2425 APPsych Modules 16 to 18 notes

Unit 2: Biological Bases of Behavior

Part II: States of Consciousness

Learning Targets

  • 16-1: Describe sleep as a state of consciousness.

  • 16-2: Describe how our biological rhythms influence our daily functioning.

  • 16-3: Describe the biological rhythm of our sleeping and dreaming stages.

  • 16-4: Explain how biology and environment interact in our sleep patterns.

  • 16-5: Describe sleep’s functions.

Circadian Rhythm

  • Definition: Biological clock that occurs on a 24-hour cycle, influencing sleep and wakefulness.

  • Impact: Affects sleep-wake cycles, temperature, hormonal, and digestive cycles.

  • Characteristics:

    • Body temperature rises before dawn, peaks during the day, dips in the afternoon, and drops again in the evening.

    • Optimally functioning cognitive processes occur at peak circadian arousal.

    • Age and experience can alter circadian rhythms.

Sleep

  • Definition: A periodic, natural loss of consciousness, distinct from unconsciousness due to coma or anesthesia.

  • Monitoring Sleep:

    • Electroencephalogram (EEG) records brain wave activity during sleep.

    • Different wave patterns occur at various sleep stages.

Stages of Sleep

1. NREM sleep

  • NREM-1: Transition phase characterized by hypnagogic sensations (e.g., feeling of falling).

  • NREM-2:

    • Lasts about 30 minutes.

    • Contains sleep spindles (bursts of rhythmic brain-wave activity) and K-complexes.

  • NREM-3 (Stages 3 & 4):

    • Deep sleep marked by delta waves (large-amplitude, slow brain waves).

    • Essential for physical restoration.

2. REM Sleep

  • Characteristics:

    • Rapid Eye Movements (REM) signal the start of vivid dreams.

    • Emotionally charged and story-like imagery.

    • Physiological arousal similar to when awake yet with near paralysis of muscles.

    • Accounts for 20-25% of sleep in an average night.

  • Function: Increases in REM occur after REM deprivation (REM rebound).

Sleep Cycle

  • The sleep cycle repeats approximately every 90 minutes, with younger adults cycling through 4-6 times per night.

  • Earlier cycles include more NREM-3; later ones focus on NREM-2 and REM sleep.

Sleep and Biological Influence

  • Suprachiasmatic Nucleus: A brain structure that regulates circadian rhythm by controlling melatonin release from the pineal gland based on light exposure.

  • Melatonin: A hormone that regulates sleep-wake cycles, affected by light cues.

Functions of Sleep

  • Protection: Keeps ancient humans safe during vulnerable hours.

  • Recuperation: Restores the immune system and facilitates neuronal repair.

  • Memory Consolidation: Helps reinforce memories and enhances creative thinking.

  • Growth Support: Releases human growth hormone during slow-wave sleep, essential for muscle development.

Learning Outcome 16-1: Sleep as a State of Consciousness

  • Recognition of sleep as a natural periodic loss of consciousness, distinct from more severe types of unconsciousness.

Learning Outcome 16-2: Biological Rhythms

  • Internal biological clocks synchronize bodily functions with a 24-hour cycle, with various physical and behavioral patterns dependent on circadian rhythms.

Learning Outcome 16-3: Biological Rhythm of Sleep Stages

  • Sleep progresses through distinct stages (NREM-1, NREM-2, NREM-3, and REM), cycling about every 90 minutes.

  • REM sleep features a paradoxical contrast of internal arousal and paralysis of the body.

Learning Outcome 16-4: Interaction of Biology and Environment

  • Biological systems (like circadian rhythms) mixed with cultural and individual factors influence sleep patterns.

Learning Outcome 16-5: Functions of Sleep

  • Sleep contributes to protection, restoration, memory consolidation, creative thinking support, and growth regulation.

Sleep Deprivation

  • Consequences:

    • Fatigue, impaired concentration, emotional irritability, depressed immune function, and heightened vulnerability.

Sleep Disorders

1. Insomnia

  • Persistent difficulty falling or staying asleep, affecting mental health and daily functioning.

  • Associated with anxiety and depression.

2. Narcolepsy

  • Sudden attacks of overwhelming sleepiness, leading to episodes of REM sleep, often triggered by strong emotions.

3. Sleep Apnea

  • Intermittent breathing interruptions during sleep, leading to extreme fatigue due to lack of deep sleep.

  • Treatment often involves a CPAP machine.

4. Somnambulism

  • Sleepwalking that typically occurs during NREM-3 sleep; more frequent in children.

5. REM Sleep Behavior Disorder

  • Characterized by physically acting out vivid dreams during REM sleep, leading to potential injury.

Dreams

  • Nature of Dreams: Sequences of thoughts and images varying from chaotic to structured.

  • Influences on dreams include daytime activities and emotional states.

Theories of Dreams

  • Wish Fulfillment (Freud): Dreams serve to satisfy unconscious wishes and manage conflicts.

  • Consolidation Theory: Dreams play a role in memory processing and emotional regulation during sleep.

  • Physiological Function Theory: Brain activity during REM sleep helps maintain neural pathways.

  • Cognitive Development Theory: Dreams reflect the dreamer's knowledge and cognitive development.

Substance Abuse Disorders

  • Definition: Continued craving and use of substances despite significant life consequences.

  • Tolerance: Diminished effects requiring increased intake for the same impact.

  • Addiction: A chronic condition leading to compulsive drug usage despite negative effects.

Categories of Psychoactive Drugs

  1. Depressants: Slow neural activity (e.g., alcohol, barbiturates, opiates).

  2. Stimulants: Excite neural activity (e.g., caffeine, nicotine, cocaine, methamphetamines).

  3. Hallucinogens: Distort perceptions (e.g., LSD, THC).

Learning Outcomes on Substances

  • Depressants: Slow functions; can impair memory and judgment.

  • Stimulants: Increase alertness and energy but can be highly addictive.

  • Hallucinogens: Alter perceptions, often evoking sensory images without actual input.