Psychology Class Notes > Consciousness & Sleep
Consciousness - the awareness or perception of the environment and of one's own mental processes.
Many books state that consciousness is the awareness of internal and external stimuli.
One problem with this definition, and with this area of study as a whole, is that it seems like an impossible area to understand since we do not know if the experience of consciousness is the same (or even similar) between individuals. I can tell you about my conscious experiences, and you can tell me about yours, but we can never truly understand and appreciate the conscious of others? Can I really understand what it is like to think the way you think or if we imagine things the same way?
I. William James - possibly the most influential figure in the study of consciousness (you know that phrase, "stream of consciousness"? That's his). He identified the following 4 basic perspectives on consciousness. He indicated that, consciousness is:
1) ... Always Changing - can't be held for study: "No state once gone can recur and be identical with what it was before." If that is the case, then how in the world do we study it?
2) ... A Personal Experience - you can try to tell me about your consciousness but I can never appreciate it or experience it.
3) ... Continuous - our awareness is not broken into pieces, and there are no gaps. We really can't tell where one thought ends and one begins. "Consciousness then does not appear to itself chopped up in bits...It is nothing jointed; it flows. A river or stream is most naturally described. In talking of it hereafter, let us call it the stream of thought, of consciousness..."
4) ... Selective - awareness is often a matter of making choices, of selecting what to attend to and what to ignore.
In general, when we speak of "consciousness" we refer to either being awake or being asleep. There are, however, altered states of consciousness:
sleep, drugs, hypnosis, meditation, sensory deprivation, sensory confusion.
BUT - we will focus on sleep from this point on.
A. Measuring Sleep -- Scientists measure sleep with the following:
1) Electroencephalogram (EEG) -- a device that measures the electrical activity of the brain. This is the measure scientists rely on most when determining which stage stage of sleep a person is in. When using the EEG, we look at each wave in terms of the: a) frequency - how many times the wave occurs within a specific period, and b) the amplitude - the size of the wave. These two submeasures help us identify wave types so that, in turn, we can identify different stages of sleep.
2) Electrooculagram (EOG) -- a device that measures eye activity. During different stages of sleep, our eyes move in distinct ways. For example, during slow wave sleep (SWS), we have slow, rolling eye movements, However, during REM sleep, our eye movements are much more rapid and occur in a sharp, back and forth way. The EOG is a vital tool for identifying REM sleep since the EEG in REM, wake and stage look so similar. But, when we combine the EEG and EOG it is easy to see the differences.
3) Electromyogram (EMG) -- this device is used to measure the muscle activity that occurs during sleep, and is particularly helpful when attempting to identify REM sleep. During REM sleep (as you will soon read), humans experience a type of temporary paralysis during which the EMG drops to almost nothing (close to a flat line).
4) Electrocardiogram (ECG or EKG) -- as you most likely know, the electrocardiogram is a measure of heart muscle contractions.
5) Temperature - body temperature is connected with sleep via the sircadian rhythms (your body's internal, biological clock). Although most people believe that the circadian rhythms are a function of time, they in fact work according to body temperature that fluctuates over a 24 (or so) hour period. So, our internal clock seems to function according to our body temperature that varies across a 24 hour period, and not strictly according to time. So, the clock showing 11:00 am does not influence a person's ability to sleep...the body temperature that occurs at that time of day is more important.
B. Types of Sleep (although we use many measures in combination to determine when a person is in which stage of sleep, here we are going to discuss only the EEG, since this is the most prominent feature of sleep. When we use percentages of wave occurrences, we mean that those percentages of brain waves were present in a specific time period of brain wave activity - typically a 50 second period. For example, if we say that the stage is made up of 50% Alpha waves, it means that in a 50 second period, 50% of all the brain waves measurable in that period are Alpha waves):
1) Non-REM Sleep (NREM) -- There are two main categories of sleep, Non-Rapid Eye Movement or Non-REM (NREM) and Rapid Eye Movement (REM). NREM sleep contains all stages of sleep except REM (there are 5, although this is debatable).
a) Stage 0 - also known as wake. In this stage your brain wave activity is composed mainly of alpha and beta wave activity.
Typically, it is said that the more beta waves, the more active and "awake" your brain. However, do not take this to mean that when you sleep your brain is inactive. In fact, your brain is very active in certain stages of sleep, it is just not in a "waking" state. Do you see the difference?
b) Stage 1 - this is the transition stage from wake to sleep. It is that stage in which you are aware that you are about to fall asleep, but haven't just yet.
Approximately 5% of sleep is stage 1, and is characterized by increased amounts of Theta waves and a reduction in Alpha and Beta waves.
This is my favorite type of sleep, since I feel extremely relaxed and comfortable as I am dozing off the sleep. Many people indicate that they are most aware of this when falling asleep, for example, on the couch watching TV. This may be the result of trying to stay awake...the resistance to sleep may prolong stage 1 and make you more aware of it.
c) Stage 2 - This stage of sleep is the most prominent stage as we spend the majority of sleep time in it.
Approximately 45% of sleep time is spent in Stage 2.
Stage 2 is characterized by a mix of Theta, sleep spindles, K-Complexes, & some Delta waves. Look at the image, and you can see all of these different components (although not that well). Let me describe a couple of important ones:
1. Sleep Spindles -- these are short episodes that look (the EEG that is) like small footballs. When looking at the EEG, if you notice an area in which the amplitude (the height of the wave) increases little by little, and the frequency (how close each wave is to the others) decreases slightly, thus giving it the shape of a football, and then goes back to normal, you know you are looking at a spindle.
2. K-Complex -- these are the most sure indicators of stage 2 sleep. When a K-Complex occurs, there is a sudden rise in wave amplitude (height) so the wave goes high above baseline, and sharp decrease in frequency (so the wave looks very wide). Then there is a sudden decrease in amplitude (so the wave now goes well below baseline) and then back to baseline. In addition, there is often a little spike in the wave when it is moving from high above baseline to far below baseline that gives it its characteristic "K" shape. If you are monitoring a persons sleeping EEG, sleep spindles are a nice indicator of Stage 2, but when you see K-Complexes, you know the person is definitely in Stage 2.
d) Stage 3 - This is the first stage of what is considered "deep sleep" or Slow Wave Sleep (SWS).
We spend approximately 7% of our time asleep in this stage, and it is characterized by approximately 20-50% delta waves within minimal amplitude.
Although it is a type of deep sleep, many consider this a transition stage (much like Stage 1) between stages 2 & 4. As a result, there has been a push in recent years to eliminate Stages 3 & 4 and replace them with just a single, "Stage 3" sleep.
e) Stage 4 - This stage is sometimes considered that "true" slow wave sleep stage.
We spend approximately 13% of our sleeping time in Stage 4. The sleeper has definitely entered Stage 4 when there are more than 50% delta waves.
Many people believe that we dream only in REM sleep (in fact, some people refer to REM as the dreaming stage. While it is true we have most of our dreams during REM, we also dream in SWS)
* Note -- NREM sleep is considered inactive sleep, because during these stages, we have decreased Blood Pressure, decreased Heart Rate (measured with ECG), reduced muscle tension (measured with EMG), and slower eye movements (measured with EOG).
2) REM: Occurs in regular intervals every 60-90 minutes.
REM sleep has its own unique pattern of brain waves. The waves look much like the teeth of a saw (means that the waves are fast and close together) and the pattern looks almost identical to stage 1 or wake. How then can we differentiate between REM and Stage 1 or wake?
We rely on the other measures - during REM, muscle activity drops to almost nothing. In fact, did you know that you are virtually paralyzed during REM? It's true. There are many theories about why this is so, but regardless of why we are, the fact is that we are. In addition, eye movements become more frequent and, instead of occurring a slow rolling fashion like in other stages, they are more sharp and occur in a fast, back and forth motion.
REM cycle length seems to be dependent on brain size:
rats = approx every 12 minutes. Also humans have approx twice the amount of REM as other species.
a) dreaming - mostly occurs in REM, approximately 80%, although, as mentioned, we do dream in SWS.
b) age - amount of REM decreases with age.
Pattern of Sleep (Hypnogram): Each human has a unique way and pattern of sleeping, but all follow the same general sleep pattern. When we go to sleep, we...
1) have a rapid descent through the stages, from wake, to Stage 1, Stage 2...all the way to Stage 4
2) then we go back to Stages 3 and then 2 briefly before entering the first REM cycle
3) this first REM period occurs 60-90 min after sleep onset, and is usually very brief (maybe a minute to a few minutes)
4) majority of SWS during first cycle.
5) As the night progresses, we continue to have REM cycles every 60-90 minutes, but length and intensity increases across each cycle. So while the first is very brief and light, the last one of the evening (assuming an 8 hour sleep period) is very long and intense.
6) the second half of night is mainly stage 2 and REM. After the first half of the night we have very, very, little SWS.
** Lots of people say that they do not dream or that on specific nights they did not dream. Well, the reality is we all dream and we all dream every night. However, we remember our dreams when we wake up during one of them. So, if we wake during a REM cycle, we remember or aware of the fact that we were dreaming. This is why people often believe they dreamt in the morning but not earlier in the night - remember that the REM cycle is most intense toward morning (later in the sleep period), so dreaming occurs more frequently and we are more likely to wake during it.
II. Sleep and Age:
1) Infancy - lots of SWS, REM, and total sleep time.
From age 1 to the mid 20s, approximately 25% of peoples total sleep is spent in SWS. In addition, REM decreases from approx 35% to 25% of total sleep time, and total sleep time drops by approximately half.
2) after mid 20s - daily sleep pattern becomes stable from now to approximately age 60, except for SWS which drops dramatically after age 30.
SWS drops from approximately 13% in mid 30s to approximately 5% by age 60.
As you can see, the younger a person is, the more sleep they require. So the next time your parents complain about you sleeping a lot, you can tell them that it has been scientifically documented that younger people require lots of sleep.
III. Sleep Theories
1) Early theories
The early theories focused on what produced sleep not what sleep does (the purpose of sleep). It was originally believed that sleep resulted from a build-up of some substance in the brain that occurred during wake which diminished with sleep. Aristotle actually had similar beliefs 2000 years earlier.
Advances in Physiology resulted in a new perspective that sleep was caused by "congestion in the blood". Some said sleep was caused by blood building up in the brain...some said it was from blood draining from the brain.
2) Behavioral theorists
During the 19th century scientists believed sleep was a result of lack of stimulation...remove stimulation, an organism goes to sleep. Also, it was believed that sleep was an active process of preventing fatigue - "we sleep not because we are intoxicated or exhausted, but to prevent from becoming intoxicated or exhausted."
3) 20th century
The main ideas were substances accumulating in the brain like carbon dioxide, cholesterol, lactic acid, etc. These theories were very poorly formulated and not well supported.
4) The Restorative (restoration) perspective
belief that sleep is used to restore our bodies after wear and tare. Despite the lack of conclusive evidence or supporting data, this is still one of the most popular theories.
Rather than sleep being restorative, this perspective is that sleep is instinctive. Sleep is an "evolutionary leftover". During the days of being hunters, and trying to avoid being the hunted, we needed to be as invisible and quite as possible during the night hours (since we are not nocturnal, we are more easily caught and eaten during those times). As a result, we developed REM sleep so that we can be immobile and silent during the night (remember that we are paralyzed during REM). We are immobile during non-productive hours which can serve to protect us from danger, prevent waste of energy, etc.
III. Sleep Deprivation
One of the best ways to study the importance and function of sleep is to remove it and see what the effects are.
1) longest group studies - these occurred in California during the late 1960s, and included total sleep deprivation for 8-11 days.
2) longest single subject study - Randy Gardner, a 17 year old high school student set out to break the world record for staying awake in order to win a science fair. The previous record was 260 hours of total sleep deprivation (Yikes!).
Once word got out that Randy was trying this, scientists came to monitor and record his progress. Here are some of the things that Randy experienced during that time:
day 1 - nothing unusual, just some fatigue.
day 2 - Randy began having problems focusing his eyes. As a result, he gave up one of the most utilized tools in sleep deprivation studies to remain awake - he stopped watching TV for rest of study.
day 3 - at this point, he started having some minor mood changes, ataxia (poor body movement coordination), speech problems, and nausea.
day 4 - not surprisingly, Randy started getting irritable on day 4, became a bit uncooperative, had some memory losses, poor concentration, and indicated that he felt like tight band around head. he also had a few hallucinations, including mistaking a street sign for a person.
day 5 - Randy started having more hallucinations. For example, Randy insisted he was a great football player (although he clearly wasn't) and became annoyed with any arguments to the contrary. Later in day he began to feel better.
days 6-8 - more ataxia, speech and memory problems.
day 9 - fragmented thoughts and speech, blurred vision, and he became paranoid (he stated that others were out to ruin his attempt to break the record).
After reaching goal, Randy slept for 14.75 hours, after which all of the speech and memory problems disappeared. He also obtained an extra 6.5 hours of sleep over next two nights, regaining 24% of lost sleep including 2/3 of lost stage 4 and 1/2 of lost REM. It is a bit misleading to use the term "regaining lost sleep" as we never truly regain sleep (once gone, it's gone). However, what happens is that we can have an increase in the amount of particular stages of sleep we obtain. This is often referred to as "regaining lost sleep".
Randy's experiences showed us several things about sleep, including:
a) the cerebrum and human behavior are affected, although significantly harmful effects were not found
b) physical condition (BP, Heart Rate, strength, etc) all remained normal throughout the study.
c) circadian rhythms were demonstrated
d) most recovery sleep occurred in one session and most recovery was stage 4 and REM.
IV. Sleep Disorders
1. Insomnia - chronic problem with obtaining a sufficient amount of sleep.
There are 3 basic patterns of insomnia:
a) initial problems falling asleep
b) difficulty remaining asleep
c) persistent early awakenings
Although many people believe they are insomniacs, most are not (pseudoinsomnia). There is a high rate of false belief in insomnia for several reasons. The main reason is that most believe humans "must" get 8 hours of sleep every night. When they go for a period of time without getting 8 hours per night, they assume they have insomnia.
Although many sleep experts (including several that I have worked with) insist that 8 hours is the required minimum for the "normal" adult human to obtain in order to function properly, the research is inconsistent. It is true that cognitive functioning diminishes very quickly when you don't get adequate sleep, but not obtaining 8 hours of sleep does not make you an insomniac. Sorry.
In addition to the myth of 8 hours, there are a couple of other reasons many people believe they have insomnia:
1) people frequently overestimate how long it takes to fall asleep.
2) when a person has had problems falling asleep (even if the problems are only imagined), they often spend time laying in bed worrying about not sleeping. Doing this produces anxiety, which in turn, reduces the likelihood that you will fall asleep.
As you can see, Insomnia is not a physical problem but a psychological one. So, how do we correct it? the Solution: Sleep Hygiene:
a) don't take naps during the day
b) try to wake up at the same time each day - helps circadians
c) only attempt to sleep when sleepy
d) associate bed with sleep
2) Narcolepsy - sudden and irresistible onset of sleep during waking hours.
characteristics of narcolepsy:
a) person goes directly from wake to REM. Studies have indicated that excitement tends to produce a narcoleptic fit.
b) obviously, this is a very dangerous disorder
c) etiology (cause) is unknown - true narcolepsy is rare
3) Sleep Apnea - reflexive gasping for air which awakens person and disrupts sleep. During different stages of sleep, the Apneac's muscles become so limp that the air passages essentially close. This has serious ramifications as it make it difficult for the sleeper to get enough oxygen.
a) although the Apneac may be unaware of it, they may have hundreds of awakenings a night
b) blood oxygen level can go as low as 30% (I can't express to you just how dangerous this is. Just take my word for it, 30% oxygenation is very dangerous)
c) muscles become completely limp (has been linked to SIDS - sudden infant death syndrome)
4) Night Terrors - abrupt awakenings from NREM sleep accompanied by intense autonomic arousal and feelings of panic.
a) usually occurs during SWS
b) this is most common in children ages 3-8, although it sometimes occurs in adults
c) typically during a night terror, the child will sit upright, scream a lot (one father told me that it sounds like the child is being murdered), but then just stops and goes back to sleep.
d) Usually the child has no recollection of the event
e) not indicative of emotional disorders
5) Somnambulism (sleep walking)
a) despite what your mother may have told you, a sleep walker is Not acting out a dream
b) typically, sleep walking occurs during SWS
c) etiology is unknown - may be affected by stress
d) often accident prone
Despite an incredible amount of interest, empirical study of dreams is relatively new and unsophisticated.
Generally, research consists of waking people up during REM and asking them about content of their dreams, OR the subjects are asked to keep a log of dreams over a period of time. Do you see any problems with this??
Validity is very questionable - anytime you are asked to "remember" something, there are gaps in your memory which you attempt to fill in. Therefore, memory is subjective and often flawed when asked to remember things that occurred while you were awake. Imagine how much greater the problems are when you are asked to remember something that occurred when you were asleep.
A. Dream Content:
most dreams are mundane - consist of familiar settings, with known characteristics like friends and family. Take a look at this short list of common themes (adapted from Wieten, 1992)
|type of dream||frequency reported (%)|
|being attacked or pursued||77|
|trying repeatedly to do something||71|
|school, studying, teachers||71|
Not as exciting as you may have thought!
Dreams seem to be influenced by our waking lives (stress, happiness, trauma, etc influence dream content). This makes a lot of sense. When we sleep, we are the same people we were while awake, with the same problems, concerns, things that make us happy, excited, etc. Why should our thought process be so drastically different when we sleep? Should we become different people when we sleep?
B) Dream Theories:
1) Freud - believed dreams were a way to achieve wish fulfillment (what you lack in your life you get in your dreams). He stated that there are 2 types of content in all dreams:
a) Manifest dream content - what you remember about the dream
b) Latent dream content - what the dream was actually about
Freud believed that to understand dreams, you need to understand both Manifest and Latent content, as well as:
a) Displacement - emotional feelings are displaced from one object to another.
For Example - you dislike Greg who you see everyday in school. You just want to burst when you see him, but never say anything to him.When you sleep, you have a dream that you beat up his younger brother, Bobby. Thus, your hatred for Greg is expressed as dislike for and aggression toward poor Bobby.
b) Symbolization - latent content is converted into manifest symbols. Many meanings are disguised in dreams, and appear not as themselves, but as figures.
For example, you have a dream you are riding on a "train" that is traveling "out of control" and suddenly goes "through a tunnel"...do I need to go on with this example?
2) Rosalind Cartwright (Cognitive Problem Solving View) - dreams are a way to work out every day problems. We have no social, moral, or ethical constraints during sleep that we have during wake, so we can take care of business in ways we can't when awake.
3) Activation Synthesis Model (Hobson & McCarley) - dreams are byproducts of bursts of neural activity in the subcortical area of the brain. Brain is getting neural impulses that are not important or useful so it simply tries to make sense of them.
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