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

What has caused us to stay up later and force ourselves awake in the morning?

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 3– Transition to stage 4– Recognized by the beginning of delta waves

on EEG

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

REM Sleep

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

Dreams

• Theoretically based

• Freud and driven unconscious

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…

Physiological function

• Brain stimulation during REM = develop and preserve neural pathways

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

Hypnosis

Can anyone experience hypnosis?

• Yes!– Well, sort of – it’s called suggestion

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.

How does it work?

• Hypnosis is a divided consciousness– According to some or most or any or none

• Dissociation: a split in consciousness which allows some thoughts and behaviors to occur simultaneously with others– Remember selective attention?