ON THE NATURE OF CONSCIOUSNESS What is consciousness? In short, we can say it’s our awareness of ourselves and our environment → this includes awareness of external events, internal sensations, your self as a unique being, and your thoughts about it all

A BRIEF HISTORY OF CONSCIOUSNESS Wundt declared psychology to be the study of consciousness and the structuralists analyzed its basic parts → James and the functionalists called it a ‘stream’ and looked at its purpose/function → Freud and his psychoanalytic approach focused instead on the unconscious

A BRIEF HISTORY OF CONSCIOUSNESS → Watson, Skinner and the behaviorists said consciousness is not objective and not worthy of scientific study → the cognitive and neuroscientific approaches brought consciousness back under the microscope in the 1950s

CONSCIOUSNESS AND THE BRAIN EEGs (electroencephalographs) measure brain activity in terms of brain waves varying in amplitude (height) and frequency (cycles per second, cps) → brain wave activity is divided into four categories (from fastest to slowest): beta, alpha, theta and delta

CONSCIOUSNESS AND THE BRAIN These categories are loosely associated with different levels of consciousness: beta when you are alert, alpha when your’re relaxed, theta during light, and delta during deep, sleep

CIRCADIAN RHYTHMS Our Circadian Rhythms are our biological clock; the regular bodily rhythms (temperature/wakefulness) that occur on a 24-hour cycle

CIRCADIAN RHYTHMS → our 24-hour biological clock is reset each day when light signals the retina to send inputs to the suprachiasmatic nucleus (SCN) in the hypothalamus, which then sends a signal to the pineal gland to decrease sleep-inducing melatonin

CIRCADIAN RHYTHMS → disrupting your biological clock by flying across time zones (jet lag) or working rotating or late-night shifts diminishes quality of sleep

THE SLEEP AND WAKING CYCLE Sleep activity is monitored using electrodes to measure brain activity, eye movements, muscle tension, heart/pulse rates and temperature → we initially cycle through four distinct stages (not 5 like your books says) of sleep, beginning with NREM stage 1 * NREM sleep refers to non-REM sleep stages 1-3 when there is no REM, few dreams, and varied brain activity

THE SLEEP AND WAKING CYCLE

THE SLEEP AND WAKING CYCLE NREM -1 (Stage 1) sleep is brief (10-12 minutes) and is characterized by theta waves and hypnic jerks → we can’t recall the exact moment we fall asleep, but our brain waves show the exact instant

THE SLEEP AND WAKING CYCLE NREM-2 (Stage 2) sees the sleeper’s breathing and heart rate, muscle tension, and body temperature continue to decline → during the roughly 20-minutes of NREM-2 sleep spindles occur – bursts of rapid brain-wave activity

THE SLEEP AND WAKING CYCLE NREM-3 sleep (stage 3) is deep sleep that lasts about 30 minutes and is characterized by large, slow delta waves – it’s tough to wake a stage 3 sleeper → after NREM-3 the cycle reverses itself and we go back to NREM-2

THE SLEEP AND WAKING CYCLE Instead of going back to NREM-1, we enter REM sleep marked by rapid eye movement and heart rate, irregular breathing and relaxed muscles to the point of paralysis → beta-wave brain activity (alert) in REM is linked to the fact that we dream deeply and often during REM

THE SLEEP AND WAKING CYCLE Our 90-minute sleep cycle is repeated throughout the night, with NREM-3 getting shorter and disappearing and REM periods getting progressively longer

SLEEP AND AGE

WHY SLEEP? Neurologically, sleep depends on an interactive process throughout the brain involving the reticular formation, the pons and adjacent areas of the midbrain → theories of why we sleep include: 1) it protects us from predators, 2) it helps us conserve energy, 3) it helps us rebuild and recover

SLEEP DEPRIVATION Partial sleep deprivation has significant negative effects including decreased attention-spans, reaction time, mental acuity, motor coordination and decision-making → specific health-related problems (possibly) associated with deprivation include: 1) obesity, 2) immune system malfunctioning, and 3) susceptibility to diabetes, hypertension, and cardiovascular disease

SLEEP DEPRIVATION Selective deprivation studies (depriving subjects of REM or slow-wave sleep) show that losing these stages results in extra time spent in them when normal sleep resumes (REM rebound) → theories of why we need these specific stages include: 1) it contributes to memory consolidation, 2) it aids in neurogenesis (forming new neurons), 3) it feeds creative thinking