Sleep and Consciousness

Functions of REM and NREM

During rapid eye movement sleep is the time when new information is processed and stored into our memory banks. Our personal experience of this very important brain function is dreaming. A world is created. When you're in a dream it feels real. Even if you know it's a dream at the time it feels real. If you jump up in a dream and you fall down you feel the thud. Although when you wake up, you realize "oh well, that was a dream" and then tend to minimize and dismiss it, but the feelings of it's reality are there during the dream.

So how come whoever put this system together, God, nature, whatever, made this time when we are hallucinating so much that we think it's real. We're having all these emotions. All this bizarre stuff is going on. Our body is responding like mad while we are paralyzed from the neck down. Furthermore if we weren't paralyzed there is good evidence that we'd get up and act out the dream. Recently in Toronto a man got up from bed in the middle of the night, got into his car, drove across town, and killed him mother-in-law. A colleague of mine testified at the court case. He took him to his sleep laboratory in Boston and monitored the Toronto man's sleep He told me there is no doubt, it is easy to identify as can be seen in Figure 1. You can see that muscle tone has flattened out in REM but in his REM the muscle tone did not flatten out. He had muscle tone. Enough to murder.

The point is, if we didn't have that paralysis we'd act out our dreams. Can you image acting out your dreams? Maybe your dreams would be okay but some of my dreams, I don't know! So how come this thing called REM is there? There is all this activity on a biological level. From the intra-psychic, heavily psychodynamic level, all my inner self, unconscious motives and drives or all my "junk" is in there. That combination sounds interesting all by itself. We have some idea of how these things develop and Figure 3 gives you some indication of it. If you look at the percent of waking as we go through the life span from infancy and birth through childhood and adolescence to adulthood and old age you see it increases. Along the horizontal axis are the daily sleep and waking requirements. You can see that in infancy there are huge amounts of REM sleep relevant to the rest of your life. We certainly know newborn infants sleep a lot, that the older you get you sleep less and less and thus you have less and less REM sleep.

These data give us some hint as to the functions of REM and NREM sleep. Very briefly these are: information processing for REM whereas the function of NREM is somatic, vegetative maintenance. In other words NREM restores the body. For instance, growth hormones peak during delta sleep. Delta sleep is the deepest NREM sleep. So children not only have to get enough sleep, they've got to get enough delta sleep. Delta sleep tends to occur early in the sleep cycle. There's a disorder called social dwarfism where there is a failure to grow, children with it are unusually small. It was called "social" cause no biological mechanism could be discovered but they found that among failure to thrive children there was a high incidence of family dysfunction. There was a lot of stress and tension in the family. It may be that the children's sleep cycles are being disrupted enough so that there was not enough growth hormone being released during delta.

Another piece of evidence that supports the vegetative restorative function of NREM sleep is when there is high pre-sleep metabolic rates they are associated with higher levels of delta sleep. So if you're working on getting your metabolism up you are going to need more delta sleep. Also higher brain functions appear to be somewhat reduced during delta sleep. Slightly less brain oxygen consumption and as noted psychological events related to it are sparse.

REM sleep plays a role in the reorganization, restoration of brain processes that mediate the flow, structure and storage of information. This includes things like problem-solving, memory consolidation, information processing, and creativity. About 50% of the sleep cycle of the newborn is REM or quasi-REM kinds of sleep. Newborns sleep 16 to 20 hours a day. That is eight hours of REM! A reasonable question is, "What are they dreaming about, after all they were just born?" Although one could get metaphysical and talk about past lives it's not really necessary.

It turns out that when an infant is born although they have all their brain neurons, the communicating aspect of the neuron, the synapse which connects neuronal cells, have just begun to grow about a month before birth. Without the ability to communicate with each other the neurons are virtually useless. There are enough synaptic connections at birth for some basic survival behaviors. For instance, a newborn will recognize their mother's voice at birth and can see with perfect visual acuity for about 8 inches, the distance to mothers face as nursing but not beyond, which would be confusing and disruptive to the bonding process with the mother which must occur for the newborn to ensure its survival. Still there are a lot of neuronal connections to be made. After all getting that thumb in the mouth without poking ones eye is a fairly major task particularity when mom's not around. Learning to coordinate visual input, thumb, with motor output, moving it to mouth, takes synaptic connections. This growth of the synapses probably occurs during REM sleep. Because the newborn has so much to piece together in terms of simply getting all the potential motor activities working properly, among many other tasks, it is no wonder that they need huge amounts of synaptic growth time or REM. Along the same lines a premature infant will show as high as 75% rapid eye movement sleep.

Other evidence pointing to this cognitive function for REM is with the right hemisphere. Although the right-left hemisphere dichotomy has been over simplified, there is relatively more activity in the left than in the right hemisphere of the brain during the day. What happens at night is not that the right hemisphere takes over rather it increases activity to the level of the left hemisphere. Therefore the kind of information that is best processed in the right hemisphere in conjunction with the left hemisphere is going to happen in the main during REM.

On a psychological level REM may serve some compensatory process function as hypothesized by Freud. Personally important experiences may be repressed during the day and thus you'll see a reciprocal emphasis in dreams at night. More often than not, however, you'll see a continuity between presleep experiences and dream experiences of the REM or NREM sort. What you've been thinking about before you go to bed at night, you'll see in the dream of that night. This is especially evident in our children. When my son was about 8-years-old we were impressed with the advertisements for a movie about cute little "Gremlins". Naively we went to the theater but during their first transformation with water into sharp toothed small but lethal monsters we both high tailed it out to the lobby. Not surprisingly that night about 2 a.m. I felt a small body crawl into bed with me. The "gremlins" from the show had awoken him from a nightmare!

But to simply reduce dreams to meaningless rough reproductions of waking events is also to reduce their importance. Most dreams occurr during the time of the sleep cycle when we process new information into our memory banks, REM sleep. Therefore dreams are always autobiographical and unique to each individual.

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