“normal” state - being awake Other states - daydreaming,
dreaming, hallucinations, starvation, sensory deprivation, hypnosis, meditation
Unconsciousness = parallel processing system (not Freud’s unopened box of childhood memories)
Biological Rhythms
Circadian rhythm - daily biological clock
Suprachiasmatic nucleus (SCN) in the hypothalamus senses light and controls clock
Circadian rhythm controls body temperature - rises in early morning, peaks during the day, dips in early afternoon, and drops at night
Circadian rhythms are affected by time changes, traveling across time zones, bright lights before bed
Because of electricity, most people today do not get enough sleep Cell phones/tablets also create light that
fools the SCN
Sleep
Sleep Cycles: Stages of Sleep The awake brain produces alpha
waves You don’t remember the moment
that you fall asleep Stages 1-4 are NREM sleep (non-
REM)
Figure 5.4 Brain waves and sleep stages The regular alpha waves of an awake, relaxed state are quite different from the slower, larger delta waves of deep Stage 4 sleep. Although the rapid REM sleep waves resemble the near-waking Stage 1 sleep waves, the body is more aroused during REM sleep than during Stage 1 sleep.
From Dement, 1978
© 2010 by Worth Publishers
Stage 1
Stage 1 sleep often includes hallucinations (dreams with no plot), includes the hypnagogic sensations of
falling or weightlessness Stage 1 is short (less than 20
minutes)
Stage 2
Brain waves have “sleep spindles” - bursts of rapid, rhythmic activity
Sleeptalking may happen here Lasts about 20 minutes
Stage 3
Transitional, short Delta brain waves begin (large and
slow)
Stage 4
More delta waves Deep sleep - harder to wake
someone up from Sleepwalking and bedwetting
typically happen here, mostly in children
REM sleep
After 4, you go back through stages 3 and 2 to Rapid Eye Movement sleep
Brain waves are similar to stage 1, but breathing and heart rate increase and eyes move
Motor cortex is active but brainstem blocks its signals (leaving you basically paralyzed)
REM sleep cont.
Dreams happen in REM sleep Unlike stage 1, these are typically
emotional, detailed, and have a continuous plot
REM is “paradoxical sleep” - brain waves look active but body is very relaxed
Sleep Cycle
Sleep cycles last about 90 minutes After the first cycle, stage 1 is
replaced with REM As the night goes on, you have less
of stages 3 and 4 and more REM
Figure 5.6 The stages in a typical night’s sleep Most people pass through the five-stage sleep cycle (graph a) several times, with the periods of Stage 4 sleep and then Stage 3 sleep diminishing and REM sleep periods increasing in duration. Graph b plots this increasing REM sleep and decreasing deep sleep based on data from 30 young adults.
From Cartwright, 1978; Webb, 1992
© 2010 by Worth Publishers
Do We Need Sleep?
People can stay awake for about 8 to 10 days, but higher-level functions such as concentration and perception are significantly affected
Rats and people who go more than two weeks without sleep die
Effects of Sleep Loss
Diminished productivity and concentration
Irritability Increased production of stress
hormone cortisol, which stimulates production of body fat
Increased production of hunger hormone ghrelin (and decrease of leptin, which suppresses hunger)
Suppresses immune system’s capacity to fight of viral infections and cancer
Slower reaction time More errors on visual and memory
tasks Changes to metabolic and endocrine
systems that mimic aging
How much sleep do we need? Infants and young children need
more than adults Most adults will sleep 7.5-9 hours per
night when they have no restrictions Our brains track “sleep debt” for at
least two weeks
Theories on Sleep
Sleep protects us - keeps us from running around in the dark
Sleep helps us recuperate - repair brain tissue from free radicals
Sleep helps memory - memories of the day’s new info are built and stored during sleep
Sleep boosts creativity - people are more insightful at problem solving with more sleep
Sleep helps physical growth - pituitary gland releases growth hormone during sleep
Sleep Disorders
Insomnia - consistent inability to sleep Sleeping pills and alcohol can make it
worse Natural solutions:
Exercise Avoid caffeine Relax in dim light Sleep on a consistent schedule and don’t
spend more than 7 hours in bed
Narcolepsy - uncontrollable “sleep attacks” where patients drop in to REM
Attacks usually last less than 5 minutes but may happen at any time
Genetic cause identified (affects 1 in 2000 people)
Sleep apnea - temporarily stop breathing during sleep
Lack of oxygen wakes patients up throughout the night, preventing them from reaching delta-wave sleep
Symptoms: terrible snoring, wake up feeling tired
Linked to obesity, cured with a mask that forces air through nose
Night terrors - not the same as nightmares
Typically happen to children in stage 4 sleep, often not remembered by child
Child may scream, breath quickly, sit up, and/or speak, without waking up
Sleepwalking - runs in families, mostly affects children
Typically not dangerous, many people return to bed on their own
Happens during stage 4 sleep
Dreams
Content of Dreams
Manifest content (Freud’s idea) - what actually happens in a dream
More commonly negative than positive
Trauma commonly causes nightmares
Dream content varies with culture Often includes details from the day
or things we’re worried about
Theories on Dreams
Freud: to satisfy our wishes in a safe, socially acceptable way
Believed dreams are symbolic versions of latent content (unconscious motives and sexual desires) that could be analyzed to learn about someone’s unconscious
No longer considered scientific
Dreams may help us file away memories by processing new information
Dreams may develop and stimulate neural pathways (infants spend more time in REM sleep than anyone else)
Dreams may make sense of neural static - random neural firing may be interpreted as dreams (activation synthesis theory) Dreams activate visual processing areas
and the emotional limbic system Dreams reflect cognitive
development Use language and other skills as children
learn them
REM sleep is biologically necessary Animals/people deprived of REM
sleep will have “REM rebound” when they are allowed to sleep unrestricted
REM occurs in mammals and may reflect the ability to learn
More than one theory of dreaming may be true
Addiction
Addiction can be physical (withdrawal causes pain or cravings) or psychological (usually for stress-relieving drugs)
Addiction take time to develop and some people never develop one
While therapy to overcome addiction is usually helpful, it is not necessary for everyone
Addiction was traditionally used to talk only about substance abuse (drugs/alcohol)
Can you be addicted to things like food, the Internet, video games, gambling, etc? Or does this just give people an excuse?
Influences on Drug Use
Biological: Having an identical twin puts the other
twin at higher risk for alcohol dependence and marijuana use than a fraternal twin
Mice can be bred to prefer alcohol to water
Researchers are investigating genes that contribute to addiction
Psychological influences: Feeling that one’s life is meaningless Depression, low self-esteem, abuse, or
loneliness Social-cultural influences:
People do it at parties (to be social) Actions of friend group Some religions discourage drug/alcohol
use Cities have higher rates than rural areas