The Body During Sleep
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- The body during non-REM sleep. We have a uniform heart rate and breathing. The eyes move slowly, in contrast to the rapid eye movements of REM. The body is not experiencing "sleep paralysis," but neither is it receiving instructions for movement.
- The body during dreams. It experiences an increase in heart rate, blood pressure, gastric acid (in people who have ulcers), body temperature, metabolic rate, blood flow in the brain, and glucose consumption. Certain hormones are released, but others are suppressed. The heart also becomes more vigorous; this might be one reason for the heart attacks which some people experience during sleep. Our respiration rate varies according to the content of the dream; if we dream that we are running, we breathe rapidly. (During lucid dreams, our heart rate and oxygen consumption are even higher than they are during non-lucids.) Our large muscles become very relaxed and, in a sense, paralyzed (thus, "sleep paralysis") -- probably so that those muscles cannot "act out" any dreams which occur; however, muscles might twitch in the face and fingers. The sexual organs are stimulated (particularly if the dream has sexual content, or if the dreamer during wakefulness has been sexually aroused or deprived); a man experiences an erection (partial or full), and a woman's vagina becomes moist. The body is more physiologically active during later REM periods than it is during the first period.
- The eye movements. During a study of sleep-time EEG readings in the 1950s, Eugene Aserinksy and Dr. Nathaniel Kleitman "discovered" rapid-eye movements in infants; their first series of subsequent experiments were based on the assumption that REM occurred only in infants, and only later did they find that adults also exhibit REM. The rapid-eye movements during REM occur probably because we look at moving objects in our dreams. In lucid-dream experiments, when people moved the eyes of their dream-body in a left-right pattern, their physical eyes moved accordingly. Eye movements are measured in a sleep lab by an electrooculogram (EOG).
- What is sleep paralysis? It is a natural condition which occurs when we are in REM sleep; we might become aware of it when we are falling asleep into REM or waking up from REM. In this state, we are unable to move or speak. This is called "the cataleptic state" in Oliver Fox's book, Astral Projection.
- Why does sleep paralysis happen? During REM sleep, a dream seems real because the brain is issuing commands to the muscles to enact the action which is depicted in the dream; from the perspective of those parts of the brain, the dream scenario is happening physically. Obviously we would be endangered if we walked and ran in our sleep (with eyes closed and no sensory input from the physical world). To protect us, the brain paralyzes most muscles so that they cannot respond to the commands; this condition is described medically as a "profound loss of muscle tone." The paralysis is accomplished by "neural inhibitors" in the bloodstream; in experiments where these inhibitors were blocked in cats (chemically or by surgically removing the parts of the brain which inhibit motor activity during dreams), the animals dramatized their REM sleep with vigorous movement. We might experience sleep paralysis consciously when we wakefully enter the REM state -- or when we awaken directly from REM (and, for some reason, the endocrine system continues to release the neural inhibitors which sustain the paralysis).
- Sleep paralysis is not total. The exempt muscles include those of the lungs and heart -- and the eyes, as in "rapid eye movement." The heart and lungs are obviously needed for the maintenance of life, but we can only wonder why the eyes are also excluded. Other parts of the body are able to exhibit some movement. Paralysis is most thorough in the large muscles (and the voice muscles) which would dramatize our dream (but we have all seen dogs twitching their legs during apparent dreams). In laboratory tests, dreamers were awakened to describe their dream actions; the muscles which would correspond to those actions had been registering slight movements and increases in muscle tension and electrical activity. During tests on lucid dreamers, the paralysis was more acute, but the sleeping subjects were able to consciously create physical-body twitches in their hands, forearms, and feet (with an intensity corresponding to the dream-body's experience). The lucid dreamers could also control their breathing -- "holding" it or breathing rapidly.
- Some people don't experience sleep paralysis. This rare condition, REM Sleep Behavior Disorder, prevents sleep paralysis, so the victims act out their dreams with some or all of their muscle facility. Imagine the danger and destruction which would occur if we portrayed some of our dreams and nightmares; one man who has this condition dreamed that he was attacked by a wild animal, and when he tried to break its neck, he was awakened by the screams of his wife whom he had supposed to be the beast.
- Sleep paralysis is harmless but it might be frightening. When I first experienced sleep paralysis, I had never heard of it; I awoke but could not move, and I was overwhelmed by terror and confusion. Now I know that sleep paralysis is a normal component of REM sleep; in that instance, I went back to sleep, but the immobilization would have dissipated soon after this awakening anyway. When sleep paralysis occurs, all that we can do is wait for the condition to wear off, while gently trying to move our facial muscles and other muscles. However, sleep paralysis might be fatal to infants; some researchers have speculated that SIDS (Sudden Infant Death Syndrome) occurs when the neural inhibitors are released in excessive amounts, paralyzing not only the muscles which need to be constrained but also the heart and lungs.
- Certain effects might accompany wakeful sleep paralysis. During my first incident of sleep paralysis, another phenomenon added to the horror: I saw the image of a sinister-looking "spirit" sitting next to me, and I concluded that it must be causing the paralysis as part of an "attack." (I apparently misunderstood the paralysis, but I believe that the spirit presence was real.) By the time I had my second experience of sleep paralysis, I had read about it, but I was too groggy to identify my condition as such; I distinctly heard the sounds of two or three people walking around in my bedroom, and then I felt them running their hands across my body -- and I wanted to jump up and defend myself, but I was could not move, and I thought that the paralysis was due to terror. During sleep paralysis, many people say that they are assaulted by images which resemble people, monsters, succubi and incubi (which are explained in the chapter on nightmares), or a general fiendish presence. They might also experience hallucinations, sounds (buzzing, hissing, roaring), and bodily sensations (vibrations, electricity, a sense of being touched, difficulty in breathing, or a weight on the chest). Some people feel that they are leaving their body; this and the other symptoms do parallel those of the out-of-body (OBE) state.
- The characteristics of sleepwalking. Sleepwalkers have certain attributes in common.
- The families. Sleepwalking is a typical, normal activity of young children; most people outgrow it (but the behavior is often passed to their children).
- Abilities. Sleepwalking children tend to move awkwardly and can perform only simple tasks. Adults have achieved complex actions, such as driving a car.
- Behaviors. Sleepwalkers often engage in repetitive movements; e.g., opening and closing a door incessantly. They might pursue a forbidden venture, such as eating food which is not permitted by their diet.
- The wakeful precursors. Sleepwalking is most likely to occur when the wakeful activities have precipitated an unusually deep "stage 4" during the first cycle of the sleep period. That condition might have been caused by exhaustion (from strenuous wakefulness or from previous lack of sleep).
- The length of time. Sleepwalking usually ends within 15 minutes.
- The motivation. Sleepwalkers are generally prompted by fear or concern; they get out of bed to resolve an imagined problem. They are not responding to a REM dream.