Module 1.5: Sleep Stages and Dream Theories

Module 1.5: Sleep

Sleep Stages and Dream Theories

Unit 1. Part 2

AP Psychology

Learning Objectives

  • Explain how the sleep/wake cycle affects behavior and mental processes throughout the day and night.

    • Consciousness

    • Circadian Rhythm

    • EEG Patterns and Sleep Stages

    • NREM vs. REM

    • Dream Theories

      • Activation-Synthesis

      • Consolidation

    • Sleep Theories

      • Memory consolidation

      • Restoration of depleted resources

    • Sleep Disorders

What is Consciousness?

  • Definition: Our subjective awareness of ourselves and our environment.

  • Types of Consciousness:

    • Spontaneous: not prompted by external cues/involuntarily 

      • Sleep

      • Daydreaming

      • "Flow"

    • Induced: intentional/significant change in awareness

      • Hallucinations

      • Hypnosis

      • Meditation

      • Psychoactive substances

Part 1: Sleep

  • Quote by Benjamin Franklin: "Early to bed and early to rise, makes a man healthy, wealthy, and wise."

  • Quote by Dr. William C. Dement: "We are not healthy unless our sleep is healthy, and we cannot make our sleep healthy unless we become thoroughly aware of both its peril and its promise."

  • Thomas Dekker: "Sleep is the golden chain that ties health and our bodies together."

What is Sleep?

  • A naturally occurring altered state of consciousness recognized by:

    • Reduced sensory activity

    • Muscle inhibition (reduction) 

    • Distinct brain activity differing from wakefulness

  • Stages of Sleep:

    • Non-REM (NREM): Stages 1-3

    • REM (Rapid Eye Movement): Fourth stage

  • Biological Clock: Sleep cycle is part of the biological clock, known as the Circadian Rhythm.

  • Importance of Sleep:

    • Restorative value (tissue growth, synaptic connections/pruning)

    • Memory consolidation (hippocampus converts experience to long-term memory)

    • Physical growth (hormones released during sleep)

Why Do We Sleep?

  • Sleep is crucial for mental and physical health:

    • Sleep to Remember

    • Remember to Sleep

Sleep Timing and Circadian Rhythm

  • Definition: The body's approximately 24-hour biological clock.

  • Regulates:

    • Sleep-wake cycle

    • Energy levels

    • Hunger

  • Key Processes:

    • “Endocrine homeostasis”: Hormones released to maintain balance

    • Natural light stimulates SCN (Suprachiasmatic Nucleus) located in hypothalamus

    • Pineal gland reduces melatonin secretion

    • Adrenal gland releases epinephrine to arouse the body

  • Disruptions:

    • Jet lag

    • Social jet lag

    • Shift work

Circadian Rhythm Patterns

  • Circadian Rhythm Overview:

    • Melatonin secretion follows a regular pattern throughout a 24-hour cycle.

    • Hormonal fluctuations include:

      • Highest melatonin secretion at 19:00

      • Body temperature drop by midnight

      • Blood pressure peak at ~6:45

      • Lowest body temperature at 04:30

      • Deepest sleep around 02:00

Chemicals Associated with Sleep

  • Key chemical:

    • Melatonin: Essential for regulating sleep cycles.

  • Other options (context required for effects):

    • A) Cortisol

    • B) Oxytocin

    • D) Testosterone

Sleep Stages

  • Sleep Cycle:

    • Cycle through 4 stages approximately every 90 minutes.

    • Recommended 7-9 hours of sleep yields about 5-6 cycles each night.

  • EEG (Electroencephalogram): Used to determine brain wave activity during different stages of sleep.

Sleep Stages Breakdown

  1. NREM Stage 1 (N1)

    • Duration: 5-10 minutes

    • Characteristics: Light sleep, alpha waves present.

  2. NREM Stage 2 (N2)

    • Duration: 10-20 minutes

    • Characteristics: Stable transitional stage, theta waves, harder to awaken.

  3. NREM Stage 3 (N3)

    • Characteristics: Deepest sleep, delta waves, hardest to awaken.

  4. REM Stage

    • Characteristics: Rapid eye movement, beta waves, internally active with externally paralyzed muscles, vivid dreams.

Characteristics of Sleep Stages

  • Stages cycle throughout the night:

    • NREM: Light NREM (Stage 1 & 2): Light sleep stages with brain activity aiding in memory.

    • Deep Sleep (Stage 3): Growth hormone released, essential for tissue repair.

    • REM Sleep: Essential for memory consolidation and emotional processing, often called paradoxical sleep due to muscle paralysis but active brain.

Dream Theories

  1. Activation-Synthesis Theory:

    • Suggests REM sleep triggers neural activity.

    • Neural networks weave random visual memories into narratives.

    • Implication: Dreams may hold no inherent meaning.

    • Criticism: Some dreams reflect aspects of the dreamer's life, challenging the idea that all dreams are meaningless.

  2. Information Processing/Consolidation Theory:

    • Function of dreams includes sorting daily events and memory consolidation.

    • Criticism: Involves dreaming about non-experienced events or past events.

Effects of Sleep Deprivation

  • Sleep deprivation can stem from irregular sleep patterns or sleep disorders.

  • Impacts encompass:

    • Short-term Effects: Acute attentional or mood problems.

    • Long-term Effects: Increased risk of physical illnesses.

Improving Sleep

  • Discussion on strategies to enhance sleep quality.

This structured study guide captures exhaustively the details presented in the transcript related to sleep, its stages, associated theories, impacts, and improvement advice.