Sleep is the dominant state of consciousness for most higher animals. Most animals, such as dogs, cats, bears, snakes, etc. spend more time sleeping than being awake.
Sleep is not the same as being unconscious. When a person is unconscious, such as being in a coma, there is little or no mental activity occurring. However, sleep is full of mental activity. We have random thoughts and ideas occurring throughout the entire sleeping process. What psychologists describe as dream sleep is when this mental activity becomes vivid, intense and takes on some theme.
In the 1950's psychologists discovered that there were periods of time during sleep in which the eyes of the sleeper would dart rapidly back and forth. They called this rapid eye movement sleep or REM sleep. They discovered that if they woke a sleeping person during REM sleep, the sleeper almost always reported that they were dreaming. Therefore REM sleep became known as dream sleep, and rapid eye movements are an indicator that a person is dreaming. Non-rapid eye movement sleep is when the person is not dreaming. Although NREM sleep is not classified as dreams sleep, it is full of random mental activity.
There are two other indicators of dream sleep. There is a specific EEG (electroencephalogram or brain wave pattern) that only occurs during REM sleep. If a person is connected to an electroencephalograph (called an EEG machine--a machine that detects and records the electrical activity of the brain) and the person's brain starts to emit this specific brain wave pattern, wake the person and they will report that they were dreaming.
A third indicator of dream sleep is paralysis in the large muscles of the body. This probably serves to protect the dreamer so that they cannot act on their dreams. Certain neurons in the frontal lobes of the brain cause this paralysis. If these neurons are destroyed, you get an organism that attempts to act on their dreams. Often one dreams that they are being attacked, but they feel that they cannot move. This perception occurs because of this paralysis.
For the average person on the average night the first session of REM sleep occurs about 90 minutes after falling asleep. These REM sessions are repeated about every 90 minutes, giving the average person 4-6 REM sessions each night. The first REM session is very short, lasting no longer than five minutes. The succeeding REM sessions get longer. However, the average length of a mid-sleep dream is only about 25 minute.
Many people believe that their dreams last longer than this. What happens is that you dream something during one REM session, think about it during NREM sleep, and pick up the same theme in successive REM sessions. This gives the person the perception that they dreamed about the same theme for a long period of time. The longest REM session is the last one before waking. This session lasts an average of about 30 minutes.
So for the average person the longest dream is about 30 minutes. However, there are two isolated exceptions to this. One exception is a reoccurring dream. Reoccurring dreams are dreams that the person has again and again and the dreams appear to be identical to each other each time they dream them. Reoccurring dreams only occur in the last phase of sleep; they will be the last dreams you have before waking up in the morning. These dreams can last for 45 minutes.
Another exception to this 30 minute limit on dreams are life-like dreams. Like reoccurring dreams, not everyone will have life-like dreams. Also like reoccurring dreams they are the last dreams that you have before waking in the morning. Life-like dreams are dreams that when you waken from them for a few minutes you have trouble distinguishing what is dream and what is real. If the life-like dream was a good one, you are disappointed to find that it was not real. If it was a bad dream, you are relieved to find that it was not real.
Some people dream in color, others in black and white. Color is a phenomenon of the wave length of light that is entering the eye. Since most people sleep with their eyes closed, if color is present in dreams it would have to originate from the brain. Some studies show that creative people tend to dream in color and that analytical people dream in black and white. Most people dream in both color and black and white.
Everyone sleeps and everyone dreams. However, some people remember their dreams and other people do not. Those who don't remember their dreams often believe that they do not dream. Most people approach the waking state following a REM session. They don't wake up, but come near to waking. These people will remember bits and pieces of their dreams. Other people are very sound sleepers and do not approach the waking state following an REM session. These people tend not to remember their dreams. If you know someone who claims not to dream there is a way that you can prove to them that they do dream. Let them sleep while you watch their eyes. When the eyes begin to have rapid eye movements, wake them up and they will have a vivid recollection of what they were dreaming. The same is true for all people. If you waken a person during a dream they recall it clearly and remember the details of the dream.
Psychologists believe that there are three psychological purposes or functions of
dreaming:
1. Mental relief--we have all had the experience of going to bed at night very frustrated or angry with someone or something, only to wake up the next morning and find that we are not as frustrated or as angry as we were the night before. This mental relief comes from dream sleep. Studies show that if a person is deprived of REM sleep, mental relief does not occur. In fact, long term deprivation of REM sleep results in confusion, delusions and hallucinations.
2. Problem solving activity--if we have a problem or are anticipating some important event we often dream about these things. The dreams help us come to terms with new or problematic situations. If a person takes on a new job or goes to a new school, they often dream about being at work or at school. It is believed that dreams help us adjust to such new situations.
3. Wish-fulfilling fantasy--sometimes in dreams we can be things we wish we could be, or be with people we would like to be with.
Biologically, the most important function of dream sleep is brain growth. New born human infants dream four times as much as do adults. Scientists 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. It is known that this brain growth occurs during REM sleep for children and adolescents. It is believed that this may also occur to a lesser extent in adults.
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 serotonin and melatonin are produced by the pineal gland of the brain. Melatonin calms the brain to induce sleep. Serotonin triggers the brain to dream. If the brain is deficient of serotonin, dreaming may not occur.
Alcohol is a drug which causes low levels of serotonin in the brain. Many alcoholics have what appears to be dreamless sleep, which is devoid of REM activity. When alcoholics withdraw from alcohol, many experience delirium tremens (DTs). DTs are characterized by shaking, sweating profusely, anxiety and hallucinations. It is believed that since alcohol depletes the brain of serotonin, when the alcohol is no longer there the brain has a tendency to over produce serotonin for a period of time. This over-production is believed to cause the hallucinations which characterize DTs. Remember that dreams are hallucinations, as the things you see and hear in dreams are really not there.
Surveys indicate that 60% of all dreams are bad dreams, dreams that the person would not want to come true. However, true nightmares are not dreams at all because they do not occur during REM sleep. Instead, they occur just prior to REM sleep. However, the worst type of nightmare does occur during REM sleep and is called a night terror. These are nightmares that occur more often in young people. They wake up screaming and sweating profusely. However, when they are asked to recall what was so frightening about the terror they usually cannot do so. Night terrors can usually be controlled with an antidepressant drug.
Throughout history people have speculated on the meaning of dreams. One of the first comprehensive theories on dream meaning was developed by the Austrian neurologist who developed the psychotherapy known as Psychoanalysis, Sigmund Freud.
Freud divided the human personality into three hypothetical constructs: the id, ego and superego. The id was the only part of the human personality fully functioning at birth. The id recognized human needs and gave these needs mental awareness. However, the id could not take any form of positive action to satisfy these needs. The ego was, according to Freud, the executive part of the personality because it was that part of the personality capable of taking positive action to satisfy needs. Freud felt that, at birth, the child had only the rudiments of an ego in the ability to cry. Crying is positive action to bring someone to satisfy needs for the child. As children grow, they develop many realistic and clever ways to satisfy their needs. This was characterized by Freud as the development of ego strength. The superego was the morality part of the personality. It is a set of rules, values and prohibitions learned in early life, mainly through interaction with parents, caretakers and significant others. The superego contained two parts: the conscience and the ego ideal. The conscience is the part of the superego which punishes us when we violated moral standards. It punishes us by making us feel guilty. The ego ideal pats us on the back, or makes us feel good about ourselves when we live up to our moral standards.
Freud believed that the basic nature of people was hedonistic, a word which means pleasure seeking. He believed that the id wanted to give mental awareness to anything which would bring pleasure. Being hedonistic, the id was a passion pit of wants, lusts and desires which lacked any moral constraint. Freud believed that the superego caused many of our hedonistic passions to become repressed into the unconscious mind. Freud believed that, during sleep, the id and the ego would indulge themselves while the superego was unconscious in sleep. However, if the id became too passionately hedonistic, it would wake the superego. Therefore, Freud believed that the id put dreams in disguised form so as to not arouse the sleeping superego. In psychoanalysis, Freud would attempt to interpret dreams. However, the problem with any form of dream interpretation is that you can never really know if you interpretation is right.
Today it is believed that during REM sleep the brain stem shoots a blast of electrical impulses that, like a shot gun blast, randomly activates the memory of experiences in the cortex. Most of these are recent memories, but old memories are occasionally tapped as well. The brain then takes these random memories and weaves them into a story in an attempt to make sense of these random impulses.
Sleepwalking is known as somnambulism. Young people walk and talk in their sleep more than older people. If a young person walks or talks in their sleep, they will probably out grow this, although sleep talking often does continue through adulthood. Boys walk and talk in their sleep more than girls. Contrary to myth it is not dangerous to awaken a sleepwalker. If you find a person who is sleepwalking, just talk to them and gently escort them back to bed. However, sleepwalkers do occasionally hurt themselves. So if a sleepwalker has walked into a dangerous situation, wake them up. They will be confused and disoriented, but not permanently harmed. However, they may be embarrassed and take a swing at you, so exercise some protective care. Sleepwalking can also be controlled with an antidepressant drug. Sleep talkers are fun to talk to but they usually don't make a lot of sense. When you talk to them, they often become angry that you cannot understand them. Sleep talkers almost never divulge any secrete or important information.
Narcolepsy is a sleeping seizure in which the person suddenly goes into REM sleep. Because REM sleep is accompanied by muscle paralysis, narcoleptics wither to the floor. Narcolepsy is usually triggered by emotional excitement, such as seeing an old friend or hearing a funny joke. Narcolepsy is genetic in origin, and rarely occurs before adulthood. Narcolepsy can't be cured, but is treated with antidepressant drugs and with stimulant drugs called amphetamine.
Bed-wetting is known as enuresis. Bed-wetting occurs more commonly in the young,
and is usually outgrown by adolescence. Bed-wetting also occurs more commonly in
boys than in girls. Although for years bed-wetting was considered a psychological
disorder, it is known today that it is a neurological disorder. In the most
common form of bed-wetting there is an involuntary contraction of the bladder that
occurs about 90 minutes after falling asleep. This occurs because of a
malfunction of the part of the nervous system which controls the bladder. Parents
of bed-wetters can best deal with bed-wetting by:
1. Requesting that the child limit liquid intake during the evening hours.
2. Attempt to void before going to bed.
3. They could wake the child up about 85-88 minutes after falling asleep and escort them to the bathroom.
4. Buy a Wee Alarm--a blanket which electrically activates an alarm when the first drop of urine hits the blanket. The alarm wakes the child and trains them to associate waking up with a full bladder.
5. Buy a rubber or plastic sheet and patiently wait it out.
Parents should never punish or embarrass the bed-wetter. Punishment or embarrassment for bed-wetting can cause psychological problems, as enuresis is usually something that they cannot control.
Sleep apnea is when people stop breathing for long periods of time during sleep.
Sleep apnea occurs most often in older men who are over weight and snore. Because
they do not breath during normal sleep, they must constantly wake up to breath.
Consequently, the first sign of sleep apnea is chronic daytime sleepiness. Sleep
apnea can result in brain damage because the brain is deprived of oxygen. Sleep
apnea can usually be corrected surgically.