Sleep and Dreams
UNIT 5- RG 5A
Rhythm of Sleep
Circadian Rhythms occur on a 24-hour cycle and include sleep
and wakefulness
Controlled by the hypothalamus,
specifically the suprachiasmatic
nucleus (SCN)
● receives input from the eyes & is
especially sensitive to the light
dark cycles of day and night
● light signals the SCN to tell the
pineal gland to stop release of
melatonin…in darkness SCN no
longer sends messages,
increasing melatonin
Under normal circumstances, the pattern undergoes
levels and sleepiness
Illustration © Cynthia Turner
2003
daily readjustment by our exposure to light and by our
habitual routines
The Basic Sleep Cycle
The first 90-minutes of sleep
We experience 4-6 sleep cycles on an average
night.
Sleep Stages 1-4 --“Quiet Sleep”
Light sleep
Stage 1 – just drifting to sleep, may experience fantastic
images and/or auditory hallucinations
Stage 2 – more relaxed, clearly asleep – sleep spindles
(short bursts of brain activity) occur
Deep sleep (brain activity significantly slowed)
Stage 3 – transitional stage to deeper sleep
Stage 4 – deepest sleep of all, hard to awaken…only
occurs during the first few cycles of the night
REM Sleep – Paradoxical Sleep
After reaching the deepest sleep stage (4) the sleep cycle
starts moving backward towards stage 1. Although still
asleep, the brain engages in low amplitude, fast and
regular beta waves, much like awake-aroused state.
A person in this sleep phase exhibit Rapid Eye Movements (REM)
and reports vivid dreams.
Brain very active, yet major muscles in body relaxed/paralyzed.
How much sleep do we need?
We spend one third of
our life sleeping.
Genetics influence exactly
how much sleep we
need…however most
humans sleep 9-10 hours if
left unhindered.
Adults need a bit less sleep
than teenagers & children
do.
How much sleep do we need?
Our brain keeps track of
the amount of sleep we
get and does not let us
“make up” for lost sleep.
Once it’s gone, it’s gone.
You do, however, tend to
get more stage 4 and
REM.
Sleep Deprivation
Sleep deprivation studies have shown us that sleep is a
necessary biological function. If we don’t get enough
sleep, we can experience…
1.difficulty focusing
2.diminished productivity
3.greater tendency to make mistakes
4.irritability and fatigue
5.diminished immune system
6.hallucinations (usually after 72
hours)
Sleep Deprivation
The National Sleep Foundation found that over ½ of all
American’s are getting less sleep than they need!
Sleep Theories
1.Sleep Protects: Sleeping in the darkness when
predators loom kept our ancestors out of harms way.
2.Sleep Recuperates: Sleep helps restore and repair
brain (and body) tissue.
3.Sleep Helps Remembering: Sleep restores and
rebuilds our fading memories.
4.Sleep and Growth: During sleep pituitary gland
releases growth hormone. Older people release less
of this hormone and sleep less.
Sleep Disorders
1.Insomnia: difficulty falling asleep or
staying asleep
2.Narcolepsy: overpowering urge to fall
asleep that may occur while talking or
standing up
 Experience sleep attacks that usually last 5 minutes or
less…this can mean lapsing directly into REM sleep for
some people
Sleep Disorders
1.Night terrors: Sudden arousal from sleep and intense fear
accompanied by physiological reactions (occurs usually during
1st cycle)
 Seems to be related to some fear the child has…but is not
the same as a nightmare (bad dream)…just see images
 If not awakened, child often not remember in the morning
2.Sleep apnea: Failure to breathe when asleep
 Wake up (100s) of times a night so
begin breathing again
 Treatments include weight loss
and CPAP machine
Sleep Disorders
1.Sleepwalking: blank stare, move about in a slow/automatic
manner and may
try to eat, dress, or go to the
bathroom in the wrong place
 occurs in stage 4 sleep
 technical name…somnambulism
2.REM Behavior Disorder (RBD):
muscles not paralyzed in REM, allowing person to act out
their dreams (usually the vivid, violent, intense dreams)
 Seen more often in middle-age/elderly men,
sometimes linked with Parkinson’s disease
Dreams
Usually story-like
unfolding mental
imagery – most
commonly dreams have
some degree of likeness
to daily activities, yet
tend to be more bizarre
and unrealistic
What do we Dream?
What are some common
themes in YOUR
dreams?
Have you ever had a
recurring dream?
Dreams Questionnaire…
●1000 Psychology Today readers
responded…
o95% said they remembered their dreams
o39% said they could control their dreams
o68% said they had a recurring dream
o28% said they had died in a dream
o45% said they had dreamed about celebrities
Why do we dream?
1.Wish Fulfillment: Sigmund Freud suggested the
dreams provide a safety valve to discharge
unconscious wants & desires.
o The manifest content (remembered story-line) is a
censored version of the dream’s latent content
(underlying meaning of dream)
2.Information Processing: Dreams may help sift,
sort, and fix day’s experiences in our memories.
Why do we dream?
1.Physiological Function:
Dreams provide sleeping
brain with periodic
stimulation to develop and
preserve neural pathways.
Neural networks of
newborn are fast
developing therefore need
more sleep.
Why do we dream?
1.Activation-Synthesis Theory: Suggests that the
brain engages in a lot of neural activity that is
random. Dreams make sense of this activity.
 dreams are the
brain’s interpretations
of its own activity
 SO… they mean
NOTHING!!!
Why do we dream?
1.Cognitive Development: Some researchers
argue that we dream as a part of brain
maturation and cognitive development.
All dream researchers believe we need REM sleep.
When deprived of REM sleep, and then allowed to sleep,
we show increased REM sleep called REM Rebound.
Dream Theories
Summary