PSYC 1010 Chapter Notes - Chapter 5: Sleep Spindle, Delta Wave, Mind-Wandering

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23 Feb 2011

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Readings- Chapter 5
The Nature of Consciousness
Consciousness: the awareness of internal & external stimuli
We have some degree of awareness when were asleep
It is continuously changing stream of consciousness
Variations in Awareness & Control
Some of our consciousness is intentional
Mind wandering: peoples experience of task-unrelated thoughts, thoughts that arent related
to what theyre intentionally trying to do at a given moment
People spend 15%-50% of their time mind wandering
Controlled processes: judgments or thoughts that we exert some control over, that we intend
to occur
Automatic processes: happen without our intentional control or effort
Consciousness & Brain Activity
Consciousness doesnt arise from any distinct structure in the brain, but from activity in
distributed networks of neural pathways
Electroencephalograph (EEG): a device that monitors the electrical activity of the brain over
time by means of recording electrodes attached to the surface of the scalp
The EEG summarizes the rhythm of cortical activity in the brain in terms of line tracings
called brain waves
Human brain waves are divided into 4 principal bands, based on the frequency of the waves
Different patterns are associated with different states of consciousness (SEE NOTEBOOK)
Biological Rhythms & Sleep
Past 3 decades have demonstrated the critical impact that has on many of the important
processes & tasks that we engage in every day
Biological rhythm: periodic fluctuations in physiological functioning
The Role of Circadian Rhythms
Circadian rhythms: the 24-hour biological cycles found in humans & other species
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They are influential I the regulation of sleep
Ie, body temperature varies rhythmically in a daily cycle
People fall asleep as their body temperature begins to drop & awaken as it begins to ascend
Everyone has an ideal time when they are most likely to fall asleep
Sleep quality may be more strongly correlated with health & well-being than with the sheer
quantity of sleep
Daily exposure to light readjusts peoples biological clocks
Ignoring Circadian Rhythms
What happens when you sleep at an unusual time?
The quality of your sleep suffers
If you get less sleep than you need, you accumulate sleep debt can be paid back by getting
extra sleep
Readjustment process takes about a day for each time zone crossed
Speed of readjustment depends on the direction travelled
Readjustment is easier when flying west & lengthen your day than when you fly east &
shorten your day
studies have found that teams flying west perform significantly better than teams flying east
Melatonin & Circadian Rhythms
melatonin (hormone) can reduce the effects of jet lag but research is inconsistent, due to the
timing of the dose & light settings
The Sleep & Waking Cycle
sleep labs are created for researchers to study them while they sleep
electromyography (EMG) records muscular activity & tension
electrooculograph (EOG) records eye movements
other instruments are used to monitor heart rate, breathing, pulse rate & body temperature
Cycling Through the Stages of Sleep
5 main stages while sleeping
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Stages 1-4
Length of time it takes for people to fall asleep varies depending on how long its been since
they last slept, where the person is in their circadian cycle, the amount of noise/light in the
sleep environment, the persons age, desire to fall asleep, boredom level, recent caffeine or
drug intake, stress level etc
Stage 1 is a brief transitional stage of light sleep that usually lasts only a few (1-7 mins)
Breathing & heart rate slow as muscle tension & body temperature decline
Hypnic jerks: brief muscle contractions that occur as people fall asleep
Stages 2, 3, & 4, respiration rate, heart rate, muscle tension & body temperature continue to
Stage 2 (lasts 10-25 mins), brief bursts of higher-frequency brain waves, called sleep spindles
appear against a background of mixed EEG activity
Brain waves become higher & slower in frequency as the body goes into slow-wave sleep:
consists of sleep stages 3 & 4, during which high-amplitude, low-frequency delta waves
become prominent in EEG recordings
People reach this stage after about 30 mins, & stay there for 30 mins
REM Sleep
People fall back into light sleep (stage 1) & go directly to stage 5 REM sleep
Researchers use an electrooculograph to monitor side-to-side movements that occur beneath
the sleeping persons closed eyelids
REM sleep was discovered by accident in the 1950s
This is a very deep stage of sleep, its hard to wake someone up from it
There is irregular breathing & pulse rate
Muscles are completely relaxed; little to no movement
Most dream reports come from the REM stage
Repeating the Cycle
During the course of the night, people tend to repeat the cycle about 4 times
The first REM period is short, only lasting a few mins
REM periods get longer, peaking at around 40-60 mins
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