Gardner stayed awake longer than Tripp, he was clearly less affected by sleep deprivation.
Therefore, this suggests there are individual variations.
b) Sleep
Sleep must serve some function. If not it is difficult to explain the fact that we spend approximately one third of our life’s in a state of sleep.
Theories of Sleep
Several theories of the function of sleep have been proposed.
Restoration theory
One of these is the Restoration theory suggested by Oswald (1980).
The physiological system is of primary concern in this theory.
If physiological restoration is the function of sleep we would expect that sleep deprivation would have serious effects upon an individual because physiological restoration was prevented.
We would expect animals who use more energy to sleep more and that more sleep would be required after periods of physical exertion.
The main assumption of the Restoration theory is that sleep enables the body to make physiological repairs and save energy after the exertions in the day.
Thus, without sleep an animal’s health (physical/mental) would deteriorate i.e. they also say that sleep may serve to restore psychological functions.
Oswald (1980) claimed REM sleep enables brain recovery.
This can explain why there are high levels of brain activity seen during REM sleep. He also stated, that Slow Wave sleep (SWS) enables body repair.
This is supported by the fact that there is a significant increase in the body’s secretion of a growth hormone during SWS.
Oswald’s claims are supported by the findings of his study he conducted in 1969.
He observed patients recovering from drug overdoses or other brain insults.
He found that all the brain insults were followed by a significant increase in the quantity of REM sleep. This suggests that this was due to recovery processes going on in the brain.
Other support for Oswald’s theory has come from studies of newborn babies.
Green (1994) supported the view that REM sleep is essential for brain restoration.
He did this by citing evidence that new born babies (who experience enormous brain growth) spend a very high proportion of their time asleep devoted to REM sleep (50-60%) in comparison to adults who spend under half the amount of time (25%).
An implication of the restorative function of sleep is that increased physical exercise should lead to increased sleep in order to restore the energy lost.
This is supported by Shapiro et al (1981) who studied runners who took part in an ultra marathon covering 57 miles.
He found the runners slept about an hour and a half longer than normal on the 2 nights following the ultra marathon.
Further evidence for the Restoration theory comes from sleep deprivation studies, which investigate the effect a lack of sleep can have on an individuals psychological functions.
Berry and Webb (1983) conducted a study in which they assessed self-reported anxiety.
They found that when people slept well during the night, their level of anxiety was lower than when they had slept poorly.
In support of this, Naitoh (1975) discussed various studies concerned with the effects of one nights sleep deprivation on mood.
The effects were found to be consistently negative.
Sleep deprived individuals described themselves as less friendly, less relaxed and less cheerful than those who had not been sleep deprived.
The evidence provided, supports the view that lack of sleep causes a depressed mood and increased anxiety.
This therefore suggests that sleep has a role in the recovery of some psychological functions.
However, we’ve got to take into account that individuals may differ in how they react to lack of sleep. Some people may cope better than others. Therefore, these results may not apply to the population as a whole.
Moreover, conflicting evidence has been conducted by Rosenzweig et al (1999) which challenges this theory.
They studied the effects of energy expenditure.
They gave participants intense energy expenditure during the day.
If Oswald’s claims were correct this should increase the duration of sleep in order to restore the resources used.
However, they found intense exercise does not cause people to sleep for longer.
Furthermore, to challenge the idea that sleep is necessary for bodily restoration, Horne and Minard (1985) gave participants exhausting tasks to see if this increased the duration of their sleep.
His results showed participants went to sleep faster, but not for longer.
Evaluation
Overall, there is a considerable amount of support for the Restoration theory.
It provides a logical approach which implies that the more energy you expend the more you look forward to going to bed.
Sleep deprivation studies have also had important implications on the theory and provide evidence that sleep improves an individual’s mood and health.
Such as Everson et al (1989) who found that prolonged sleep deprivation in rats increased their metabolic rate, lose weight and die.
In contrast, death was prevented when the rats were allowed to sleep.
This implies that sleep is essential in relation to an individual’s physical and mental state.
Nevertheless, with this study it is difficult to separate the effects of sleep deprivation and the methods used to keep the animals asleep i.e. constant stress.
However, there are inconsistencies in relation to the Restoration theory.
We can argue that if sleep does have a restorative function we would expect that people who are more active would require more sleep.
But we have seen the research evidence does not support this view i.e. Rosenzweig et al (1999).
Furthermore, there is need for multi-perspective evidence that explains sleep as a psychological and physiological function.
Also, the Restorative theory doesn’t explain why there are so many differences in the way animals sleep. It may be that sleep serves an ecological function instead.
Ecological theories
Ecological theories take the view that sleep is an adaptive function.
They presume that sleep occurs in all animals because it promotes survival and reproduction.
Predator Avoidance
Meddis (1975) proposed the predator avoidance theory which claims that the function of sleep is to keep animals inconspicuous and safe from predators at times of the day when there are most vulnerable.
For most animals, this means sleeping during the hours of darkness.
It follows that those species in danger from predators should sleep more of the time than those species that are predators.
However, Allison and Cicchetti (1976) pointed out that in fact predators tend to sleep more than those preyed upon.
This might seem inconsistent with ecological theories of sleep.
However, species that are in danger from predators might benefit from remaining alert most of the time and sleeping relatively little.
Interesting evidence which supports the claim that the pattern of sleep is often dictated by the environmental threats faced by animals was reported by Pillieri (1979).
Dolphins living in the River Indus are in constant danger from debris floating down the river.
As a consequence, these dolphins sleep for only a few seconds at a time to protect themselves from debris.
Further evidence which supports this theory has been reported by Allison and Cicchetti (1976).
They studied the relationship between sleep taken by animals and the degree of danger typically experienced by that species.
In 39 species, the amount of sleep taken by an animal correlated negatively with the amount of danger typically experienced.
This indicates that the greater the environmental danger, the less time an animal spent sleeping per day, as predicted by the predator avoidance theory.
However, there are exceptions. For example, rabbits were found to sleep as much as moles, but rabbits had a very high danger rating whereas that of moles was very low.
In addition, the data is correlational, rather than demonstrating a causal relationship between sleep and predator avoidance.
Hibernation theory
Webb (1982) suggested a different ecological theory, called the hibernation theory.
Warm blooded animals (like ourselves) need to use a lot of energy to maintain a constant body temperature.
This is particularly problematic for small animals with a high metabolic rate (metabolism referring to the chemical processes occurring in the body).
All activities use energy and animals with a high metabolic rate use even more energy than for example, foraging (looking for food) or escaping from predators.
According to Webb (1982) sleep serves the purpose of providing a period of forced inactivity (therefore using less energy), much like hibernation is a means of conserving energy.
In support for this theory, research has compared sleep patterns in different species and found that the percentage of daily life occupied by sleep varies according to the size (and hence metabolic rate) of a species. The amount of sleep is further modified by other factors such as foraging and predator avoidance.
Moreover, research obtained by Zepelin et al (1974) supports Webb’s claims.
They studied the relationship between sleep length and metabolic rate across 53 mammalian species.
They found a negative correlation between body size and total sleep time, indicating that animals with higher metabolic rates sleep for longer. Small animals spend more hours a day asleep, while larger animals sleep relatively little.
For example, they found that animals such as the elephant sleep for fewer than 4 hours a day, whereas the little bat sleeps 20 hours a day.
This research shows that an animal’s metabolic rate and size are related to sleeping, as predicted by the hibernation theory.
However, this relationship is not true in al species. For example, Sloth’s are very large and slow so they should not need much sleep, yet they sleep 20 hours a day.
Evaluation
Overall, the ecological theories of sleep offer an explanation of why there is such a variety of sleep patterns within the animal kingdom.
However, there are problems with applying this theory to human sleep.
Empson (1989) calls ecological theories a ‘waste of time’ because they propose that sleep happens in order to waste time.
However, sleep deprivation studies do suggest that lack of sleep has distinct consequences.
For example, et al (1989) found that prolonged sleep deprivation in rats increased their metabolic rate, lose weight and die.
In contrast, death was prevented when the rats were allowed to sleep.
This implies that sleep is essential in relation to an individual’s physical and mental state.
It may be that sleep serves a restorative function instead.
Overall evaluation
In evaluation, according to the restoration theory sleep is absolutely essential to well-being.
In contrast, sleep is generally less crucial according to ecological theories.
There are no reports of human beings who have managed without sleep.
However, Meddis, Pearson and Langford (1973) argue that there are few reports of individuals who have led normal healthy lives in spite of regularly sleeping for very short periods of time each day.
Horne (1988) made the important point that sleep probably serves different purposes in different species. Thus, no single theory of the functions of sleep is likely to be adequate.
However, it could be argued that these two explanations address different issues, with the restorative approach providing why sleep is important and the ecological approach focusing on when different species sleep.
c) Dreaming
Dreaming mainly occurs in REM sleep and takes the form of highly, vivid dramatic stories of a visual nature.
The Nature of Dreams
Most dreaming takes place during REM sleep, so we can therefore use the duration of REM sleep during the night as on approximate measure of how long an individual spends dreaming.
It also means we can consider what other physiological activities are taking place at the same time to try and find out why people and other animals dream.
We know that animals have REM sleep because for example, dogs show evidence of twitching in their sleep as if they were chasing something.
However, we have no way of telling what their personal experiences actually are.
In humans we can ask people to tell us about their dreams, though again we don’t know to what extent their recall is distorted by the fact that they were asleep.
The fact that we spend so much time devoted to dreaming suggests that dreams are likely to fulfil some important function or functions.
Various theorists have tried to identify these functions.
Dement and Kleitman (1957) sought to demonstrate a link between REM activity and dreaming, to help research into dreaming.
If REM sleep is dreaming than we might expect dreams to be specific to REM sleep, the duration of REM activity and the individual report of dreaming to be similar and the movement of the eyes to be related to the visual memory of the dream.
Nine adults took part in the study.
Typically, a participant reported to the sleep laboratory just before their normal bedtime and went to bed in a darkened room. Electrodes were attached around the participant’s eyes (to measure eye movement) and to the participants scalp (to record brain activity as a measure of depth of sleep).
At different times during the night a bell rang and woke the participants up. They were woken either randomly or during alternations of REM and NREM activity. On average participants were woken 6 times a night.
The participant then spoke into a recording machine by their bed, saying whether they had been dreaming and if so describing the content of the dream. An experimenter was listening outside the room.
Dement and Kleitman found that participants had REM activity every night, which lasted between 3 and 50 minutes. During that time the eyes showed bursts of activity.
Interestingly, there were individual differences in the intervals between REM activity. The average was once every 92 minutes.
Most dreams were recalled when participants were woken from REM sleep, but some were reported when participants were woken from NREM sleep.
When participants were awoken during deep sleep they were sometimes bewildered and reported that they must have been dreaming, though they couldn’t remember the dream. They only recalled a mood such as anxiety or pleasantness, but no specific content.
Dement and Kleitman estimated the length of the dream in terms of the number of words the participants used to describe the dream or to ask the participant to estimate the length. Both were positively correlated with the length of REM activity.
There did appear to be some support for a relationship between eye movement and activity. For example one participants displayed horizontal eye movements when they were asleep and they dreamt they were watching two people throwing tomatoes at each other.
Evaluation – Dement and Kleitman
A key criticism of Dement and Kleitman’s study was its artificiality, that it took place in a laboratory, therefore sleep activity may not have been true to real life.
Futhermore, the fact that participants were awoken during the night might have affected their behaviour, especially when you consider the effects of sleep deprivation.
For example Dement (1972) reported the case of Peter Tripp who aimed to go without sleep for 8 days.
After a couple of days Tripp’s behaviour changed and he became verbally abusive and tired. He suffered hallucinations and showed severe signs of paranoia.
At the end, Tripp’s brainwaves patterns had changed and every 90 minutes his hallucinations became more severe like waking dreams or nightmares.
Nevertheless, this research did provide some useful data about dreaming, although it did not find an exclusive link between REM activity and dreaming and doesn’t tell us anything about the purpose of dreaming.
Dreaming and Consciousness – the nature of dreams
Empson (1989) identified the features of dreaming in comparison to waking consciousness.
First dreamers, typically feel they have little or no control over their dreams, whereas we nearly always have a sense of consciousness control in our waking lives.
However, some people have lucid dreams, in which they can sometimes control their dream content.
This is supported by LaBerge et al (1983) who studied a woman who was able to create lucid sex dreams that produced orgasms.
Second, dreams often contain elements that seem illogical in our waking consciousness. For example, dreams often contain impossible events or actions and can also include various hallucinations and delusions.
Third, we tend to be totally absorbed by our dreams imagery. However, when we are awake, we can usually stand back from our conscious thought and avoid being dominated by them.
Theories of the Functions of dreaming
Neurobiological and Psychological theories have been proposed, which explain the function of dreaming.
Neurobiological theories
Neurobiological theories try to explain the function of dreaming through intense neural activity during REM sleep.
Reverse learning theory
The reverse learning theory proposed by Crick and Mitchison (1983) claims that we dream to forget.
The theory suggests that the brain is ‘offline’ during dreaming.
This enables it to sift through all the information gathered during the previous day, and discard any parasitic (unwanted or irrelevant) information.
This stops the unwanted information disrupting the efficiency of memory and means that the brain does not fill with useless details which they suggested it couldn’t cope with due to its limited storage.
Research Evidence
Blakemore (1988) supported Crick and Mitchison’s view of the function of dreaming.
He investigated the physiological processes involved in dreaming and the elimination of unwanted information.
He claimed that ‘Dreams are quite literally, a kind of shock therapy, in which the cortex is bombarded by barrages of impulses from the brainstem below, while a different mode of synaptic modification ensures that the unwanted elements of each circuit are elliminated’
Crick and Mitchison claimed that the size of the cortex in different species of mammals provides support for their theory.
They pointed to the fact that the only mammals not having any REM sleep associated with dreaming are dolphins and spiny anteaters. This would lead one to presume that these species are therefore unable to get rid of useless information.
According to Crick and Mitchison, these species only manage to function effectively because they have unusually large frontal cortexes for mammals of their size, so they therefore have no need to discard useless information.
However, it has been argued that the human cortex is much more highly folded than the dolphin or spiny anteater, therefore it may just have as much capacity.
Alternatively, Winson (1997) put forward an alternative explanation which claimed that the large cortex allows the mammals to cope with performing the clearing operations at the same time as the daily processing tasks while awake.
This therefore removes the need for REM activity.
Evaluation
The reverse-learning theory represents an interesting approach to dream function. It explains why we rarely remember the content of our dreams.
However there are inconsistencies in relation to this theory.
It doesn’t explain why some dreams are often organised into a clear narrative (i.e. stories) or have a meaningful content, as it fails to clarify why this should happen if dreams consist simply of disposable, parasitic thoughts.
Crick and Mitchison later restricted the reverse learning model to apply only to dreams with bizarre imagery and no clear narrative or meaning.
This theory is challenged by Modern connectionist ideas which suggest that the brain has a vast potential for information storage and there is no need to save space.
Furthermore, there is evidence that foetuses engage in something resembling REM sleep. This implies that foetuses are trying to forget meaningless information before they are even born, which many psychologists find hard to believe.
There is also an issue into question of REM and NREM sleep. The theory only describes one basic explanation of the function of dreams, but does not explain why this would to several physiological states (NREM activity). It might be that other kinds of activity in NREM are synthesised.
This leads to the conclusion that the theory may be to reductionist to fully explain the function of dreams and may only provide partial explanations of dreaming and may only be related to REM activity.
Activation synthesis theory
Hobson and McCarley (1977) put forward the activation synthesis theory which argues that dreams are merely the brain's reaction to random biological processes that occur during sleep.
The theory suggests that during REM sleep, all sensory input and motor output (bodily movement) are blocked, so that we experience sleep paralysis and external stimuli are prevented from entering our brain.
Yet the neurons in the cerebral cortex are still activated by random sensory impulses.
The forebrain attempts to make sense out of this internally generated information as if it was produced by external stimuli and this leads to the experience of dreaming.
Research Evidence
Braun et al (1997) used PET scans to show that the brainstem is active during REM sleep. This gives support to the activation part of the activation synthesis model.
Hobson (1988) provided further physiological evidence to support the activation synthesis theory. Research on cats indicated that there is apparently random firing of cells in cat’s brains during REM sleep. This then produces activation in parts of the brain that are used as visual perception and control of motor movements.
However, movement is restricted in REM sleep so the body interprets the information by other means, dreaming.
However, the activation synthesis model has been challenged by Solms (2000) who studied case histories of brain damaged people (when people sustain damage to there brain stem), REM activity almost always finishes but dreaming continues.
Hall (1966) reviewed 815 dream accounts and found only about 10% had unusual contents. So the activation synthesis theory's claim that dreams are bizarre and illogical is not supported.
Futhermore, Vogel (1978) has shown that dreams of REM sleep can occur in the absence of REM sleep i.e. dreams can arise without the brainstem activation produced by REM sleep.
Evaluation
The activation synthesis theory deserves credit because it is based on detailed information of the physiological activity of the brain during dreaming.
The theory can explain why smells and tastes rarely appear in our dreams .i.e. because only those parts of the brain involved with vision and hearing are activated.
It also accounts for the incoherent nature of many dreams, but can’t explain why dreams sometimes possess a clear meaning and coherence.
Also it can’t explain why dreams often relate to current concerns if they are based on random activity. Thought it might be that any synthesis that takes place draws on past experiences and therefore becomes meaningful to the dreamer.
Evaluation of neurobiological theories
Neurobiological theories see dreams as an accidental by-product of neurobiological processes.
The theories have been criticised because they provide no explanation for why some dreams have meaning beyond the possibility that our cognitive processes have a tendency to impose meaning on any set of data.
There is also an issue into the question of REM and NREM sleep. Both theories describe one basic explanation of the function of dreams, however they don’t explain why this would apply to several physiological states. It might be that other kinds of activity in NREM are synthesised.
We can probably at the best conclude that these accounts of dreaming are partial explanations, and may only be related to REM activity.
Psychological theories
The function of dreaming also has psychological explanations which challenge the above neurobiological theories
Psychoanalytic theory
Freud (1900) suggested the Psychoanalytic theory which claims that dreams contain wish fulfilment.
A key assumption of Freud’s theory of dreaming was that dreams represented the disguised fulfilment of desires repressed into the unconscious mind. Such wish fulfilments are often unacceptable to the dreamer when they are awake. This leads to the dreamer to produce separate manifest content (what the dreamer actually dreams) and latent content (the true meaning of the dream).
According to Freud dream analysis provides a royal road to understanding the unconscious mind.
Psychoanalysis can be used to uncover the latent content of dreams partly through the interpretation of universal symbols, for example dancing representing sexual intercourse.
But, according to Freud it is more likely that many dreams are based on personal symbols rather than universal interpretation.
In one case, he analysed a patients dream about a wiggling fish. The patient suggested this may represent a penis. However, Freud concluded that in fact the dream represented the patient’s mother, who was a passionate astrologer and Pisces i.e. astrological sign for a fish.
This case supports his claim and implies that many dreams require careful individual interpretation based on personal symbols rather than universal interpretation.
However, the efficacy of psychoanalysis is open to question because some psychologists are not certain that it works.
Research Evidence
Hajek and Belcher (1991) showed that dreams are related to current concerns.
They studied the dreams of smokers who were involved in a programme designed to help them stop smoking.
They found that most of the participants reported dreams focused on smoking during the course of the treatment and for a year afterwards.
In the dreams, engaging in smoking was followed by feelings of panic or guilt.
Such dreams seemed to help ex-smokers; those who had the most dreams and most guilt about smoking were less likely to start smoking again.
However, these findings are correlational and do not show that the dreams were actually useful.
But, Hawkes (1999) findings support Freud’s theory. He found that dream content reflected unconscious wishes in brain damaged patients.
Evaluation
Freud deserves credit for putting about the first systematic theory of dream function in a repressed 19th century society.
It was appropriate in the time at the time it was written and implies that some of his patients were probably experiencing wish fulfilment due to repressed desires.
The theory has been influential in discovering the function of dreams.
In addition, Freud argued that dreams can provide us with vital information about unconscious thoughts and about the way the dreamer is feeling. Most later theories have been unwilling to go that far, however they have accepted that dreams can tell us something about the thoughts and feelings of a dreamer.
Moreover, the theory explains the fact that dreams often reflect our current concerns.
There is little empirical evidence to support Freud’s claims about dreams. The theory is challenged by Hobson and McCarley (1977) who argued that dreams are simply an artifact of brain activity during sleep, and therefore have no real meaning or emotional content. This view is markedly different from Freud’s view that dreams represent the fulfilment of unconscious desires.
Freud’s theory has been criticised in relation to the time he lived in, when many feelings were repressed, whereas today it is improbable that there is as much repression in today’s liberal and permissive society. However, Hayes (1994) pointed out that if dreams have a wish fulfilment function, then we would expect in today’s society that people would find a stronger food and eating content within their dreams.
Furthermore, there are additional problems with this theory. The theory doesn’t explain why some dreams are not wish fulfilling, such as frightening nightmares.
Also, the latent content of a dream is open to question because even though some dreams may represent wish fulfilment, it is unlikely that all dreams can be regarded as wish fulfilling.
Another criticism of the Psychoanalysis theory is that it ignores physiological processes involved in dreaming and only focuses on the psychological explanations.
Problem solving theory
Webb and Cartwright (1978) proposed the problem-solving theory which claimed that dreams are a way of working out personal and work problems.
There are many well known examples of this, such as the chemist Kekule who dreamt of a ring of snakes that revealed to him the ring like atomic structure of benzene molecules.
Like Freud’s wish fulfilment theory, the problem solving theory also suggests that dreams are a way of coping with problems.
However, in the problem solving theory, the manifest content of the dream is the true meaning of the dream, although the dream may rely on a metaphor, such as the ring of snakes.
Research Evidence
Webb and Cartwright (1972) described a study which provides support for their theory, in which participants were given problems to solve and then allowed to go to sleep.
Some were then woken when they entered REM sleep.
They found those that had been allowed to sleep uninterrupted were able to provide more realistic solutions to the problems the next day, suggesting that there REM sleep had given them the opportunity to work through their problems.
In another study Cartwright (1984) interviewed women who were undergoing divorce and were either depressed or not depressed. He then compared them with a non-depressed married group who has never considered divorce.
All participants were studied over a 6 nights in a sleep laboratory.
The non-depressed divorcing women reported having longer dreams which dealt with marital status issues. This apparently helped the individuals cope better.
Such issues were absent from the dreams of the depressed groups. Presumably the depression was associated with an inability to deal with problems
The above findings are supported by Hartmann (1973 who found that people who were experiencing various kinds of problems had more REM sleep than the less troubles individuals.
Evaluation
The problem solving theory seems to be a reasonable account of dreaming and is supported by some research studies.
However, this approach doesn’t explain why people and animals have dreams not related to the solution of problems.
Also, the problem solving theory implies that it would be useful to remember our dreams. But, it seems puzzling that we forget about 95% of our dreams.
There is also the question of why sleep is necessary because we can also solve problems by engaging in another task for a while, as indicated by the saying ‘a change is as good as rest’.
The most reasonable conclusion is that the problem solving theory helps to explain some dreams, but does not provide a comprehensive account of all dreams.
Finally, this approach is uninformative about the physiological processes involved in dreaming.
