Remembering to Sleep: Why and How Sleep Affects our Memory Processing

By Isabela Campos

The undeniable connection between memory and sleep is a topic that has been intriguing the realm of science for as long as the fields of neuroscience and psychology have existed.Although we once perceived sleep as an intermission to consciousness, further research on the concept has uncovered the deeply intertwined connection between sleep patterns and our ability to remember, learn, and engage in cognitive processing. ​ 

It is imperative to first understand the different kinds of memory that exist in the human mind. Our declarative memory—also known as our explicit memory—involves conscious intentional recollection of factual information such as an important date or a term from a textbook. On the contrary, implicit memory or non-declarative memory involves memories we don’t have to focus on retaining, like the procedure of walking. ​ 

In order to fully comprehend the connection between our sleep and memories, it is crucial to understand the stages of sleep and their distinct roles in the consolidation of our memories. The two main categories of sleep are non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM). Non-rapid eye movement sleep is further divided into four stages: Stage 1 and Stage 2 consisting of lighter sleep while Stages 3 and 4 consist of deeper, slow-wave sleeps. These four stages are usually where our declarative memory is consolidated. ​ 

REM sleep occurs much less often throughout the night and consists of rapid eye movement and brain waves during the time of rest. During REM sleep, implicit memories like how to play an instrument or ride a bike are strengthened and consolidated. In fact, further research shows that emotional memories are often also processed during this sleep stage, which potentially explains why emotional memories remain so strong in our memories. It is during REM sleep that we experience dreams. Shockingly, researchers have theorized that dreams are more than senseless representations of our subconscious. In fact, some studies propose that dreams help strengthen our memories, creating connection between new information and previously existing knowledge. ​ 

Further evidence of the connection between sleep and our memory and recall abilities is demonstrated when we analyze the effect of sleep deprivation of the recollection of memories. Chronic sleep deprivation leads to memory problems and has even been recently associated with the development of degenerative diseases such as Alzheimer’s. A short-term lack of sleep can also lead to issues retaining new information, which is why a good night’s sleep is always recommended when cramming for a big test or an important event. ​ 

Uninterrupted sleep cycles play a vital role in the consolidation of both sorts of memory, as it permits for both explicit and implicit memories to solidify in the mind. Waking up during a critical sleep cycle phase, such as REM sleep, can disrupt the memory consolidation process and lead to cognitive deficits. ​ 

This information is invaluable to today’s teenagers, who are often found staying up until dawn on our phones or cramming for an exam until the sunrise. Although it may not seem this way at first, chances are that getting a good night’s rest will actually improve your recall of information that one has learned.