Chapter 5: Consciousness, Sleep, and Psychoactive Drugs – Study Notes

Consciousness

Introduction to Consciousness

Consciousness refers to our awareness of ourselves and our environment. It encompasses a range of states, including wakefulness, sleep, dreaming, and altered states induced by drugs or hypnosis.

Sleep

Stages of Sleep

Sleep is divided into several stages, each characterized by distinct physiological and neurological patterns. Understanding these stages is crucial for appreciating the functions and disorders of sleep.

• Stage 1: Light sleep; brain powers down, producing theta waves (4-7 times per second). May experience hypnagogic images and myoclonic jerks.

• Stage 2: Brain slows further; heart rate and body temperature decrease, muscles relax, and eye movements cease. Accounts for about 65% of total sleep.

• Stages 3/4 (Deep, Slow Wave Sleep/SWS): Characterized by delta waves (1-2 cycles per second). Essential for feeling rested; sleepwalking may occur.

• Stage 5 (REM Sleep): Rapid Eye Movement sleep; associated with vivid dreaming and high brain activity similar to wakefulness.

Characteristics of REM Sleep

• Rapid eye movements

• Loss of muscle tone

• Low amplitude, high-frequency EEG

• Increased activity in many brain structures

• Autonomic nervous system activation

• Vivid dreaming

Why Do We Sleep?

• Recuperation Theories: Sleep restores homeostasis, energy levels, and repairs injuries.

• Adaptation Theories: Sleep serves as a protective mechanism and conserves energy.

Circadian Rhythms

Our sleep-wake cycle follows a roughly 24-hour rhythm, regulated by environmental cues (zeitgebers) and the biological clock in the suprachiasmatic nucleus (SCN) of the hypothalamus.

• Free running rhythm: Persists even without environmental cues.

Comparative Analysis of Sleep

• Sleep serves physiological functions in animals and humans.

• Sleep is not only for higher order human function; it is necessary for survival and health.

• There is a relationship between sleep length, body size, energy expenditure, and body temperature.

Sleep Loss and Deprivation

• Total sleep deprivation: Skipping an entire night's sleep.

• Chronic sleep restriction: Less sleep than normal or optimal.

• Chronic sleep disruption: Repeated disruptions of sleep length.

Consequences of insufficient sleep include impaired immune function, increased heart rate, hormone dysregulation, cognitive impairment, hallucinations, irritability, and inability to handle stress.

Sleep Restriction: Human Experiments

• Increased sleepiness and tendency to nap.

• Performance deficits on vigilance and cognitive tests.

• Amount of slow wave sleep increases after deprivation.

Sleep and Mortality

• Both short (<7 hours) and long (>9 hours) sleepers have higher mortality risk compared to those who sleep 7-8 hours.

Dreams and Dreaming

Why Do We Dream?

• Activation Synthesis Hypothesis: The brain tries to make sense of random neural activity during sleep.

• Virtual Trainer Hypothesis: Dreams may play a role in early development and simulation for prediction.

Neurocognitive Perspectives

• Dreams are shaped by the brain's default network and cognitive capacities.

• Dreams often reflect meaningful products of our experiences.

Freud's Dream Protection Theory

• Dreams act as guardians of sleep, disguising threatening wishes.

• Distinction between manifest content (actual dream) and latent content (hidden meaning).

Lucid Dreams

• Dreamer is aware they are dreaming and can influence the dream's course.

Sleep Disorders

• Hypersomnia: Excessive sleepiness (e.g., narcolepsy).

• Insomnia: Difficulty initiating or maintaining sleep.

• Sleep Apnea: Breathing stops during sleep.

• Restless Leg Syndrome: Uncomfortable sensations in legs.

• Sleepwalking/Night Terrors: Occur during deep sleep, often not remembered.

Altered States of Consciousness

Hallucinations

• Perceptual experiences without external stimuli; can occur in any sensory modality.

• May be caused by drugs, sensory deprivation, or medical conditions.

Out-of-Body and Near-Death Experiences

• OBEs: Sense of leaving one's body.

• NDEs: Experiences reported by people who nearly died.

Mystical Experiences

• Feelings of unity or oneness with the world, often with spiritual overtones.

• Psilocybin can increase frequency of mystical experiences.

Hypnosis

• Altered state involving imaginative suggestions and changes in consciousness.

• Induction process marks the beginning of hypnosis.

• People vary in their responsiveness to hypnotic suggestions.

Theories of Hypnosis

• Sociocognitive Theory: Role of beliefs, motivations, and expectations.

• Dissociation Theory: Hypnosis involves separation between personality functions.

Psychoactive Drugs and Consciousness

What is a Drug?

• No single precise definition; generally, a drug affects physiological functioning and is exogenous (originates outside the body).

Psychoactive Drugs

• Influence subjective experience and behavior by acting on the central nervous system (CNS).

Drug Administration and Absorption

• Ingestion: Easy, but unpredictable effects.

• Injection: Predictable effects, infection risk.

• Inhalation: Rapid effects, lung damage risk.

• Absorption: Through mucous membranes, can damage membranes.

Drug Metabolism and Elimination

• Drugs are metabolized by the liver and eliminated from the body.

• Some drugs cross the blood-brain barrier to affect the CNS.

Drug Tolerance and Sensitization

• Tolerance: Decreased effectiveness with repeated use.

• Sensitization: Increased responsiveness with repeated use.

Drug Withdrawal

• Adverse physiological reaction to sudden removal of a drug.

• Severity depends on type, duration, and speed of drug removal.

Classical Conditioning and Drug Tolerance

Drug tolerance can be learned through classical conditioning, where environmental cues become associated with drug effects.

Addiction

• Persistent use despite adverse effects.

• Models include moral, biomedical, psychological, and environmental.

Explanations for Drug Use and Abuse

• Sociocultural influences, genetic factors, and learning/expectancies all play roles.

Types of Psychoactive Drugs

• Depressants: Alcohol, sedatives; slow CNS activity.

• Stimulants: Nicotine, caffeine, cocaine, amphetamines; increase CNS activity.

• Opiates: Heroin, morphine, oxycontin; relieve pain, induce euphoria.

• Psychedelics: LSD, mescaline, PCP, Ecstasy; alter perception, mood, and thought.

• Marijuana: Contains THC; alters perception and mood.

Drug Effects and Withdrawal

• Short-term and long-term effects vary by drug and dose.

• Withdrawal symptoms can include headaches, fatigue, irritability, and more severe symptoms for drugs like opiates.

Summary Tables

Stages of Sleep

Stage	EEG Pattern	Main Features
Stage 1	Theta waves	Light sleep, hypnagogic images, myoclonic jerks
Stage 2	Sleep spindles, K-complexes	Heart rate slows, body temp drops, muscles relax
Stage 3/4	Delta waves	Deep sleep, sleepwalking, restorative
REM	Low amplitude, high frequency	Vivid dreams, rapid eye movement, muscle atonia

Major Drug Classes and Effects

Drug Class	Examples	Main Effects
Depressants	Alcohol, barbiturates	Relaxation, sleep induction, impaired coordination
Stimulants	Caffeine, nicotine, cocaine	Increased alertness, energy, heart rate
Opiates	Heroin, morphine	Pain relief, euphoria, risk of addiction
Psychedelics	LSD, PCP, Ecstasy	Altered perception, mood, thought
Marijuana	THC	Altered perception, relaxation, increased appetite

Key Equations

• EEG Frequency: $f = \text{cycles per second}$

Additional info:

• Some context and definitions have been expanded for clarity and completeness.

• Tables have been inferred and organized for study purposes.