Consciousness - Sleep and Disorders (Introductory Psychology I - Fall 2024) PDF

Introductory Psychology I Fall 2024 Consciousness - Sleep and Disorders Learning objectives Define the concept of a circadian rhythm, and explain its role in regulating sleep Describe the human sleep cycle, including the features of the 5 stages of sleep Describe what o...

Introductory Psychology I Fall 2024 Consciousness - Sleep and Disorders Learning objectives Define the concept of a circadian rhythm, and explain its role in regulating sleep Describe the human sleep cycle, including the features of the 5 stages of sleep Describe what occurs during various sleep disorders What is consciousness?  Consciousness can’t be What is consciousness? measured therefore it doesn’t exist Consciousness: Our subjective Consciousness experience of the world, our is self- awareness bodies, and our mental perspectives Consciousness is unitary Sleep, drugs, and other experience of an organism experiences can produce with a nervous system altered states of consciousness Consciousness is a vague concept that doesn’t need to be perfectly defined, only described to the What is sleep? Across species, sleep can be broadly defined as a “resting state” Sleep deprivation has been linked with just about every chronic health condition, ranging from cardiovascular disease, diabetes, cancer, and immune dysfunction Also implicated in disorders related to mental health such as anxiety, depression, and Alzheimer’s Why do we sleep? Costs of sleep: Lost time that could be spent doing other things Vulnerability Benefits of sleep?: Making robust and appropriate neuronal connections, including those that are required for development (e.g., learning, memory, emotional processing, brain maturation) Overall maintenance of body (protein synthesis increases, neurotransmitters regenerated, cell division rate increases) Sleep is as fundamental to animal life as seeking food and reproduction Thus, it appears that sleep is a universal requirement of having an organized nervous system The individual decision to sleep Determined by internal, external, and physiological factors  Circadian Rhythms Behavioral and physiological changes in an organism that adhere to a 24-hour cycle Regulated by changes in genetic expression through the day by proteins that function as “biological clocks” Changes in these proteins affect hormone levels, metabolic processes and body temperature. They share genetic and functional characteristics across a broad and diverse range of organisms Circadian Rhythm regulation Light is the primary cue for circadian regulation across taxa How much time a species allots to sleep during a 24-hour period is shaped by evolution based on feedback loops and homeostatic mechanisms regulated by melatonin The timing of sleep is part of an organisms’ circadian rhythm Human Circadian Rhythms Typically, we tend to be most mentally alert mid- morning, but our physical activity is best mid- afternoon Around 9 pm, we become sleepy Our deepest sleep occurs in the early morning hours as our body temperatures are at their lowest at around 4:30 am How to describe sleep? Three major factors that characterize sleep: 1) Length of sleep 2) Ratio of NREM to REM sleep 3) Timing of sleep Across the tree of life, the allotment and timing of sleep reflects a species ecological and physiological constraints Factors that influence sleep patterns across species Nervous system complexity Dietary patterns Body size Sociality Life history Human Sleeping Patterns There is variability among cultures and individuals as to how sleep is distributed Some sleep at night in a more- or-less continuous stretch. Others’ sleep is biphasic, with a chunk at night and a daytime nap There also is variability in sleep patterns throughout the lifetime of an individual  The human sleep cycle Non-REM sleep: Physiological processes and brain waves slow down. Important for cellular maintenance, development, and tissue repair REM sleep: Characterized by brain waves that are more similar to waking state and rapid eye movement under closed eyelids. Muscles become immobilized, and dreaming may occur. Thought to be especially important for memory consolidation and emotional processing Alternations between NREM and REM sleep occurs over a series of cycles throughout the night How we measure sleep: Brain Waves The frequencies of waves recorded in an EEG reflect electrical activity, voltage patterns, that vary with brain activity A busy awake brain shows high frequency (beta), and somewhat chaotic, waves. A brain in deep sleep shows low frequency, slow waves, called delta waves. A dreaming brain exhibits activity that looks more like an awake brain NREM Stage I: Light sleep The first is Stage I, switching from wakefulness to sleep Brain waves slow (theta waves) as do general physiological functions The sleeper may experience jerky movements and hallucinations. This pattern is also characteristic of a daydreaming brain Hypnagogic Imagery: scrambled, bizarre, and dream-like images that flutter in and out of consciousness NREM Stage II: Light sleep Stage II is light sleep and is characterized by theta waves, generated by thalamic activity, with intermittent sleep spindles and K-Complexes Sleep spindles are thought to be necessary memory consolidation of “facts” and K Complexes are associated with memory consolidation and ignoring external stimuli. K-complex are only observed during sleep. Body temperature drops, heart rate slows, muscles relax and eye movements stop 65% of sleep  NREM Stage III/IV: Deep sleep Stage III/IV sleep, also known as slow-wave sleep and deep sleep, is required for “refreshment” or physiological renewal Physiological processes slow even further and subjects are difficult to wake in this stage NREM Stage III is also thought to be important for memory consolidation. Some researchers suggest Stage IV, much like Stage III, is when tissue repair may be happening Suppressed by alcohol Stage 5: REM Sleep REM sleep is characterized by brain waves (alpha and beta) similar to those when awake and by rapid eye movements under eyelids Breathing and heart rate goes up. Voluntary muscles become immobilized. This is when we experience dreams Robust brain activity coupled with an immobilized body is termed paradoxical sleep Discussion break: Do you ever consider that you don’t get enough sleep at night? If so, have you made efforts to improve your sleep “hygiene”? Did you see improvements? Major evolutionary factors behind many Sleep Disorders: Evolutionary mismatch: The environments we live in now are drastically different than the environments our ancestors evolved in (i.e., mismatched) Many sleep disorders are likely impacted by mismatches: Those related to anxiety (hectic life styles!) Availability of technology Artificial light Misunderstanding of sleep cycles throughout one’s lifetime, being forced to be awake during certain schedules Insomnia Persistent difficulty with sleep initiation, duration, consolidation or quality Two primary symptoms: 1) Sleep difficulties even when there are sufficient opportunities for sleep 2) Decreased daytime function due to poor sleep quality or duration Various forms of insomnia For some, it may be hard to stay asleep or fall asleep in the first place For others, waking up occurs after falling asleep and is awake for several hours before falling back asleep again (or not at all) Most adults experience acute insomnia, lasting for days or a week or two, at some point in their lives. Chronic insomnia is defined by clinicians as having three nights of bad sleep a week for three months! Physiological basis of insomnia: A symptom of anxiety (and sometimes mood disorders) In part, can be influenced by bright light close to bedtime, caffeine and alcohol, too warm a room, exercise too close to bedtime and inconsistent bedtime However, chronic insomnia (where the patient can’t seem to fall asleep in the first place) is often directly the result of chronic stress and anxiety Seasonal affective disorder: A circadian rhythm disorder? SAD (symptoms of depression during winter that go away during summer) is more prevalent in people living at northern latitudes, and in people who descend from populations from northern latitudes Likely represents a “shift” in circadian rhythm to deal with the drastically different day lengths This is supported by symptoms being strongest in the morning, and light exposure therapy often an effective Mismatches and insomnia Light, especially blue blight, disrupts the secretion of melatonin, a hormone important in regulating our circadian rhythm Chang et al., 2014  Narcolepsy Narcolepsy is a rare disorder (about 0.02% of the population) Characteristics are: 1) Overwhelming bouts of sleepiness during the day; they are essentially sleep “attacks” 2) Paralysis upon waking/falling asleep. Can be accompanied by hallucinations 3) Sudden loss of muscle control, cataplexy, usually triggered by emotions. Paradoxically, the person/animal remains awake. Physiological basis of narcolepsy: A symptom of autoimmune disease Assays show low levels of brain hormones (orexins) that associated with wakefulness and arousal Loss of cells in the hypothalamus that produce orexins, likely due to autoimmune destruction of these cells Is narcolepsy an “evolutionary hangover?” “Tonic immobility”, or feigning death is a cataplexic state that some animals use a defense strategy. There are neurological similarities between this state and narcolepsy Other sleep disorders Sleep apnea Night terrors Sleep walking  Some recommendations for better sleep (Matt Walker, Why We Sleep) Try to go to bed and get up the same time each day Avoid caffeine, nicotine and alcohol late in the day Don’t eat heavy meals close to sleep Daily exercise is good, but not close to bed time Relax before going to bed: read, knit, take a warm bath, pet dog, meditate, etc A slightly cool room temperature No screen time before bed (and as little light in general) Try to get some sunlight as soon as you wake up  Introductory Psychology I Fall 2024 Consciousness - Dreams and other Altered States Learning Objectives Describe and compare three theories of dreaming (Dream protection theory, activation synthesis theory, and neurocognitive theory) Understand how “unusual” alterations to consciousness, such as near out of body, near- death, and mystical experiences occur Describe some common myths related to hypnosis and explain two hypothesis that might explain what is occurring Why do we dream? Byproduct hypotheses: Processing emotional memories Integrating new experiences with established memories Reorganizing and consolidating memories Evolutionary hypotheses: Learning new strategies and ways of doing things Simulating threatening events so we can better cope with them in everyday life  Freud’s theory of unconsciousness Unconsciousness: Body of mental activities unavailable for direct reflection, but that influence conscious processes and behavior Pleasure principle Drive to have instinctive urges and desires satisfied Characteristic of the unconscious Reality principle Recognition of environmental constraints on behavior Adjustment and control of behavior Characteristic of the conscious Freud’s Dream Protection Theory The Interpretation of Dreams (1899) Concluded that dreams represent wish fulfillment and symbolic attempt to realize an unfulfilled desire Trauma and shameful desires must go somewhere  unconscious reservoir of repressed desires and memories, that sometimes come out in dreams Two types of content: Manifest content – the plot of a dream; the way its remembered Latent content – the hidden content of a dream; what it symbolizes Evaluation of Freud’s Dream Protection Theory Rejected by most scientists due to lack of evidence Very few sexual dreams (