Chapter 4 Sleep States of Consciousness

Consciousness

Awareness of internal stimuli (pain, hunger, thoughts) and external stimuli (light, sounds).

Biological Rhythms

Internal, recurring patterns of biological activity (e.g., body temperature fluctuations, menstrual cycles).

Circadian Rhythm

Biological rhythm taking place over approximately $24\,\text{hours}$ (e.g., sleep-wake cycle).

Homeostasis

Tendency to maintain optimal balance within a biological system.

Suprachiasmatic Nucleus (SCN)

Biological clock in the hypothalamus synchronized by light signals from the retina.

Melatonin

Hormone secreted by the pineal gland that regulates sleep; stimulated by darkness, inhibited by light.

Chronotype

Individual differences in circadian patterns (e.g., morning larks vs. night owls).

Sleep Debt

Chronic insufficiency of sleep leading to decreased alertness, memory impairments, and physiological stress.

Sleep Rebound

Phenomenon where a sleep-deprived individual falls asleep faster during subsequent sleep opportunities.

Melatonin

Regulates sleep-wake cycle and immune function.

Follicle-Stimulating Hormone (FSH)

Regulates the reproductive system.

Luteinizing Hormone (LH)

Regulates the reproductive system.

Growth Hormone

Plays a role in physical growth, maturation, and metabolism.

Adaptive / Evolutionary Theories

Theories that suggest sleep restores energy and evolved as a defense mechanism against predation.

Cognitive Function Theories

Theories proposing that sleep is essential for memory consolidation, language learning, and emotional processing.

NREM (Non-REM) Sleep

Sleep stages characterized by varying levels of brain activity, including alpha and delta waves.

Stage 1 Sleep

Transitional phase with alpha waves ($8-12\,\text{Hz}$) shifting to lower-frequency theta waves ($4-7\,\text{Hz}$).

Stage 2 Sleep

Deep relaxation; features sleep spindles and K-complexes.

Stage 3 Sleep

Deep sleep characterized by low-frequency, high-amplitude delta waves ($< 3\,\text{Hz}$).

REM (Rapid Eye Movement) Sleep

Sleep stage characterized by brain activity resembling wakefulness, rapid eye movement, and vivid dreams.

REM Rebound

Increased proportion of REM sleep following sleep deprivation.

Dream Theories

Theories that attempt to explain the purpose and meaning of dreams.

Freud's Dream Theory

Distinction between manifest content (actual storyline) and latent content (hidden psychological meaning).

Somnambulism (Sleepwalking)

Complex behaviors during slow-wave NREM sleep.

REM Sleep Behavior Disorder (RBD)

Failure of normal REM muscle paralysis leading to physical acting out of dreams.

Restless Leg Syndrome

Uncomfortable leg sensations relieved by movement.

Night Terrors

Sudden panic and arousal during NREM sleep without memory of the event.

Sleep Apnea

Repeated cessation of breathing during sleep, treated with CPAP devices.

Sudden Infant Death Syndrome (SIDS)

Unexpected infant death during sleep, mitigated by safe sleeping practices.

Narcolepsy

Inability to resist sleep during waking hours, often accompanied by cataplexy and hallucinations.

Substance Use Disorder

Compulsive drug use despite significant adverse consequences.

Physical Dependence

Involves physical withdrawal symptoms upon drug cessation.

Psychological Dependence

Emotional need or drug craving to relieve distress.

Tolerance

Need for increased drug doses to achieve previously experienced effects.

Agonist

Facilitates neurotransmitter system activity.

Antagonist

Impedes or blocks neurotransmitter activity.

Depressants

GABA agonists that suppress CNS activity (e.g., alcohol, barbiturates).

Stimulants

Increase neural activity via dopamine and other neurotransmitter systems (e.g., cocaine, nicotine).

Opioids

Analgesics mimicking endogenous endorphins (e.g., heroin, morphine).

Hallucinogens

Alter sensory and perceptual experiences via serotonin systems (e.g., LSD, cannabis).

Hypnosis

State of extreme self-focus and heightened suggestibility.

Dissociation Theory

Hypnosis represents a divided stream of consciousness.

Social-Cognitive Theory

Hypnotized individuals are fulfilling social role expectations.

Meditation

Mindful practice of focusing attention to clear the mind and achieve relaxed awareness.