Consciousness:

n Awareness of the outside world and/or one’s own mental activity (sensations, feelings & thoughts).

n Really a “continuum of consciousness” which varies throughout the day

u Degree of arousal/alertness and awareness

u Focus (internal vs external)

u Degree of active control we have over the state

n Most common dramatic shift in consciousness is sleep

Biological Rhythms:

n Regular cycles of behavior or physiological functioning

n Circadian rhythms - ~24 hr cycles in many biological processes and behaviors

n Regulated by biological clock in hypothalamus: the suprachiasmatic nucleus(SCN)

n SCN triggers release of melatonin from pineal gland in the evening

n This clock is set/reset by the daylight

Our sleep/waking rhythm is the most obvious of our circadian rhythms.

n Sleep research depended on the development of tools to monitor the details of sleep.

Polysomnogram

n EEG monitors brain waves

n EOG monitors eye movements

n EMG monitors muscle tension

n Sometimes additional measures

n All are indicated by pen markings on a rolling sheet of paper

2 Main Types of Sleep

n NREM Sleep (stages 1-4) (about 75-80% of night; includes the deepest stages of sleep (slow-wave sleep))

n REM (rapid eye movement) or Dream Sleep (20-25% of night)

Repeating Cycles of A Night’s Sleep

NREM Sleep

n gradual decrease in movements, breathing, heart rate, blood pressure

n brain waves become slow & rhythmical (“delta waves”)

n hard to wake up; might not remember being awakened

n sleep-thinking more common than dreams

REM Sleep

n very active brain waves similar to waking

n periodic rapid jerky eye movements

n total loss of tone in most muscles, effectively paralyzing you

n breathing, heart rate, BP unpredictable

n 80% chance of vivid dream report

n erections/vaginal lubrication regardless of dream content

Theories About REM Function

n REM sleep provides periodic activation of brain neurons during sleep

n Freud : dreams are a safe outlet for unconscious impulses or “wish fulfillment”

n Cartwright: Dreams are an extension of the processing/problem solving of waking life

n Activation synthesis theory - Dreams are just the brain’s attempt to make sense of spontaneous brain activity during sleep

REM Sleep Changes Over Lifespan

Why Do We Sleep?

n Repair or Restorative Theory: sleep allows the body and brain to restore itself

n Adaptive or Evolutionary Theory: sleep evolved because it conserved energy and helped avoid harm during dangerous time of day

n Other proposed functions: memory storage, immune activity, growth and brain development

Species Differences in Length of Sleep

Non-REM Sleep Disorders

n NREM sleep “disorders” are very common in kids and tend to run in families. Most outgrow them. A much smaller # of adults continue to have these disorders.

n Sleep-walking

n Night terrors (extreme fright and arousal but not truly awake; no recollection later)

n Bed-wetting (enuresis)

REM Sleep Disorders

n More rare than Non-REM problems

n Narcolepsy - REM sleep “attacks” with cataplexy, sleep paralysis, & hypnagogic hallucinations. Often triggered by emotion.

n REM sleep behavior disorder - failure of the usual muscle paralysis mechanism of REM so the person can move during dreaming

Other Sleep Disorders

n Many different types of insomnia & treatments

u Prescription sleep aids – mostly benzodiazepines except for Ambien & Sonata

u OTC sleep aids = antihistamine

n Sleep apnea - frequently stop breathing during sleep - risky to health & exhausting

u Most often due to throat closing during sleep

u CPAP - Constant positive air pressure delivered via face mask keeps throat open

The Sleep Deprivation Crisis

n 43% of adults moderately-severely sleep deprived and know it

n 50% adults say they get enough sleep, but:

n 63% experience sleep problems each week

n high school & college students are, for the most part, walking zombies

n Sleep deprivation costs $100 billion/yr

Sleep is a necessity, not a luxury

n Quality of sleep determines

u our mood, alertness, energy, thinking, productivity, and safety

u general health & longevity

n Sleeping brain is highly active and:

u regulates immune, hormone, and cardiovascular functions

u replenishes neurotransmitters

n We are abusing sleep (since 1879).

Consequences of Shortened Sleep

n Drowsiness; unintended sleep

n Increased irritability, anxiety, depression

n Decreased socialization & sense of humor

n Decreased cognitive &motor performance

n Decreased concentration, memory, problem-solving, creativity, decision-making

n Decreased quality of work & productivity

n Driving drowsy is as dangerous as DWI