03-05-25+sleep+CANVAS

Exam Information

• Date: 5 March 2025

• Test 2: Covers Chapters 3 & 4, including all in-class and Canvas content since Test 1.

Psychoactive Drugs and Consciousness

• Psychoactive Drugs: Chemicals that alter perceptions, mood, consciousness, cognition, or behavior by affecting neural transmission.

  • Examples:

    • Birds & Fermented Pyracantha

    • Cats & Catnip

    • Most commonly used drug: Caffeine

Types of Psychoactive Drugs

• Depressants: Reduce neural activity and slow body functions.

  • Examples: sedatives, tranquilizers, barbiturates, opiates, alcohol.

• Stimulants: Excite neural activity and speed up bodily functions.

  • Most common: caffeine and nicotine.

• Opioids: Reduce the experience of pain and increase pleasure.

Addiction

• Addiction: Compulsive drug craving and use despite negative consequences.

• Tolerance: Increased need to take larger doses to achieve effects; tolerance reductions during rehabilitation can be fatal.

• Brain Adaptation: Positive correlation; the brain adapts to the presence of drugs.

Dependence

• Types of Dependence: Physical and psychological.

  • Physical dependency leads to tolerance and withdrawal symptoms when not using the drug.

  • Psychological dependence: Cravings and distress (e.g., depression, anxiety).

Withdrawal

• Withdrawal Effects: Physical and psychological symptoms occur upon discontinuing use of an addictive drug.

  • Common symptoms: anxiety, tension, cravings, physical effects (nausea, fever, aches).

Sleep: Biological Rhythms

• Circadian Rhythm: A 24-hour cycle of varying alertness, body temperature, and growth hormone secretion.

  • Light inhibits melatonin secretion from the pineal gland. Melatonin increases when light decreases, regulating the circadian clock.

Disruption of Circadian Rhythms

• Causes of Disruption:

  • Long flights

  • Artificial light

• Evolutionarily, humans had little light at night. High light levels at night can disrupt sleep by confusing the eyes.

Stages of Sleep

• 4 Distinct Stages: Approximately every 90 minutes of sleep.

  • Brain activity can be measured by EEG.

• Stage 1: Transition to sleep.

• Stage 2: Light sleep characterized by brain wave spindles preventing thalamus from processing sensory information.

• Stages 3/4: Slow-wave sleep (deep sleep); minimal eye movement and muscle activity, making it hard to wake.

  • Associated with bedwetting, night terrors, and sleepwalking.

REM Sleep

• Characteristics of REM Sleep:

  • Periods last about 10 minutes.

  • Rapid eye movement, increased heart rate, irregular breathing, and muscular paralysis.

  • Dreaming occurs; the frontal cortex is deactivated while other brain areas are active.

  • REM sleep is essential for memory and brain development.

Functions of REM Sleep

• Although still not entirely understood, REM sleep appears crucial for:

  • Memory consolidation.

  • Stimulation of brain development.

  • Babies spend about 50% of their sleep in REM sleep.

  • REM Rebound: Occurs if REM sleep is deprived, leading to intense and peculiar dreams during recovery sleep.

The Nature of Dreams

• Freud's Perspective: Dreams fulfill unconscious desires; includes manifest and latent content.

• Activation-Synthesis Hypothesis: Dreams result from random neural firing interpreted by the mind.

Nightly Sleep Cycles

• As the night progresses, more time is spent in REM and less in deep sleep.

• Older adults typically cycle through sleep stages more rapidly.

Reasons for Sleep

• Restorative Theory: Sleep repairs the body and brain.

  • Growth hormone is released during deep sleep; essential for immune system restoration.

• Circadian Rhythm Theory: Sleep is adaptive; keeps animals safe during dangerous times and conserves energy when food is not available.

• Learning Facilitation: Sleep strengthens neural connections, consolidates memory, and enhances creative thinking.

Effects of Sleep Deprivation

• Consequences include:

  • Decreased cognitive function (attention and memory).

  • Increased reaction times, fatigue, and weight gain.

  • Heightened risk of depression and irritability.

  • Compromised immune system; may shorten lifespan.

Common Sleep Disorders

• Insomnia: Difficulty in falling or staying asleep.

• Sleeping pills and alcohol can reduce REM sleep.

• Sleep Apnea: Pauses in breathing during sleep.

• Sleepwalking: Engaging in activities while still asleep.

• Narcolepsy: Excessive daytime sleepiness and unexpected sleep attacks.

• REM Behavior Disorder: Acting out dreams during REM sleep.