Figure 1-4i. Sleep inducing sites in thebrain.Figure 2-4i. Diagram of recording EEGs on a paper tape.asgn4i -- ALTERED STATES OF CONSCIOUSNESS: SleepThis exercise summarizes the basic brain processes in sleep and the use of the EEG(electroencephalogram; "brain waves") to measure sleep stages. It includes the following topics:! sleep as an active process and brain areas that turn it on ! the EEG: how it is recorded and what it shows about brain activity! the EEG for the two basic kinds of sleep, slow wave sleep (SWS) and rapid eye movement sleep(REM) and their associated physiological and psychological processes! the division of SWS into four stages! the alternation between SWS and REM sleep during a night's sleep! developmental changes in sleepSleep: An Altered State of ConsicousnessWhen people think of altered states of conscious-ness, they often think ofstates induced by drugs, by hypnosis, or some other exotic (~unusual)process. However, each of us experiences an altered state ofconsciousness (almost) every day -- or rather, night. It's called sleep. Itcertainly qualifies as an altered state of consciousness.! Sleep is an active process generated by a specific brain system. Sleepis not just the absence of waking. It is a process that actively shuts downthe brain. Most people know this from personal experience. When youhaven't had enough sleep, you can doze off almost anywhere, as long assomething or someone is not directly trying to keep you awake.Several brain areas are involved in producing sleep. Two important onesare small areas in the caudal (back end of) brain stem (Vertes, 1984) andin the lower, front part of the limbic system (Sterman & Clemente, 1974). Figure 1-4i shows the locations of these structures. Damage in theselocations abolishes the capacity to fall asleep, whereas electrical orchemi-cal stimulation at these sites makes animals curl up and fallasleep, just as they do normally.Q1. After "pulling an all-nighter," Joe dozes off at dinner with his girlfriend. What process makes him doze off? [Hint: A name is not an explanation. What process directly produces the dozing?]A. he's sleepy after the "all-nighter" B. his girlfriend is boring and the food tastes blahC. the brain slows down as a person goes to sleepD. specific places in his lower brain stem and limbic system are activeE. dreams are active, so they shut the brain down to let them happen F. A, B, C, D, & E are all correct! The EEG and other signals of body activity arerecorded with a polygraph (poly = many; graph =writing). Hans Berger’s discovery of theelectroencephalogram (EEG, or "brain waves") in1929 opened the way for major developments in sleepresearch. Figure 2-4i shows how EEGs and other bodyprocesses were recorded with a polygraph.The upper part shows electrodes stuck on the scalp to pick upthe tiny electrical signals from the brain that can be detectedfrom the scalp. Two dozen or more electrodes are used at atime. Other electrodes stuck on the skin measure eyemovements, muscle activity, especially from the neck or jaw,and other body reactions. The electrical signals the electrodespick up go to amplifiers in the polygraph.asgn4i p. 2Figure 3-4i. The EEG about 45 minutes after fallingasleep at night.Figure 4-4i. Changes in the EEG over the first 90minutes of sleep.The lower part of Figure 2-4i shows the way a traditional polygraph records the electrical signals from the skin. Theamplifiers strengthen the signals so they can drive pens to move up and down. The bigger the electrical changes picked upfrom the scalp, the bigger the up-and-down pen movements are. The pens write on a long paper tape pulled under them at aconstant rate. This draws a very long graph, with time on the long horizontal axis and with electrical signals of the EEG,eye movements, muscle tension, etc. on the vertical axis. Modern systems save the signals in digitized form for computeranalysis.[The following EEG records were extracted from A Manual of Standardized Terminology, Techniques, andScoring System for Sleep Stages in Human Subjects. A. Rechtschaffen & A. Kales, Eds. National Institute ofNeurological Diseases and Blindness, Dept. of Health, Education, & Welfare, Bethesda, MD 1968.]Figure 3-4i shows the polygraph record of activityrecorded for about 20 seconds of sleep about 45minutes after falling asleep. The top two traces showeye movements, the third shows neck muscle tension,and the bottom three record EEG from three differentlocations on the scalp over different lobes of thecerebral hemisphere. The vertical axis shows changesin the electrical signals. The horizontal axis is time.! The EEG shows systematic changes over a night'ssleep. An early finding was that the EEG changeswhen a person falls asleep. As a person (or animal)falls asleep, the EEG goes through a series of stages. During waking the EEG shows low amplitude (small),high frequency (many waves per second) activitycalled beta waves. As a person falls asleep, the EEGchanges, showing progressively bigger and slowerwaves (longer lasting waves; few waves per second). This pattern of EEG activity gives this stage of sleepits common name: Slow Wave Sleep (SWS) Figure4-4i illustrates these changes.! The brain, the mind, and the body become more andmore inactive in progressively deeper stages of slowwave sleep. As you fall more deeply into SWS, the"brain waves" become slower and bigger, which is asign of decreased brain activity. We know this fromexperiments on animals, which show that mostneurons in the brain are relatively inactive. Associatedwith the increasing amount of slow wave activity is adecreasing amount of mental activity and level ofconscious awareness.Q2. You can tell when a person falls asleep from the EEG because itA. stops showing any brain wave’s B. shows that the brain cells are much less activeC. shows more and more low frequency (slow), high amplitude (big) activityD. shows more and more beta waves E. B, C, & D are all correctThe first change in the EEG appears as you relax,close your eyes, and empty your mind. The EEG nowshows bursts of activity at 8 - 12 Hz, called alphawaves, and beta activity declines. As you begin to fallasleep, the alpha activity breaks up and the EEGshow rather small, irregular waves, with some betaactivity riding on slower brain waves. This is stage 1of slow wave SWS. The subsequent stages showincreasing amounts of slow wave activity. Stage 4 isthe deepest stage of slow wave sleep. At this