Lecture 7: Consciousness – Wakefulness, Sleep, and Drugs

Consciousness

Definition and Dimensions

Consciousness refers to a person's subjective awareness, including thoughts, experiences, and self-awareness. It exists on a continuum from full alertness to deep unconsciousness.

• Content of consciousness: The richness and complexity of mental experiences.

• Level of consciousness: The degree of wakefulness or arousal.

Examples of states: REM sleep, deep sleep, light sleep, drowsiness, conscious wakefulness, mind wandering, hypnosis, vegetative state, coma, general anesthesia, locked-in syndrome.

Wakefulness & Sleep

Biological Rhythms

Biological rhythms are regular fluctuations in physiological processes. They are classified by their duration:

• Circannual rhythms: Last longer than a day (e.g., annual migration in animals).

• Ultradian rhythms: Shorter than a day (e.g., heart rate, urination).

• Circadian rhythms: Approximately 24 hours (e.g., sleep-wake cycle, hunger, concentration).

The circadian rhythm is regulated by the following pathway:

• Light (retina) → Suprachiasmatic nucleus (SCN) (in hypothalamus) → Pineal gland (releases melatonin)

Exogenous rhythms are influenced by external cues (e.g., light), while endogenous rhythms are generated internally.

How Much Sleep is Needed?

Sleep requirements vary by age and individual factors. For college students, 7-9 hours per night is recommended.

• Consequences of sleep deprivation: Increased risk of cardiovascular disease, stress, mental health issues, impaired exercise performance, and poor academic outcomes.

• Influencing factors: Stress, use of smartphones, caffeine, energy drinks.

• Chronotype: Tendency to prefer sleeping earlier ("morningness") or later ("eveningness"). Chronotype changes with age.

Stages of Sleep

Sleep is divided into several stages, each characterized by distinct brain wave patterns:

• Awake: Beta waves (alert), alpha waves (relaxed).

• Stage 1: Transition to sleep; theta waves.

• Stage 2: Light sleep; sleep spindles and K-complexes appear.

• Stages 3 & 4: Deep sleep; delta waves dominate.

• REM sleep: Rapid eye movement, "paradoxical sleep" (brain active, body paralyzed), vivid dreams.

Sleep cycle: The stages repeat in cycles of about 90 minutes throughout the night.

Theories of Sleep

• Restoration/Repair Hypothesis: Sleep allows the body and brain to repair and "cleanse" themselves (e.g., removal of metabolic waste).

• Preservation/Protect Hypothesis: Sleep evolved to protect organisms during periods of vulnerability.

• Special adaptations: Some animals (e.g., dolphins) exhibit unihemispheric sleep (one brain hemisphere sleeps at a time).

Dreams

Dreams occur most vividly during REM sleep. Several theories explain their purpose:

• Psychoanalytic Approach (Freud): Dreams reflect unconscious desires and conflicts. Manifest content is the literal storyline; latent content is the hidden psychological meaning.

• Problem-Solving Theory (Cartwright): Dreams help process and solve problems from waking life.

• Activation-Synthesis Hypothesis (Hobson & McCarley): Dreams result from the brain's attempt to make sense of random neural activity during sleep.

Drugs and Consciousness

Pharmacology and Psychoactive Drugs

Pharmacology is the study of how drugs influence the nervous system and behavior. Psychoactive drugs are substances that alter mood, thought, or behavior by affecting neurotransmission.

• Administration: Drugs can be taken orally, inhaled, injected, etc.

• Mechanisms: Drugs may increase or decrease neurotransmitter activity.

• Tolerance: Decreased response to a drug after repeated use. Can be metabolic (body processes drug faster) or cellular (neurons adapt, e.g., down-regulation of receptors).

• Dependence: Can be physical (withdrawal symptoms) or psychological (craving, compulsive use).

Major Classes of Psychoactive Drugs

• Stimulants: Increase CNS activity (e.g., caffeine, nicotine, amphetamines, cocaine).

• Depressants: Decrease CNS activity (e.g., alcohol, benzodiazepines).

• Opioids: Relieve pain, produce euphoria (e.g., morphine, heroin, codeine).

• Hallucinogens: Alter perception (e.g., LSD, psilocybin).

• Cannabis: Has both depressant and hallucinogenic properties (e.g., THC in marijuana).

Examples and Mechanisms

• Caffeine: Adenosine antagonist; increases alertness.

• Nicotine: Stimulates acetylcholine receptors; increases arousal.

• Alcohol: Enhances GABAergic activity; depresses CNS.

• Amphetamines: Increase dopamine and norepinephrine release; used to treat ADHD.

• Cocaine: Blocks dopamine reuptake; powerful stimulant.

• Opioids: Bind to opioid receptors; include natural (morphine, codeine) and synthetic (heroin, fentanyl) forms.

• Cannabis: Contains THC; acts on cannabinoid receptors (CB1, CB2).

Drug Tolerance and Dependence

• Tolerance: Repeated use leads to reduced effect; higher doses needed for same effect.

• Dependence: Physical (withdrawal symptoms) and psychological (craving, compulsive use).

Table: Major Classes of Psychoactive Drugs

Class	Examples	Main Effects	Mechanism
Stimulants	Caffeine, Nicotine, Cocaine, Amphetamines	Increased alertness, energy	Increase neurotransmitter activity (dopamine, norepinephrine)
Depressants	Alcohol, Benzodiazepines	Relaxation, drowsiness	Enhance GABAergic activity
Opioids	Morphine, Heroin, Codeine	Pain relief, euphoria	Bind to opioid receptors
Hallucinogens	LSD, Psilocybin	Altered perception	Serotonin receptor agonists
Cannabis	THC (marijuana)	Relaxation, altered perception	CB1/CB2 receptor agonist

Additional info:

• Sleep disorders (e.g., insomnia, sleep apnea, narcolepsy, night terrors, sleepwalking) are important clinical topics but were only briefly referenced in the original notes.

• For further study, see: "Circadian Rhythms and Sleep" (Ch. 5), "Drugs and Behavior" (Ch. 5/6) in standard psychology textbooks.