Variations in Consciousness Chapter 5 Variations in Consciousness

On the Nature of Consciousness Consciousness – Awareness of internal and external stimuli Your awareness of external events Your awareness of your internal sensations Your awareness of your self as the unique being having these experiences Your awareness of your thoughts about these experiences

Consciousness and Brain Activity Electroencephalograph (EEG)- Device that monitors the electrical activity of the brain over time by means of recording electrodes attached to the surface of the scalp. Variations in consciousness are measured using an EEG. Brain waves – line tracing that indicates the rhythm of cortical activity Amplitude – height Frequency – cycles per second (cps)

EEG Patterns EEG Pattern Frequency (cps Typical States of Consciousness Beta 13-24 Normal waking thought, alert problem solving Alpha 8-12 Deep relaxation, blank mind, meditation Theta 4-7 Light sleep Delta Less than 4 Deep sleep

Biological Rhythms and Sleep Biological Rhythms – Periodic fluctuations in physiological functioning Internal “biological clocks” that monitor the passage of time Biological rhythms are reflected through the following as well as various others: Daily alteration of light and darkness Annual patterns of the seasons Phases of the moon

The Role of Circadian Rhythms Circadian Rhythms- The 24 hour biological cycles found in humans and many other species Influential in the regulation of sleep People generally fall asleep when their body temperature begins to drop and awaken once it begins to increase again Light enters retina Receptors in retina send information to suprachiasmatic nucleus in the hypothalamus SCN sends signals to pineal gland Pineal gland secretes melatonin Melatonin plays a key role in adjusting biological clocks

Ignoring and Realigning Circadian Rhythms Consequences of Ignoring Circadian Rhythms Quality of sleep suffers Causes Jet Lag (It’s easier to fly Westward and lengthen your day than it is to fly Eastward and shorten your day) Feel fatigued, sluggish, and irritable Realigning Circadian Rhythms Doses of melatonin Exposure to bright light Carefully plan rotation schedules Readjustment for Jet Lag takes 1 day for each time zone crossed when flying Eastward and 2/3 when flying Westward

The Sleep and Waking Cycle Devices used to study sleep and wake cycles Electromyograph (EMG) – Records muscular activity and tension Electrooculograph (EOG) – Records eye movement Electrocardiograph (EKG) – Records the contractions of the heart Other instruments are used to monitor body Temperature, breathing, and pulse rate.

Cycling Through the Stages of Sleep The average length of time that it takes for people to fall asleep is approximately 25 minutes Stage 1 is a brief transitional stage of light sleep that lasts only 10-12 minutes Breathing and heart rate decrease Muscle tension declines Body temperature declines Lower frequency EEG activity Theta waves are prominent

Cycling Through the Stages of Sleep Stages 2, 3, and 4 Respiration, heart rate, muscle tension, and body temperature continues to decline Brain waves become higher in amplitude and slower in frequency Move into slow-wave sleep Slow-wave sleep – consists of sleep stages 3 and 4, during which low frequency delta waves are prominent in EEG Recordings Reach slow-wave sleep in approximately one hour and remain there for half an hour Cycle begins to reverse itself

Cycling Through the Stages of Sleep REM Sleep REM – Rapid Eye Movement REM sleep is reached when sleep cycle is reversed and you reach what should be stage 1 Deep stage of sleep Difficult to awaken a person at this stage Marked by irregular breathing and pulse rate Muscle tone is extremely relaxed EEG dominated by high frequency beta waves resembling the alert and awake state

REM & NREM Sleep REM Sleep Deep stage of sleep marked by rapid eye movements, high frequency brain waves, and dreaming Dreaming is most vivid, frequent, and memorable. Non-REM sleep (NREM) Consists of sleep stages 1-4, which are marked by an absence of rapid eye movements, relatively little dreaming,

Sleep Stages

Age, Culture, and Sleep Newborns sleep 6-8 times in a 24 hour period (appx. 16 hours per day) 50% of babies’ sleep is spent in REM sleep From adolescence on until later adulthood the average time spent in REM sleep is 20% With increased age, the percentage of time spent in stage 1 sleep increases slightly. There is a shift towards lighter sleep with increased age

Sleep Disorders Insomnia – chronic problems in getting adequate sleep Difficulty in falling asleep initially Difficulty in remaining asleep Persistent early morning awakening Narcolepsy – Disease marked by sudden and irresistible onset of sleep during normal waking periods. Goes directly from wakefulness into REM sleep Sleep apnea – frequent, reflexive gasping for air that awakens a person and disrupts sleep Occurs when a person stops breathing for a minimum of 10 seconds Somnambulism (sleepwalking) – Occurs when a person arises and wanders about while remaining asleep Mostly occurs during the first 3 hours of sleep and during slow-wave sleep Episodes may last anywhere from 15 seconds to 30 minutes