PSYA01H3 Chapter Notes - Chapter 9.7: Slow-Wave Sleep, Sleep Spindle, Medium Frequency
SLEEP
Sleep not state of unconsciousness but an altered state of consciousness
People sleep a third of their lives, but why do we need sleep
The Stages of Sleep
Polygraph: instrument that records changes n physiological processes such as brain activity,
heart rate, and breathing
Can record info through small metal disc pasted to scalp producing EEG
Electroencephalogram (EEG): measurement and graphical presentation of electrical activity of
muscles, recorded by electrodes attached to skin
Can record electrical signals from muscles producing EMG, heart producing EKG, or eye
movements through metal discs attached to skin around eyes EOG
Electromyogram (EMG): measurement and graphical presentation of electrical activity of
muscles, recorded by electrodes attached to skin above them
Electrocardiocram(ECG): measurement and graphical representation of the electrical activity of
heart, recorded by electrodes attached to the skin
Electro-oculogram(EOG): measurement and graphical representation of the electrical activity
caused by movements of the eye recorded by electrodes attach to skin adjacent to eye
EEG record distinguishes between alert and relaxed states of wakefulness. When alert tracing is
irregular and doesn’t move far up or down.
Beta activity: irregular, high-frequency activity of the EEG usually indicating state of alertness
or arousal
When relaxed or drowsy: alpha activity: rhythmical, medium frequency activity of EEG usually
indicating state of quiet relaxation
First stage of sleep marked by theta activity
Theta activity: EEG activity of 3.5-7.5 Hz occurs during transition between sleep and
wakefulness
EMG shows muscles active, EOG show slow rolling eye movements
EEG slowly gets lower in frequency and higher in amplitude – interrupted 2-5 times a night by
sleep spindles (short bursts of 12-14hz waves)
As sleep progresses gets deeper through stage 2, 3, and 4
Stage 4 consists mostly of delta activity: rhythmical activity of EEG having frequency less than
3.5 indicating deep slow wave sleep
Slow-wave sleep: sleep other than REM sleep, characterized by regular slow waves on ECG
Stage 4 reached in less than hour and continues for long as half hour.
THEN suddenly ECG raises and sleeper raises stages back from 3, 2, 1 and heartbeat becomes
irregular and respiration alternates between shallow breaths and sudden gasps
EOG shows eyes dart rapidly back and forth, up and down, chart looks as if awake but actually
fast asleep. EMG generally quiet but hands and feet twitch occasionally
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Document Summary
Sleep not state of unconsciousness but an altered state of consciousness. People sleep a third of their lives, but why do we need sleep. Polygraph: instrument that records changes n physiological processes such as brain activity, heart rate, and breathing. Can record info through small metal disc pasted to scalp producing eeg. Electroencephalogram (eeg): measurement and graphical presentation of electrical activity of muscles, recorded by electrodes attached to skin. Can record electrical signals from muscles producing emg, heart producing ekg, or eye movements through metal discs attached to skin around eyes eog. Electromyogram (emg): measurement and graphical presentation of electrical activity of muscles, recorded by electrodes attached to skin above them. Electrocardiocram(ecg): measurement and graphical representation of the electrical activity of heart, recorded by electrodes attached to the skin. Electro-oculogram(eog): measurement and graphical representation of the electrical activity caused by movements of the eye recorded by electrodes attach to skin adjacent to eye.
