Forgetting Dreams: The Science Behind Not Remembering Dreams

Sriya Gullapalli | Assistant Editor

Dreams: they are intense, picturesque, and lucid all in one small interval of time. However, despite their vivid and overt nature, many individuals report their inability to recall any details or even the presence of a dream a few hours following them. As a result, there is one quintessential question that remains after observing a large subset of persons: why do some remember their dreams while others are unable to? In order to answer this question, it is necessary to first consider the current understanding or research of dreams as well as the science behind the concept of dreams, then dive into when dreams precisely occur, before finally noting the ‘how’s’ and ‘why’s’ some individuals are unable to recollect them.

In the fields of neuroscience and psychology, the topic and experiments of dreams is a subject area that piques the interest of many scientists. Indeed, the remarkable notion that individuals are seemingly asleep and are fully disconnected from the world of conscious experiences and the tangible environment, yet can subconsciously generate graphic images and a self-constructed, abstract universe – or in other words fabricate a dream – is an idea that still requires research and engenders interest. In simple terms, dreams are hallucinatory experiences that abide by a narrative and sequential structure. Analysis and numerous developmental studies have attempted to extend the understanding of dream phenomenology. More specifically, brain lesion studies, functional imaging, and neurophysiology have paved the way for the understanding of the neural basis of dreaming. Due to the past and ongoing research, it is possible for individuals to merge different areas of research and answer key questions, such as how conscious experiences in sleep correlate to brain activity, how and why the dreamer is greatly unaware of the external environment, and whether dreaming is more closely associated with perception or mental images.

Empirical scientific evidence points that individuals often experience full-fledged dreams primarily during rapid eye movement or REM sleep. However, it should be noted that dreams can also occur during non-rapid eye movement or NREM sleep. The narrative of dreams gradually begins during slow wave sleep, or SWS, early in the night, where consciousness progressively disappears despite the continuing persistent neural activity in the thalamocortical system.

Despite the dreams’ sheer vividness that individuals experience during REM sleep, many mention the inability to remember those dreams the morning that follows. Although there are several explanations for this occurrence or rather absence, the most cogent explanation is the absence of an important hormone in the cerebral cortex: norepinephrine. Norepinephrine is a bodily hormone that is responsible for modulating memory and remembering as it can regulate synaptic mechanisms in areas such as the prefrontal cortex. Interestingly, during the time of one’s dreams, this hormone exists in very low levels. Thus, it is this low presence of norepinephrine during dreaming which is the prime reason why one cannot remember their dreams just the subsequent day. Furthermore, a study published in 2002 in the American Journal of Psychiatry affirms the theory that the presence of norepinephrine enhances memory in humans. While the lack of norepinephrine explains partly why individuals forget dreams easily, the story does not finish there. Recent research suggests that dreaming lies on the same spectrum as many other forms of mental functioning that work within the cerebral cortex. While one side of the spectrum is centered in focus and centralized thought, the other end includes dreaming and mind wandering with some overlap. The side of the spectrum that is of interest in understanding the reasoning behind why most dreams cannot be recalled by the human mind is the side concerning dreams and mind wandering. This end involves some of the most inventive, creative, and foreign material. In other words, the dreaming end is frequently considered unconscious or indirect thought. For instance, consider the thoughts an individual has while eating breakfast or driving. Though this thought is the main focus while the activity is actively being performed, it is very difficult to recollect those same thoughts later on in the day. Akin to the thoughts individuals have throughout their day that do not require much focus or instructed attention, dreams also vanish due to this subconscious and unfocused thought the brain inherently directs towards it during their occurrence. However, it is interesting to note that particular dreams that are impressively beautiful or idiosyncratic to an individual’s subjective mind may be more likely to be remembered. These dreams are likely to capture an individual’s attention and increase activity in the dorsolateral prefrontal cortex, or DLPFC, which is a subsection in the brain that controls higher cognitive functions including selective attention and working memory. Moreover, dreams that also have a greater logical consistency or a reasoned plot have a greater probability in being remembered. In addition, the time of awakening in relation to the completion of one’s dream (i.e. awakening seconds after a completion after a dream in contrast to hours following) also seemingly plays a role in the ability to recall dreams.

Dreams are of chief interest to many scientists and common individuals across the world. Nevertheless, the deeper reasoning and science behind them and the role of various body systems in relation to them is still of ongoing research. Although there are still countless inquiries of the physiological and psychological function of dreams, it is interesting to examine why certain individuals recollect dreams while others fail to. Perhaps not every dream may be recollected; however, marking and examining the ones that are remembered may suggest something about an individual and their inner thoughts. Indeed, it just takes some overnight sleep and some self-discovery to become more aware of one’s unaware dreams.

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