Neuroscience explains why we fail to remember most sleepy adventures
Humans find escapism in many forms, whether it be music, films or books. However, one form that is commonly neglected but available to all is the extraordinary journey that we embark upon in the realm of sleep. Dreams have the power to serve as a vivid canvas for the imagination, transforming the ordinary into the exceptional. Nevertheless, most of them slip away from our memory like morning mist. Due to this fading nature, many intense dreams carrying deeper meanings are forgotten as soon as the morning light shines through the window.
To explain this phenomenon, one has to first understand why we forget things in general. Oliver Hardt, an assistant professor of psychology at McGill University, says that forgetting is important as it allows us to filter and retain important information. Inconsequential and redundant information is forgotten through our brains’ conscious attempt. Without this process, “each time you want to think about something”—something key to your survival, such as the location of food or the signs of an approaching predator—“all these memories would pop up that are completely meaningless and that make it hard for you to actually do the job of predicting what is next,” Hardt said.
A general explanation for loss of dream memory provided by Ernest Hartmann, professor of psychiatry at Tufts University School of Medicine and director of the Sleep Disorders Center at Newton-Wellesley Hospital is that dreams often carry information that we regard as unimportant. Information carried in dreams is similar to those unimportant pieces of information in everyday life, like the way your socks feel when you pull them onto your feet and the shirt color of a stranger passing you in the street.
Similar to this theory, another study has implied that dreaming is on a continuum with other mental processes, all of which are characterized by cerebral cortex activities. Focused thought is on one end of this continuum, while daydreaming and mind wandering are on the other, with some overlap between the two. Some of the more imaginative and "far-out" content is found in the dreaming/reverie end which is much more difficult to recall.
Other explanations involve complex neuroscience operations. For example, scientists theorized in the American Journal of Psychiatry in 2002 that the lack of norepinephrine, a hormone important for memory, cognition, language and awareness, in the cerebral cortex leads to the diminishment of memories. Paul Frankland who runs the Josselyn Frankland Neurobiology Lab at Toronto’s Hospital for Sick Children explains his theory involving the loss and gains of memory: with faster neurogenesis, or the formation of new brain cells, in the hippocampus comes higher probability of memory loss. This is backed by the observation of a graduate student who noticed that mice with more brain cells learned mazes faster but were also more likely to forget the structures of mazes they had mastered previously before their brain growth.
Although many explanations exist, it is clear that the loss of dreams is due to a conglomerate of neuroscience factors including the nature of memory, the function of the hippocampus and brain hormones like norepinephrine. The fact that our brains are wired to prefer reality to fantastical adventures furthers the mysteriousness and complexity of this phenomenon that is still open to research.
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