Consciousness and Cognition
What Does It Mean To Be Conscious, And Are There Different Levels Of
Consciousness?
Definition of Consciousness
Consciousness is a person’s awareness of everything that is going on at any
given moment. Most waking hours are spent in waking consciousness.
Altered States of Consciousness
Altered states of consciousness are shifts in the quality or pattern of mental
activity.
Why Do People Need Sleep, And How Does It Work?
Sleep is a circadian rhythm, lasting 24 hours.
Most adults require seven to nine hours of sleep per 24-hour period.
What Are The Different Stages Of Sleep, Including The Stage Of Dreaming And Its
Importance?
The Stages of Sleep
Non-REM stage 1 is light sleep.
Non-Rem stage 2 sleep is indicated by the presence of sleep spindles— bursts
of activity on the EEG.
Non-REM stage 3 is highlighted by the first appearance of delta waves, the
slowest and largest waves.
Once delta waves account for more than 50% of total brain activity, the person is
in Stage 4 sleep and the body is at its lowest level of functioning. Eventually delta
waves become the predominant brain activity.
, What happens in REM sleep?
After spending time in stage 4, the person will go back up through stage 3 and 2,
and then enter a stage in which body temperature increases, the heart beats
faster, the eyes move rapidly under the eyelids, and brain waves resemble beta
waves— REM sleep.
90% of dreams occur in REM sleep.
REM sleep occurs four or five times a night, replacing stage 1 in the sleep-wake
cycle, and is accompanied by paralysis of the voluntary muscles.
REM behaviour disorder is a rare condition in which REM paralysis fails and the
person moves violently while dreaming, often acting out the elements of the
dream.
The need for REM sleep
REM sleep serves a different purpose than NREM (non-REM) sleep.
After a physically demanding day— NREM sleep.
After an emotionally stressful day—REM sleep—suggests that REM sleep is a
way of dealing with anxiety.
Early studies of REM sleep seemed to show that a lack of REM sleep would lead
to madness, but later research has consistently shown this to be untrue.
REM sleep in early infancy differs from adult REM sleep.
Infants do not dream but rather form new connections between neurons.
If deprived of REM sleep, the following night the person will experience greatly
increased amounts of REM sleep, known as REM rebound.
How do sleep disorders interfere with normal sleep?
Sleep disorders
Nightmares are bad or unpleasant dreams that occur during REM sleep.
Sleepwalking, or somnambulism, is more common in childhood and seems to be
at least partially hereditary.
What Does It Mean To Be Conscious, And Are There Different Levels Of
Consciousness?
Definition of Consciousness
Consciousness is a person’s awareness of everything that is going on at any
given moment. Most waking hours are spent in waking consciousness.
Altered States of Consciousness
Altered states of consciousness are shifts in the quality or pattern of mental
activity.
Why Do People Need Sleep, And How Does It Work?
Sleep is a circadian rhythm, lasting 24 hours.
Most adults require seven to nine hours of sleep per 24-hour period.
What Are The Different Stages Of Sleep, Including The Stage Of Dreaming And Its
Importance?
The Stages of Sleep
Non-REM stage 1 is light sleep.
Non-Rem stage 2 sleep is indicated by the presence of sleep spindles— bursts
of activity on the EEG.
Non-REM stage 3 is highlighted by the first appearance of delta waves, the
slowest and largest waves.
Once delta waves account for more than 50% of total brain activity, the person is
in Stage 4 sleep and the body is at its lowest level of functioning. Eventually delta
waves become the predominant brain activity.
, What happens in REM sleep?
After spending time in stage 4, the person will go back up through stage 3 and 2,
and then enter a stage in which body temperature increases, the heart beats
faster, the eyes move rapidly under the eyelids, and brain waves resemble beta
waves— REM sleep.
90% of dreams occur in REM sleep.
REM sleep occurs four or five times a night, replacing stage 1 in the sleep-wake
cycle, and is accompanied by paralysis of the voluntary muscles.
REM behaviour disorder is a rare condition in which REM paralysis fails and the
person moves violently while dreaming, often acting out the elements of the
dream.
The need for REM sleep
REM sleep serves a different purpose than NREM (non-REM) sleep.
After a physically demanding day— NREM sleep.
After an emotionally stressful day—REM sleep—suggests that REM sleep is a
way of dealing with anxiety.
Early studies of REM sleep seemed to show that a lack of REM sleep would lead
to madness, but later research has consistently shown this to be untrue.
REM sleep in early infancy differs from adult REM sleep.
Infants do not dream but rather form new connections between neurons.
If deprived of REM sleep, the following night the person will experience greatly
increased amounts of REM sleep, known as REM rebound.
How do sleep disorders interfere with normal sleep?
Sleep disorders
Nightmares are bad or unpleasant dreams that occur during REM sleep.
Sleepwalking, or somnambulism, is more common in childhood and seems to be
at least partially hereditary.
