81 WHAT IS SLEEP Sleep Periodic natural loss of consciousnessas distinct from unconsciousness resulting from a coma general anesthesia or hibernation Adapted from Dement 1999 Sleep and Dreams ID: 718238
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Slide1
Module 8
Sleep and DreamsSlide2
8-1:
WHAT IS SLEEP?
SleepPeriodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation (Adapted from Dement, 1999).
Sleep and DreamsSlide3
8-2:
HOW DO OUR BIOLOGICAL RHYTHMS INFLUENCE OUR DAILY FUNCTIONING?
Biological rhythms
24-hour biological clock
90-minute sleep cycle
Circadian rhythmInternal biological clock of 24-hour cycle of day and nightAs morning approaches, body temperature rises, peaks during day, dips in early afternoon, and begins to drop in eveningAltered by age and experience
Biological Rhythms and SleepSlide4
8-3:
WHAT IS THE BIOLOGICAL RHYTHM OF OUR SLEEPING AND DREAMING STAGES?
Four distinct stages, about every 90 minutes, including REM sleep (rapid eye movement sleep),
first discovered in 1952 with these observations
:Periods of fast jerky eye movementsEnergetic brain activity accompanies theseAwakened people report dreaming during these periodsSleep StagesSlide5
Sleep researchers
measure brain
-wave
activity, eye
movements, and muscle tension by electrodes that pick up weak electrical signals from the brain, eyes, and facial muscles. (From Dement, 1978.)
Measuring Sleep ActivitySlide6
EEG recordings showing brain activity:
Alpha waves:
slow waves of awake but relaxed stateTransition to sleep marked by slowed breathing and irregular brain waves: non-REM stage 1 sleep (NREM-1 sleep)Experience of hallucinations and hypnagogic
sensations during NREM-1 sleep
Leads to rapid, rhythmic brain activity: sleep spindles
(NREM-2 sleep)Then a transition to deep sleep with large, slow delta waves (NREM-3 sleep)
Sleep StagesSlide7
About
an hour after you first fall asleep, you ascend from your initial sleep
dive, returning through NREM-2 sleep to REM sleep.Each about 10 minutes; 20 to 25 percent
of sleep
Heart
rate rises, breathing becomes rapid and irregular, and every half-minute or so your eyes dart aroundDreaming occurs during these periodsGenitals aroused, regardless of dream’s content (except for very scary dreams)REM sleep is paradoxical
sleep
:
The body is internally aroused, with waking-like brain activity, yet asleep and externally calm
Sleep Stages
:
REM SleepSlide8
BRAIN WAVES AND SLEEP STAGES
Beta
waves of an alert,
waking state
and the regular alpha waves of an awake
, relaxed
state differ from the slower, larger
delta waves
of deep NREM-3
sleep.
Although
the
rapid REM
sleep waves resemble the near-
waking NREM
-1 sleep waves, the body is more
aroused during
REM sleep than during NREM sleep.
SleepSlide9
REM (rapid eye movement)
Rapid brain waves as though person is awake
Vivid dreams commonly occur during this stage.Genitals aroused during REM sleep, even when dream content is not sexualMotor cortex is active, but brainstem blocks messages
20-25 percent of average night’s sleep is REM sleep.
REM SleepSlide10
The
Stages in a Typical Night’s
SleepSlide11
8-4:
HOW DO BIOLOGY AND ENVIRONMENT INTERACT IN OUR SLEEP PATTERNS?
Sleep patterns are genetically and culturally influenced.Bright morning light activates light-sensitive retinal proteins. These trigger the suprachiasmatic
nucleus (SCN)
to
cause the pineal gland to decrease production of melatonin, a sleep-inducing hormone.Melatonin production increases at night.Modern lighting, lifestyles, and diversions may lead to sleep deprivation. As with waking behavior, biology and environment interact.
What Affects Our Sleep Patterns?Slide12
The biological clock
: Light
striking the retina signals the suprachiasmatic nucleus (SCN) to suppress the pineal gland’s production of the sleep hormone melatonin. At night, the SCN quiets down, allowing the pineal gland to release melatonin into the bloodstream.
What Affects Our Sleep Patterns?Slide13
8
-5
: WHAT ARE SLEEP’S FUNCTIONS?Sleep may have played a protective role in human evolution by keeping people safe during potentially dangerous periods. Sleep also helps restore and repair
damaged neurons.
REM and NREM-2 sleep help
strengthen neural connections that build enduring memories. Sleep promotes creative problem solving the next day. During deep sleep, the pituitary gland secretes a growth hormone necessary for muscle development.Why Do We Sleep?Slide14
8-6:
HOW DOES SLEEP LOSS AFFECT US, AND WHAT ARE THE MAJOR SLEEP DISORDERS?
Sleep deprived college and university students report:Feeling tiredHaving little energyConflicts in friendships and romantic relationshipsDepression
Function below their peak
Sleep Deprivation and Sleep Disorders
Effects of Sleep LossSlide15
Lack of sleep also associated with:
Weight
gainSuppressing immune cells that battle
infections
and diseases
Decreasing the life spanAccident pronenessInability to pay attentionSleep Deprivation and Sleep Disorders
Effects of Sleep LossSlide16
How Sleep Deprivation Affects UsSlide17
Insomnia:
Recurring
problems in falling or staying asleepNarcolepsy: Sudden uncontrollable sleep attacks, with sufferer sometimes lapsing directly into REM sleepSleep apnea: Stopping of breathing while asleep and repeated momentary
awakenings;
associated with obesity, especially in overweight men
Night terrors: High arousal and appearance of being terrified, target children during first few hours of NREM-3 sleepSleepwalking and sleeptalking (mostly childhood disorders): Occur during NREM-3 sleep; diminish with age
Major Sleep DisordersSlide18
Some Natural Sleep Aids
Sleep DisordersSlide19
Sequence of
images, emotions, and thoughts passing through a sleeping person’s mind
Dreams are generally difficult to remember; even those that momentarily awaken us are generally forgotten by morning.Dream story lines generally incorporate traces of
previous
days’ nonsexual experiences and
preoccupationsDreamsSlide20
8-7: WHAT DO WE DREAM?
We
usually dream of ordinary events and everyday experiences, most involving some anxiety or misfortune.While daydreams tend to involve familiar details of
our life, REM dreams are vivid ,
emotional
, and often bizarre—so vivid we may confuse them with realityFor both men and women, 8 in 10 dreams are marked by at least one negative event or emotionDreams with sexual imagery occur less commonly than believed, with one study finding just 1 in 10 among young men and 1 in 30 among young women
Dreams incorporating previous days
’ experience are the most common
What
We DreamSlide21
To reflect cognitive development
To make sense of neural static
To develop and preserve neural pathways
To file away memories
To satisfy our own wishes
Why we dream
8-8:
WHAT FUNCTIONS HAVE THEORISTS PROPOSED FOR DREAMS?
Why We
DreamSlide22
Dream Theories