Why Do We Dream?
There are many opinions on what a dream is; according to Colman (2009), dreams are mental experiences, usually sequences of ideas, images and imagined events, sometimes containing emotions, which occur during REM sleep.
Freud (1921, as cited in Biopsychology, 2008) believed that dreams were the result of unacceptable repressed wishes. He thought that the dreams which we experience are disguised by an unconscious censor so that we are able to tolerate them without being disturbed (Freud, 1921). A downfall of this work however is that there has been no empirical evidence which can be used to back this theory up (Biopsychology, 2008).
Hobson and McCarley (1977) believe that the bizarre elements in dreaming may be due to the properties of the pontine brain stem neuronal generator mechanism. The activation-state model proposes that the information which is supplied to the cortex in REM sleep is mainly random, therefore the dream which forms from this information is the product of the cortex attempting to make sense of these random signals (Hobson and McCarley, 1977). Implications of this model are that the main motivating force for dreaming is physiological rather than psychological, as the time which dreaming occurs and the duration of the dream tends to be relatively constant (Hobson and McCarley, 1977). This suggests that dreaming is neurally determined, rather than due to psychological factors (Hobson and McCarley, 1977). Also, particular stimuli which occur in the dream imagery seem to occur randomly from the pontine brain stem, rather than the cognitive areas of the cerebrum (Hobson and McCarley, 1977). This gives the idea that the dream process is not due to factors such as emotion, as Freud (1921) suggested, but rather due to sensorimotor stimuli (Hobson and McCarley, 1977). This activation-state model of dreaming contradicts Freud's (1921) idea of the distortion of unacceptable wishes with the use of a censor, as it implies that the structures in the forebrain are involved in a process of self-activation beginning where the dream is created in the pons (Hobson and McCarley, 1977).
Hobson et al. (2003, as cited in Manica, 2005) since suggested that in the visual centre of the brain, hallucinations occur due to self-activation, due to the output in the pons. This also triggers the parietal cortex, which is needed in order to give spatial organisation to the dream (Hobson et al., 2003). Through activation of the amydale by other limbic and paralimbic structures, emotions are part of the dream (Hobson et al., 2003). Occurrences in the dream such as loss of self-awareness, delirium and illogical experiences are caused by aminergic de-modulation and inhibition of the dorsolateral frontal cortex (Hobson et al., 2003). These new findings caused Hobson et al. (2003) to change the earlier concept, stating that during dreaming the mind is simply the self-activated brain.
In contrast, Stickgold, Hobson, Fosse and Fosse (2001) are of the view that dreams reflect the activation and recombination of memories; that they emerge from waking memories. They propose that a key factor in the function of the brain whilst dreaming is emotion, consequently meaning that the brain is biased towards emotional processing whilst in this state (Stickgold et al., 2001). This is due to the fact that in REM sleep the central nucleus of the amygdala plays a critical part in the activation of the medial prefrontal cortical structures, linked with the highest order regulation of emotions (Stickgold et al., 2001).
Another theory by Hobson (2004, as cited in Revonsuo, 2000) is that dreaming in REM sleep could have a purpose in memory consolidation through rehearsal of motor programs; however dreaming which contains vivid phenomenal content simply reflects totally unrelated events occurring at other levels of organisation in the brain, where they could possibly be serving useful neurobiological functions.
Crick and Mitchison (1983) proposed a new idea of the function of REM dream sleep; that during wakefulness the cortical system, which holds a huge array of modes of excitation, is bound to also have unwanted modes. The theory holds the view that these unwanted modes are sought out and removed by a mechanism which can only operate during REM sleep, this being an active process called reverse learning; this nonsense information is then expressed as dreams (Crick and Mitchison, 1983). Since the majority of dreams are not even remembered, it is suggested that forgetting is a necessary part of the process (Crick and Mitchison, 1983). Crick and Mitchison (1986) developed their theory further with new evidence to defend criticisms received, in which they point out that erasing unneeded connections will have the effect of improving cognitive structures; this fits in with Hobson and McCarley's (1977) hypothesis that REM dream sleep has a positive function on the learning process.
Foulkes (1982) put forward a cognitive-psychological model of dreaming, based on data and models from other cognitive disciplines, which he supposed were relevant to dreaming, as REM dreaming is a cognitive act which requires skill. Although the input and output processes of speech and dreams are largely dissimilar, it was proposed that the processing involved could be indistinguishable (Foulkes, 1982). The aim of this work was to show how dreaming can be approached as a process rather than a content perspective; currently there is not enough evidence to back up this theory, but it may be used for future modelling (Foulkes, 1982).
More recently, Foulkes (2002) published work which indicated that dreams are more than simple perceptual phenomena; they are predominantly a way of thinking, resulting from random activation and reorganisation of the components of memory. This therefore implies dreaming depends on a persons ability to access and cognitively process recent experiences, knowledge and other memories (Foulkes, 2002).
Cipolli, Bolzani, Tuozzi and Fagioli (2001) implemented an experiment in which it was assessed whether a sleeper can control the processing of recently acquired knowledge during sleep. It was found that if a nonsense sentence was heard before sleep, when subjects were awakened during REM sleep and asked to remember their dream experience and the last sentence heard, recall was higher than when the sentence actually made sense (Cipolli et al., 2001). This finding implies that cognitive concern influences the accessing of recently obtained knowledge; helping to consolidate this knowledge by making it more likely to be processed during sleep (Cipolli et al., 2001).
In the dream psychology theory of dreaming, the focus is on the individual's psychological adaption to current waking life; that dreaming occurs to help the individual to cope with or solve present issues in their life, therefore promoting psychological well-being (Revonsuo, 2001). This theory can be split into two categories; the first one that dreaming has a problem solving function in an intellectual aspect, and the second one that its function is linked to emotional adjustment (Revonsuo, 2001). Barrett (1993) carried out an experiment in which the subjects were asked to choose a problem to try to solve in their sleep every night for a week. Around half of the subjects recalled a dream which was related to the chosen problem, with the majority of these believing that the dream contained a solution (Barrett, 1993). Looking at the problems concerned, issues which were of a personal nature were far more likely to be solved than ones of an academic or general issue (Barrett, 1993). This does imply that the function of dreams may be to problem solve on a personal level, however an issue with this research is that personal problems have less defined solutions than that of other issues; consequently this may mean a bias in what can be classed as a solution. The fact that the majority of dreams are not remembered raises an issue with this theory though; surely if the purpose of dreams was to solve problems, they would be recalled.
Hall (1966) proposed the idea that dreams reveal peoples views of themselves, other people, and also how they feel about other people. He also thought that dreams are not simply impulses; but that they show attitudes towards impulses (Hall, 1966).
Jung (2001) believes in a built-in mechanism called individuation, which is a process necessary in order that we can become psychologically healthy; it is the incorporation of the conscious with the unconscious. Dreams are part of this process, as they act as a communicator to create a balance of emotional well being; if an imbalance occurs Jung (2001) believed that psychological disturbance is probable. Jung (2001) built on Freud's (1921) ideas, and although he did believe in wish-fulfilment through dreams, he did not believe that wish-fulfilment should be the sole principle in interpreting dreams. Jung (2001) stated that dreams entail many things such as illusions, truths and wild fantasies; for them to be useful to us, we should use them to finish off revelations from within the dream, rather than look back to the cause of the dream. He thought that dreams could present prospective potentials of the future, but not absolute predictions (Jung, 2001).
Similarly, Parker (2006) considers that there is much more to dreaming than just randomness, as many dreams are not just nonsense. Dreams seem to be related to either a balance or imbalance in our emotional being, in a way which can sometimes be interpreted whilst in a conscious state to have meaning, however mostly they could be described as messages in a code (Parker, 2006).
Todman (2008) looked at the idea of inspirational dreams; which have been cited as the foundations of creative ideas, looking at two examples in the field of neuroscience. Otto Loewi and John Eccles both allegedly had dreams which lead them to scientific discoveries, establishing chemical synaptic transmission (Todman, 2008). Both of the examples occurred whilst the researcher's minds were highly focused on their unsolved problem, for which the breakthrough came in their dreams (Todman, 2008). Todman (2008) proposes the idea that the brain may have a capacity to process information in a different way during sleep, as a pose to during waking.
However, Flanagan (1995, as cited in Revonsuo, 2000) rejects the idea that dreams have any biological function, believing that dreaming is simply a side effect of other functions the brain is performing during sleep. He puts forward this theory, not only as he thinks that phenomenal experience during dreaming has no adaptive worth as the functions of REM sleep and PGO waves do not require any mental activity, but also as he believes that dreams do not even seem to be worth remembering the majority of the time (Flanagan, 1995).
Antrobus (1993) is of the same view, as he believes that since during REM sleep no sensory information is processed, and no association-motor commands are implemented, it has no effect over what the association cortex does; also, as it has no maladaptive consequences, dreaming has been able to survived evolution even though it has no merit. He also states that if dreaming contains useful information which should be considered during consciousness, then surely those who have no recall or pay no attention to dreams should suffer disadvantages relating to their personality or mental health, but this is not the case (Antrobus, 1993).
Having considered a variety of different explanations in relation to why dreaming occurs, it has become clear that there has not yet been a theory which has enough evidence behind it to be taken as the definite answer. Some theories believe that dreaming is a useless side effect of other processes occurring in the brain, whilst others think that dreaming is useful in maintaining psychological well-being; however none of the theories looked at have any empirical evidence to back them up in order for simply one of them to be accepted. For a dependable conclusion to be reached this would be necessary; until then it can only be assumed that dreaming is a mysterious, complex process which cannot, as of yet, be understood.
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- Stickgold, R., Hobson, J. A., Fosse, R., & Fosse, M. (2001). Sleep, Learning, and Dreams: Off-line Memory Reprocessing. Science, 294 (5544), 1052.
- Todman, D. (2008). Inspiration From Dreams in Neuroscience Research. The Internet Journal of Neurology, 9 (1)