Study Guide for Sleep
1.5a Sleep: Consciousness
1.5-1 Defining Consciousness
Consciousness - our subjective awareness of ourselves and our environment
After initially claiming consciousness as its area of study in the 19th century, psychologists had abandoned it in the first half of the 20th century, turning instead to the study of observable behavior because they believed consciousness was too difficult to study scientifically.
Since 1960, under the influence of cognitive psychology and neuroscience, consciousness (our awareness of ourselves and our environment) has resumed its place as an important area of research.
States of Consciousness
Occur spontaneously: daydreaming, drowsiness, dreaming
Physiologically induced: hallucinations, orgasm, food or oxygen starvation
Psychologically induced: sensory deprivation, hypnosis, meditation
Cognitive Neuroscience - the interdisciplinary study of the brain activity linked with cognition (thinking, knowing, remembering and communicating).
1.5-2 Dual Processing: The Two Track Mind
Blindsight - a condition in which a person can respond to a visual stimulus without consciously experiencing it.
Parallel Processing - processing many aspects of a problem simultaneously; generally used to process well-learned information or to solve easy problems
Sequential Processing - processing one aspect of a problem at a time; generally used to process new information or to solve difficult problems.
1.5b Sleep: Sleep Stages and Theories
1.5-3 What is Sleep - a periodic, natural loss of consciousness as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation.
1.5-4 Circadian Rhythm
Circadian Rhythm - your body's internal, biological clock. The typical human circadian rhythm occurs on a cycle of approximately 24 hours. However, the clock is not really functioning on time, but on body temperature. As morning nears, body temperature rises; it then peaks during the day, dips for a time in early afternoon, and begins to drop again in the evening. Sleep patterns shift with age. Owls become larks with children, menopause.
1.5-5 Stages of Sleep
Awake but relaxed: Alpha waves - the relatively slow brain waves of a relaxed, awake state. We cycle through four distinct sleep stages about every 90 minutes.
NREM 1 – slowed breathing and irregular brain waves; theta waves. During NREM 1 hallucinations (false sensory experiences that occur without a sensory stimuli) and hypnagogic sensations (bizarre experiences, such as jerking or a feeling of falling or floating weightlessly while transitioning to sleep). Easily awakened.
NREM 2 - lasts about 20 minutes; sleep spindles (bursts of rapid, rhythmic, brain-wave activity). Still able to be awaken. Theta waves.
NREM 3 – Delta waves (large, slow brain waves). Deep sleep. Lasts about 30 minutes. Difficult to awaken.
REM – Rapid Eye Movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep because the muscles are relaxed (except for minor twitches) but other body systems are active.
During a normal night's sleep, NREM-3 sleep shortens and REM and NREM -2 sleep lengthen. People pass through a multicycle sleep cycle several times each night, with the periods of deep sleep diminishing and REM sleep periods increasing in duration. As people age, sleep becomes more fragile, with awakenings common among older adults.
Being bathed in or deprived of light disrupts our 24 hour biological clock. Night shift workers may experience a chronic state of desynchronization.
Sleep paralysis - is a state, during waking up or falling asleep, in which a person is aware but unable to move or speak. During an episode, one may hallucinate (hear, feel, or see things that are not there), which often results in fear.
Paradoxical Sleep - Also known as REM sleep or dreaming sleep, paradoxical sleep is a distinct stage of sleep with intense brain activity in the forebrain and midbrain. It is characterized by dreaming and the absence of motor function with the exception of the eye muscles and the diaphragm.
1.5-6 What Affects Our Sleep Patterns
Sleep patterns are genetically influenced. Sleep patterns are also culturally influenced.
Suprachiasmatic nucleus (SCN) – a pair of cell clusters in the hypothalamus that controls the circadian rhythm. In response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness.
Melatonin - is a naturally occurring compound found in the body that has many vital functions; maintaining the circadian rhythm (sleep/wake cycles), light dependence, antioxidant functions, support of the immune system, and dreaming.
The biological clock - Light striking the retina signals the SCN to suppress the pineal gland's production of the sleep hormone melatonin. At night, the SCN quiets down, allowing the pineal gland to release melatonin into the bloodstream.
1.5-7 Sleep’s Functions
Sleep protects. Sleep may have played a protective role in human evolution by keeping people safe during potentially dangerous periods.
Sleep helps us recuperate - helps restore the immune system and repair brain tissue. Sleep helps restore and repair damaged neurons.
Sleep helps us restore and rebuild our fading memories of the day’s experiences - sleep consolidates our memories by replaying recent learnings and strengthening neural connections.
Sleep feeds creative thinking - dreams can inspire artistic and scientific achievements.
Sleep supports growth -ample sleep supports skill learning and high performance.
During slow wave sleep, the pituitary gland secretes a human growth hormone necessary for muscle development.
1.5-8 Sleep Deprivation
Sleep deprivation causes fatigue and irritability, and it impairs concentration, productivity, and memory consolidation. It can also lead to depression, obesity, joint pain, a suppressed immune system, and a slowed performance (with greater vulnerability to accidents).
1.5-9 1.Major Sleep Disorders
Sleep apnea - a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.
Narcolepsy – a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.
Night Terrors – a sleep disorder characterized by a high arousal and an appearance of being terrified; unlike nightmares, night terrors often occur during NREM 3 sleep, within two or three hours of falling asleep, and are seldom remembered.
Insomnia – ongoing difficulty falling or staying asleep. Most common sleep disorder.
Sleepwalking and sleep talking - Doing normal waking activities (sitting up, walking, speaking) while asleep. Sleep talking can occur during any sleep stage. Sleep walking occurs during NREM 3.
1.5-10 Dreams
Dream – a sequence of images, emotions, and thoughts passing through a sleeping person’s mind.
What We Dream
We usually dream of ordinary events and everyday experiences, most involving some anxiety or misfortune. Fewer than 10 percent of dreams among men, and fewer still among women, have any sexual content. Most dreams occur in during REM sleep. Those that happened during NREM tend to be vague, fleeting images. We spend six years of our life dreaming. Eight in ten dreams are marked by at least one negative event of emotion.
Trauma and dreams - after trauma, people commonly report nightmares. Sometimes aggression.
Musicians' dreams - compared with non-musicians, report 2x as many dreams of music.
Blind people's dreams - most dream using nonvisual senses. Sometimes see in the dream.
Media experiences and dreams - violent media = violent dreams.
Why We Dream
To satisfy our own wishes – Freud: Manifest Content (the symbolic, remembered storyline of a dream), Latent Content (the underlying meaning of a dream)
To file away memories (the information processing perspective)
To develop and preserve neural pathways
To make sense of neural static
To reflect cognitive development
REM rebound - the tendency for REM sleep to increase following REM sleep deprivation.
