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Lecture

PSYCH101 Lecture Notes - Circadian Rhythm, Theta Wave, Delta Wave


Department
Psychology
Course Code
PSYCH101
Professor
Colin Mac Leod

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Sleep & Dreaming
October-14-10
9:09 AM
Not dangerous to wake someone while sleep walking
Consciousness
Sleep is altered consciousness
Our awareness of ourselves and our environment
Closely related to attention
What Watson and the behaviourists wanted to get rid of because they thought it could not be
observed
o When you are typing, what are you conscious of? What you want to say, the keystrokes
Consciousness modulates during the day
Biological Rhythms
Circadian rhythm: the regular biological rhythms that occur on a roughly 24-hour clock; the
'biological clock'
o Alertness, temperature, hormones
o Body temperature rise as morning approaches, peaks during the day, drops when we go to
sleep
o Bright light in the morning activates light sensitive retinal proteins. Proteins trigger signals to
the brain's suprachiasmatic nucleus in the hypothalamus. SCN causes pineal gland to decrease
production of sleep - inducing hormone melatonin
o Artificial light messes with circadian rhythm and delays sleep
Young people's cognition better later in the day, older people's cognition better earlier in the day
Sleep: periodical, natural, reversible loss of consciousness
Sleep Stages
To measure brainwaves, attach electrodes to the head and measure brainwaves.
Awake: beta waves
Five sleep stages every 90 minutes
Just before sleep: alpha waves in the midst of beta waves. Taller, jagged
o Still awake: records alpha waves. Transition to sleep marked by slow breathing and irregular
theta waves.
o Stage 1 sleep: theta waves, more distance between the waves. May experience hallucinations
- sensory experiences that occur without a sensory stimulus
o Stage 2 sleep: sleep spindles, high amplitude, rapid waves. Associated with jerking while
sleeping. K complex: very high amplitude, slow waveform. REM sleep occurs
o Stage 3: delta waves; taller, slower, longer
o Stage 4: deep sleep, relaxed muscles, delta waves account of more than 50%
Rapid eye movement: signals vivid dreaming, also called dream sleep. Spend 25% of time in REM
sleep. Occurs in stage two. Periods increase in length and frequency toward morning. REM rebound
- if we get less than 25% REM sleep we make up for it the next night. Brain's motor cortex active
during REM sleep, but brainstem blocks messages so muscles are completely relaxed
REM rebound: tendency for REM sleep to increase following REM sleep deprivation
Once stage four is reached, you drift backwards to stage two, and back down again
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