sleep as a state of consciousness even when you are deeply asleep, your perceptual window is not...
TRANSCRIPT
Sleep as a State of Consciousness
• Even when you are deeply asleep, your perceptual window is not completely shut
–What is our evidence of this?
Biological Rhythms and Sleep
• Circadian Rhythm– 24 hour cycle of day and night through our
biological clock• Body temp rises, peaks, dips, and drops• Thinking is sharpest at peak
• Why is pulling an all-nighter a TERRIBLE idea?
So what’s going on here…
• Let’s take a second to go back to the eye/brain relationship
1. Bright light tweaks circadian clock by activating light sensitive retinal proteins
2. Proteins control circadian clock triggering suprachiasmatic nucleus (SCN) in the ____________
3. SCN causes brain’s pineal gland to decrease production of melatonin (sleep-inducing hormone) in mornings and increase in evenings
Sleep Stages
• Considered different state of consciousness because different parts of brain’s cortex stop communicating
• Still-active sleeping brain has its own biological rhythm
• Which brain scan is used most in sleep studies?
Sleep
• Need for sleep varies with individuals– 20 hours for infants– 6 hours for adults in their
70’s
Stage 0: A person is relaxed with eyes closed
• EEG shows alpha waves
• “falling asleep” called hypnagogic state– Lucid dreaming
• “waking” period is called hypnopompic state– just ten more minutes…
Quiet Sleep: NREM sleep
• Stage 1 lasts from 30 secs to 10 min– Characterized by sensory images and slow
rolling eye movements– Appearance of theta waves on EEG– May experience hallucinations
• Sensation of falling• Most alien abductions happen here
Quiet Sleep
• Stage 2 lasts 20 minutes – theta waves, sleep
spindles, and K-complexes on EEG
– Sleep spindles: bursts of rapid, rhythmic brain wave activity
– Sleep talking occurs most here
– You are now full on asleep
Quiet Sleep
• Stage 4– Deep sleep– Lasts 30 min, recognized by 20-50% delta
waves in EEG
**AMOUNT OF TIME SPENT ON STAGES 3 AND 4 VARIES AS NIGHT PROGRESSES**
Active Sleep: REM
• Nearly all dreams occur in REM• Dreams are more vivid and story-like than in
earlier stages• REM increases during the night
– Less than a minute to over an hour– 25% of the night’s sleep
• Causes atonia which is temporary paralysis of the body
• Brain is active while body shows loss of muscle tone
During REM Sleep
• Heart rate rises• Breathing becomes rapid and irregular• Eyes dart around• Genitals become aroused
– Erections/vaginal lubrication and clitoral engorgement (not dependent on sexual nature of dream)
– Men’s erection upon waking stems from the night’s last REM
– Typical 25 year old male erections happen for half the night
How are you “active” yet not…
• Brain’s motor cortex is running…
• Brainstem blocks the messages– Muscles relaxed (essentially paralyzed)
• REM is called paradoxal sleep– Internally aroused, externally calm
• So, how is it that arousal happens when we sleep?
Sleep Cycle
• Repeats about every 90 minutes• Night progresses, deep stage 4 gets
briefer and disappears– REM and stage 2 get longer
• By morning, 20 to 25% has been REM– Everyone dreams, we don’t remember most of
what we dream– What are the dreams called that we most
remember?
Why do we sleep?
• Without sleep our bodies deteriorate– Functionality/productivity– Aging– Weight gain and metabolism– Suppress immune cells (infections/cancer)– Memory impairment
Wait… hold up… you said weight gain?
• Sleep deprivations increases hunger-arousing hormone – gherlin – and decreases hunger-suppressing hormone – leptin– Increases appetite and eating – Also increases stress hormone – cortisol
Sleep Disorders
• Insomnia• Narcolepsy http://www.youtube.com/watch?v=-zVCYdrw-1o
• Apnea• Parasomnias
– SIDS– Jet lag– Sleepwalking (Somnambulism)– Bruxism
Freud’s wish-fulfillment
• Psychic safety valve– Safe place to express unacceptable feelings– Hidden meanings
– On The Interpretation of Dreams
Information-processing
• Dreams help sort the day’s events and consolidate our memories– That story about the place with the guy that
did the stuff… oh crap I lost it…
Activation-synthesis
• REM triggers neural activity to evoke random memories which our brain weaves into stories– Ever had a dream about the first house you
lived in or a childhood occurrence?
Cognitive development
• Dreams reflect individual’s knowledge and understanding of the world around them– Some take it WAY to seriously
Can hypnosis be theraputic?
• Maybe kinda sorta not really but in only in some cases…
– Posthypnotic suggestion has been found to alleviate headaches, asthma, stress-related disorders
• How about pain?– Hmmmm that’s up for debate.