Dreaming

REM and its traditional association to dreaming

What is REM sleep?

       REM sleep refers to the stage of sleep that we all experience approximately 90 minutes after falling asleep.  This stage of sleep typically follows the first four stages of sleep, which are known as non-REM sleep. REM sleep is characterized by the involvement of rapid eye movement, hence its name. This stage of sleep also involves muscle paralysis and cortical activation. And as will be discussed in more detail shortly, it often involves dreaming.

       REM sleep is also known as paradoxical sleep.  Beta activity, which is the electrical activity that typically occurs when one is awake, is commonly involved in REM sleep. It is because of the presence of beta activity that REM received its appropriate nickname. Also present during REM sleep is theta activity, which precedes beta activity in the sleep cycle. Theta activity usually marks the period between a wakeful state and drowsiness.  The presence of this characteristic also contributes to the infamously bizarre nature of REM sleep. Although its largely up to debate, REM sleep is thought to occur in order to allow the brain to further develop and to promote learning, memory and motivation. This may explain why we often feel unmotivated to learn or concentrate when we are lacking sleep.

EEG waves of beta activity	EEG waves of theta activity

Traditional association of REM sleep and dreaming

       Dreaming is traditionally associated with REM sleep. The connection between these two active brain states was first drawn from Eugene Aserinksy and Nathaniel Kleitman in 1953. Until more recently, the notion that dreaming occurs during REM sleep was widely accepted. The broad acceptance derived from the common observations that the occasional brain activation known to cause dreaming, or vivid images, occurred during REM sleep. Therefore, when first proposed, dream researchers largely supported the theory of dreaming and its association to REM sleep because it allowed for dream analysis to be regarded as scientific and could be explained, at least partially, by neurology.

So, why do we sleep…and dream?

       Currently, there are two principles that attempt to explain why we sleep.  Fundamentally, either sleep acts as an adaptive response to our environment or it serves as restoration for the mind.  The fact that all vertebrates sleep seems to imply that sleep occurs more as an adaptive response than to serve as rest for the mind.  However, slow-wave sleep, with its two deepest stages of sleep, appears to serve as a way for the body and mind to rest and recuperate.

       Research has shown that lack of sleep causes the inability for one to perform well on cognitive tasks. The same tasks are performed with much more proficiency when sleep has been acquired.  As mentioned earlier, REM sleep appears to possibly occur for brain development and thus, learning, memory and motivation.  Research has shown that REM sleep occupies most of babies’ sleep and considering this, it seems likely that REM may serve to allow for brain development to occur.  And although research has shown that REM sleep is not needed for the body itself – to perform its daily functions – the rebound phenomenon will occur if one fails to receive enough REM sleep.  The rebound phenomenon refers to the idea that a night’s sleep will be composed for more than its usual REM sleep if the previous night’s sleep didn’t involve enough.

How does the research on REM sleep relate to dreaming?

       In furthering the discovery of REM state as the dreaming state, other research set out to examine if dreaming existed as a means for survival. It was wondered if people who were deprived of sleep could continue to function normally.  Was dreaming necessary for our physiological well being like sleep appeared to be, or did it serve a psychological purpose? Like the research on REM sleep and the discovery of the rebound phenomenon, research showed that after a succession of dreamless nights, dreaming onset seemed to occur more rapidly after falling asleep and lasted for longer periods of time. In short, it seemed that our bodies tried to make up any dreaming that was lost over a succession of dreamless sleeps; it seemed our bodies were pressured to dream. The conclusion made from these research findings was that there must be some biological need for our bodies to not only sleep, but also to dream. On-going research is trying to pin the exact purpose for dreaming.