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Biology 103
2002 Second Paper
On Serendip

The Biology of Dreams

Heidi Adler-Michaelson

"Just as dreams are unreal in
comparison with the things seen in waking life, even
so the things seen in waking life in this world are unreal in
comparison with the thought-world, which alone in truly real."- Hermes

Since the beginning of their existence, heterotrophic organisms have been defined by the need for sleep. Humans accept it (more or less willingly) when they are infants and embrace every opportunity for it as college students and adults. It does not take a lot of psychological or biological background to tell that it is critical to human life. Our bodies simply stop functioning after a long period of time without it and the more we get the better we feel. But what if sleep is not only necessary for the body but the mind as well?
This is the origin of the dream. If one studies the fundamentals of biology she is sure to learn that nothing exists if it is unnecessary for survival because it would have regressed over the course of billions of years. What then is the importance of sleep to the human mind? One might think that sleep is the same as being unconscious but people take sleeping pills to knock themselves out and wonder why they still feel horrible or even worse the next morning. In fact, sleep is full of mental activity. During sleep muscles tense; blood pressure, pulse, and temperature rise; and various senses are alert (4). Random thoughts occur throughout the night, sometimes even taking on some scheme. This phenomenon is called a dream.
What is a dream? It would be pretentious of anyone to assume that modern psychology or biology have grasped all the complexities of dreams. Yet, especially in the past two centuries, many theories stand and observations have been made. There are at least three indicators that someone is dreaming.
The first indicator is called rapid eye movement (REM) sleep. As the name indicates, the eyes of the sleeper move back and forth at rapid speed during her sleep. If one is to wake someone up indicating this rapid eye movement, the sleeper is sure to tell of the vivid dream(s) she just experienced (4).
The second indicator of dreaming has to do with the EEG (electroencephalogram) system. If one takes a closer look at a sleepers brain wave pattern in REM sleep, there are striking similarities to the pattern at an awake stage (7). It consists of desynchronized minimal waves in both cases (3).
The third indicator that someone is dreaming is if they are paralyzed. In fact, paralysis is thought to protect the dreamer from acting on their dreams. This paralysis is due to certain neurons in the frontal lobes of the brain. The activity of the brain during this stage of sleep begins in a structure called the pons which is located in the brain-stem. The pons send messages to shut off the neurons in the spinal cord which results in an almost full body paralysis (2).
The first REM session occurs c. 90 minutes after falling asleep and then in 90 minute intervals after that. Depending on how long one sleeps, she can have between four and six REM sessions each night. (2).The first session is very short no longer than five minutes. Each succeeding REM session get longer and the average person's longest dream can be up to thirty minutes long. (1).
Psychology has made some early advancements in the subject of dreams dating back to the Austrian neurologist who developed Psychoanalysis: Sigmund Freud. His theories have oftentimes been taught as the truth which is always a problem. His successors today believe that dreams serve as mental relief and problem solving. In the past decades, however, biologists have made considerable advances in the field of dreams. They state that the most important function of dream sleep is the growth of the brain. This is a result of the observation that infants dreams four times as much as adults. Neurobiologists have discovered that "neurons (brain cells) sprout new axons and dendrites (nerve fibers) during dream sleep. This brain growth gives us a stronger network of brain circuits which allow us to have greater intellect...Although many brain chemicals are involved in sleep and dreaming, two very important ones are the neurotransmitter serotonin and a brain hormone called melatonin. Both are produced by the pineal gland of the brain" (1). Melatonin is meant to calm the brain and induce sleep. Serotonin on the other hand triggers the brain to dream.
Since I wrote about the effect of alcohol on the fetus in my last paper, I thought it might be interesting to consider the effect it has on sleep and dreams. The neurotransmitter, as I hope I've made quite clear, is crucial to the dreaming process. Alcohol causes the level of Serotonin in the brain to drop considerably which results in what appears to be dreamless sleep. This is sleep without REM activity. On the other hand, when alcoholics try to withdraw, many experience delirium tremens (DTs) (2). These nights are characterized by shaking, sweating and hallucinations. Many biologists believe that the mind takes the opportunity of the absence of alcohol and overproduces serotonin which results in the hallucinations.
It is important to understand that not sleeping can be harmful on at least two levels and can lead to hallucinations while one in awake. Generally one's body will compensate for lack of dream sleep one night by dreaming more the following night until the normal quota is reached. Unless you are an alcoholic who does not sleep in which case you will quite literally "loose your mind" (2).
As with any field of science, there is a fair amount of controversy surrounding dreams, some of which has been presented already. Furthermore, as with any field of scientific research, it is safe to assume that the controversy will never end. There are many theories but one in particular I would like to concentrate on. David Maurice, Ph.D. is a professor of ocular physiology in the Department of Ophthalmology at Columbia-Presbyterian Medial Center. He is one of the many that questions the wide-spread belief that REM sleep exists mainly to process memories of the previous day. Maurice hypothesizes that "while sleep humans experience REM to supply much-needed oxygen to the cornea of the eye...[He] suggests that the aqueous humor—the clear watery liquid in the anterior chamber just behind the cornea—needs to be 'stirred' to bring oxygen to the cornea." In addition he states that "[w]ithout REM our corneas would starve and suffocate while we are asleep with our eyes closed" (5).
The reason for Maurice's engagement in this field of study began some years back when he started observing animals. He says: "I wondered why animals born with sealed eyelids needed REM or why fetuses in the womb experience a great amount of REM" (5).
David Maurice then developed his hypothesis after learning about a young man who had an accident and whose eyes had been immobilized as a result. His corneas had become laced with blood vessels to supply the corneas with oxygen. We know that when eyes are shut, oxygen can reach the cornea from the iris solely by way of the stagnant aqueous humor. Maurice did the calculations and found that the oxygen supplied under these conditions would be insufficient. This ultimately formed his hypothesis that REM must bring oxygen to the brain somehow.
As I indicated in the beginning, the functions of dreams are still unclear and heavily under debate. Dreaming may play a role in the restoration of the brain's ability to cope with tasks such as focused attention, memory, and learning. Dreaming may "just" be a window to hidden feelings. Almost everything is possible and we may never know. We do know that "You have, within yourself, an ability to make yourself experiences no one else has ever had. And hence to see things no one has ever seen and learn things no one has ever learned" (6). Maybe it is as important to individualize dreams as it is to analyze the general population's dreams. We might just by able to learn about ourselves and in the process, learn about others as well which the beauty of science is, after all. Whether the thought is soothing or uncomfortable, as you continue to sleep and dream you must know that the controversy of the biology of dreams is one that won't ever go to sleep.


1)Geocities Biology Page, a rich resource from Geocities
2)21st Century Biology, a rich resource from by Lauren Brownlee
3)General Psychology I- Introductory Psychology, a rich resource from the University of Connecticut
4) Ask A Scientist, a rich resource from United States Department of Energy
5)Columbia University Biology Page, a rich resource from Maury M. Breecher
6)Serendip page, a rich resource from Bryn Mawr College
7)Sleep Stages from upenn, a rich resource from the University of Pennsylvania

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