Levels of Awareness
• No Awareness – unconscious
• Subconscious Awareness – things you do without thinking, such as walking up stairs
• Primary Awareness – normal level of awareness
• Self-Awareness – metacognition, thinking about what and how you are thinking
• Altered States of Awareness – changing (un)conscious activity in an artificial fashion
Sleep and Waking
• The sleep-wake cycle
– Infants sleep 2/3 of day, senior sleep ¼ of day
• Why do we sleep?
– Accumulated wastes, depleted reserves
– Bottom line – we don’t know !!!
– *People need a minimum of 6 solid hours of sleep per night. (brain dumps out irrelevant information
from the day and stores memories/emotions). More like 7-8 hours when brain is more busy, such as
when studying for exams.
• Circadian Rhythms
– Day and night people
– Controlled by hypothalamus; pineal gland
• Sleep Deprivation
– Reduces function of the immune system, supresses it
– Time required to fall asleep drops significantly after only one sleepless night
• Circadian rhythms regulated by suprachiasmatic nuclei (SCN)
• SCN neurons link to pineal gland, which secretes melatonin
• Consciousness includes awareness of
• a. external events only
• b. internal sensations only
• c. self only
• d. external events, internal sensations, and self
• An electroencephalograph is a device that measures
• a. glucose metabolism in the brain
• b. electrical activity of the brain
• True or False
• In general, research into circadian rhythms has found that overall level of alertness and
body temperature are negatively correlated. TRUE
9 What happens when we sleep?
• Sleep – differentiated into stages
• –Differences in muscle tension, eye movements
1 – Stage 1: light sleep, EEG shows synchrony (neurons start firing more together)
– Stage 2: K-complexes, sleep spindles (which are when neurons are falling out of synchrony)
– Stage 3: increased sleep spindles, Delta waves (more synchrony)
– Stage 4: Delta waves predominate, night terrors (clusters of neurons firing at the exact same time) –
night terrors, bed wetting, sleep walking, etc.
• Progression through stages (1,2,3,4,3,2,REM) takes about 60 min
REM (happens just before return to stage 1)
• EEG – alpha waves – should be awake
• Decrease in muscle activity
• Increase in cortical blood flow
• Dreams (not all dreams, but most, occur in REM sleep)
• Length of REM sleep 10-60min
• What do we know about REM sleep
– REM rebound (catching up on REM sleep from previous nights with less sleep)
– REM sleep shuts down muscle activity (basically paralyzed).
13 Sleep to Wakefulness
• RAS responsible for wakefulness
– Inhibition by thalamus, hypothalamus – sleep
• Role of hypothalamus
– Damage produces permanent wakefulness
– Mechanisms related to regulation of body temp.
• Lower Brainstem
– Raphe nucleus
– Locus coeruleus – shuts down muscle activity
•Responsible for dream related phenomenon (acting out their dreams)
– Preoptic area – increased brain wave synchrony
• Sleepwalking – NOT during REM sleep
14 Activity of neurons in the locus coeruleus
during wakefulness and stages of sleep
15 Sleep Summary
• During 24 hr. cycle
– Areas in brainstem and hypothalamus become active
– Inhibit RAS impulses to cortex
– REM sleep – impulses to motor cortex blocked
– Sleep ends when these areas decrease activity
– Circadian Rhythms – still a mystery?
• Why do we need to spend a 1/3 of our life unconscious?