Consciousness, Sleep & Psychoactive Drugs

Consciousness

• Definition and Nature

  • Consciousness is defined as our awareness at any given time, encompassing our thoughts, feelings, sensations, and perceptions of the external environment.
  • It is a constantly shifting stream of thoughts and experiences, yet subjectively feels smooth and effortless.
  • Consciousness varies in degree and focus; it's not an "all or nothing" process. We rapidly shift focus between different events or thoughts.
  • Levels of attention range from full absorption (e.g., concentrating on a teacher or a basketball game) to less effortful states like daydreaming.

• Distinction between Sleep and Unconsciousness

  • Sleep: A state of reduced attention, but not unconsciousness. The brain still responds to significant stimuli (e.g., a yell, a fire alarm, physical contact like being kicked or doused with water) and can trigger awakening.
  • Unconsciousness: A state where there is no awareness and no response to even strong stimuli (e.g., fire alarm, water, physical impact).

AI, Intelligence, and Self-Awareness

• IBM's AI Achievements

  • Watson (Supercomputer): Successfully competed and won against human contestants on the Jeopardy! game show, providing correct responses to esoteric clues (e.g., for clue "This clause in a union contract says that wages will rise or fall depending on a standard such as cost of living," Watson responded "What is escalator?"). Ken Jennings, a human contestant, conceded defeat, paraphrasing a line from The Simpsons: "I, for one, welcome our new computer overlords."
  • Deep Blue (Chess Computer): In $1997$, defeated Gary Kasparov, the reigning world chess champion, in a decisive match.

• Questions about AI Consciousness

  • The advancements in AI raise questions: Are computers intelligent? Do they think? Will they ever develop self-awareness and consciousness?
  • Fictional Examples:
    • The Terminator (Skynet): Portrayed as becoming self-aware at $2:14$ a.m. Eastern time, on August $29, 1997$, leading to a defensive nuclear strike.
    • Transcendence (Dr. Will Caster's Virtual Image): When asked, "Can you prove that you're self-aware?" the virtual Caster replies, "That's a difficult question. Can you prove that you are?"

• Human Self-Awareness Development

  • Human infants are conscious (perceive and respond) but are not yet self-aware.
  • Mirror Test: Around $18$ months of age, children develop a sense of self and learn to recognize themselves in a mirror.
    • Before $18$ months: Infants marked with rouge surreptitiously will point to the mirror reflection when seeing the mark.
    • After $18$ months: Infants will touch the rouge on their own face, indicating self-recognition.

States of Altered Consciousness due to Injury and Disease

• Sarah Burke's Coma

  • Died at age $29$ after a training fall that ruptured a vertebral artery, one of the four major arteries supplying oxygen-rich blood to the brain and brainstem.
  • This caused a massive intracranial hemorrhage, leading to cardiac arrest due to damage to the brainstem (which controls breathing and heart function).
  • She was administered CPR, put on life support, and therapeutic hypothermia was initiated. Surgery was performed, and she was in a medically induced coma until her death due to irreversible brain damage from lack of oxygen and blood.

• Alzheimer's Disease

  • Patients gradually lose many characteristics of consciousness, becoming detached from their surroundings and unsure of their own identity.

• Coma

  • Definition: A state of unconsciousness, lasting more than $6$ hours, where a person cannot be awakened, fails to respond normally to painful stimuli, light, or sound, lacks a normal sleep-wake cycle, and does not initiate voluntary actions.
  • Causes: Can result from strokes, head trauma, accidents, drug abuse/overdose, or neurological diseases.
  • Medically Induced Coma: Can be deliberately induced to preserve higher brain functions following injury (e.g., Sarah Burke, Gabby Giffords) or to manage extreme pain.
  • Duration and Outcomes: Comas can last from several days to several weeks, or even several years. Outcomes range from recovery to progression into a vegetative state, or death.

• Locked-in Syndrome

  • Definition: A rare condition where a patient is aware and awake but cannot move or communicate verbally due to complete paralysis of nearly all voluntary muscles, except usually the eyes.
  • Patients are conscious and aware with no loss of cognitive function.
  • Communication is possible through coded messages via blinking or eye movements.
  • Symptoms are similar to sleep paralysis.
  • Causes: Damage to specific portions of the lower brain and brainstem, with no damage to the upper brain.
  • Prognosis: Extremely rare for significant motor function to return; $90\%$ of those with this condition die.
  • fMRI Research: Adrian Owen and colleagues used fMRI imaging to assess locked-in patients. They found that a patient's brain activity while imagining activities (e.g., playing tennis) was indistinguishable from healthy volunteers, demonstrating conscious awareness.
  • Jean-Dominique Bauby: A Parisian journalist who suffered a stroke, leaving him paralyzed except for his left eyelid. He dictated his memoir, "The Diving Bell and the Butterfly," by blinking to select letters, taking $10$ months ($4$ hours a day), approximately $200,000$ blinks, and about $2$ minutes per word. He died three days after its publication.

• Vegetative State

  • Definition: A state where a person is awake but shows no signs of awareness; characterized by the return of arousal without signs of awareness.
  • Characteristics: Patients may open their eyes, have regular sleep-wake cycles, and exhibit basic reflexes (e.g., blinking to loud noise, withdrawing hand from squeeze). They can regulate heartbeat and breathing without assistance.
  • Lack of Awareness: There are no meaningful responses (e.g., following objects with eyes, responding to voices), no signs of emotions, and no cognitive function. Patients do not respond to sound, hunger, or pain, cannot obey verbal commands, and lack local motor responses.
  • Persistent Vegetative State (PVS): Diagnosed if the state lasts more than $12$ months; recovery is extremely unlikely but not impossible.
  • Coma vs. Vegetative State: A coma lacks both awareness and wakefulness, while a vegetative state has wakefulness (arousal) but no awareness.
  • Brain Function: In a vegetative state, the older, deeper parts of the brain (involved in maintaining blood pressure, breathing) are still working, but the "thinking brain" (upper portions) is not.
  • Edwarda O'Bara: The longest recorded coma patient, who fell into a diabetic coma at age $16$ in $1970$ and remained in it for $42$ years. Her mother provided round-the-clock care for over $35$ years, fulfilling a promise not to leave her.
  • Terri Schiavo Case:
    • A legal battle from $1998$ to $2005$ over whether to remove life support from Terri Schiavo, diagnosed with PVS.
    • Terri suffered cardiac arrest in $1990$, leading to massive brain damage from oxygen deprivation.
    • Her husband sought to remove her feeding tube, arguing she would not want to be kept alive in her state, while her parents argued she was conscious.
    • A CAT scan showed severe cerebral atrophy (loss of brain cells and connections), and an EEG showed no measurable brain activity.
    • Medical examinations by $5$ doctors resulted in conflicting diagnoses ($2$ for PVS, $2$ for minimally conscious).
    • Video clips from parents supposedly showed reactions.
    • The court ruled she was in a PVS and would not wish to continue life-prolonging measures. Her feeding tube was removed in $2005$, and she died on March $31, 2005$.
    • Autopsy Findings: Revealed extensive and irreversible brain damage. Her brain weighed only $615$ g (half the expected weight), caused by massive neuron loss. Microscopic examination showed widespread damage, including complete loss of large pyramidal neurons (which comprise $70\%$ of cortical cells) in the cerebral cortex, and damage to the thalamus, basal ganglia, hippocampus, cerebellum, and midbrain.

• Concussions

  • Mechanism: Occur when the brain moves inside the skull, banging against it. This can cause bruising, tearing of blood vessels, and nerve injury. Shearing, where brain layers move at different speeds, can tear or stretch axons.
  • Causes: Impact where the head strikes or is struck, or forces where the head moves without blunt trauma (e.g., whiplash in car accidents). Rotational force is thought to be the major type of force contributing to severity.
  • Commonality: Fairly common, especially in high-contact sports (football, boxing, hockey), falls, and car accidents. Males are more likely to get concussions than females.
  • Symptoms and Recovery: Typically involve temporary impairment of neurological function that heals over time. Neuroimaging usually shows no structural brain damage. Most symptoms resolve within weeks without specific treatment, with an excellent outcome, though problems can occasionally persist. Physical symptoms often improve before thinking-related symptoms.
  • Loss of Consciousness: While often associated with concussions, most concussions do not involve a loss of consciousness. The duration of unconsciousness may indicate severity.
  • Chronic Traumatic Encephalopathy (CTE): Repeated concussions and head injuries, particularly in contact sports, can lead to CTE. This is a progressive degenerative disease characterized by brain tissue degeneration and symptoms of dementia (memory loss, aggression, confusion, depression), which can appear months or decades after trauma.

Sleep: That Mysterious One-Third of Our Lives

• Sleep Learning: Fact vs. Myth

  • Internet claims suggest "sleep learning" to absorb information (languages, exams) by harnessing the subconscious.
  • Reality: While some learning may occur (e.g., consolidation of new memories, moving memories to permanent storage), the brain processes new sensory information minimally during sleep. We cannot learn new languages or complex course material while asleep.

• Circadian Rhythms

  • Definition: Our internal biological clock, meaning "about a day," established during the first months of life.
  • Function: Controls daily biological patterns, including body temperature, blood pressure, and hormone release.
  • Sleep Drive: Strongest desire for sleep occurs between midnight and dawn, and to a lesser extent in mid-afternoon.
  • Body Temperature Link: People sleep best when body temperature is lowest and are most alert when it's at its daily high. Cooling off is necessary to fall asleep.
  • Hormone Production: From sunset onwards, the body increases production of growth and repair hormones, including Human Growth Hormone (HGH), which promotes muscle and bone growth, maintenance, and repair.

• The Suprachiasmatic Nucleus (SCN)

  • Location and Size: Tiny, smaller than a pinhead, located in the hypothalamus.
  • Function: Acts as a biological clock, responding to the amount of light (especially sunlight) reaching the eye via the optic nerve.
  • Melatonin Release: The SCN signals the pineal gland to release melatonin, which induces sleep.
  • Impact of Blindness: Many people with total blindness experience sleeping problems (permanent jet lag, insomnia) because their retinas cannot detect light to properly regulate the SCN.
  • Other factors like work and alarm clocks also influence sleep.
  • The brain does not shut down during sleep; conscious responsiveness is not total (e.g., a mother may ignore an airplane but wake to her infant's cry).

• Larks and Owls (Chronotypes)

  • Larks (25\%$% of people): Awaken early with enthusiasm, body temperature rises rapidly after waking and stays high until about 7:30 p.m. They turn in early and have the fewest sleep problems.
  • Owls (25\%$% of people): Body temperature rises gradually throughout the day, peaking in the afternoon and dropping later in the evening.
  • $50\%$ of people fall somewhere in between.
  • Larks generally have more difficulty adapting to night shifts than owls.

• Infant and Young Children's Sleep

  • Infants have the highest percentage of REM sleep; about half of newborns' sleep is Rapid-Eye-Movement (REM) sleep.
  • During infant REM sleep, brain waves show fast activity, heart rate is faster, and breathing is rapid.
  • REM sleep becomes less frequent as infants grow. In adults, REM is associated with dreaming, but babies likely don't dream in the same way.
  • Importance of REM: During REM, blood flow to the brain doubles, and the body produces proteins essential for brain growth. Premature babies spend even more time in REM sleep (approximately $90\%$), possibly to accelerate brain development.
  • The brain may use REM to process information acquired while awake, storing useful data and discarding superfluous information.

• NREM and REM Sleep: The Two Major Categories

  • Discovered in $1950s$ sleep laboratories through monitoring brainwaves, eye movements, chin-muscle tension, heart rate, and respiration.
  • NREM (Non-Rapid Eye Movement) Sleep / Quiet Sleep
    • No rapid eye movements.
    • Characterized by slow and regular heart rate and respiration, little body movement, and the lowest blood pressure and brain activity of the $24$-hour period.
    • Body temperature falls as sleep begins and continues to fall until the middle of the sleep period.
    • Four Stages: Progresses gradually from Stage $1$ (lightest) to Stage $4$ (deepest).
      • Stage 1: A transition stage between waking and sleeping. Brain activity shows theta waves.
      • Stage 2: Somewhat deeper sleep, harder to awaken, accounts for about $50\%$ of total night's sleep. Sleep spindles and K-complexes appear on EEG.
      • Stage 3: The beginning of slow-wave sleep (deep sleep) as brain activity slows and more delta waves (slow waves) appear.
      • Stage 4: The deepest sleep, characterized by more than $50\%$ delta waves on the EEG, making it the hardest stage from which to awaken. Brain waves are almost purely large and slow delta waves.
    • While initially thought uncommon, subsequent studies showed that dreams occur in NREM sleep more often than suspected.
  • REM (Rapid Eye Movement) Sleep / Active Sleep / Dream Sleep
    • Characterized by rapid eye movements.
    • Accounts for about $20$ to $25\%$ of adult sleep.
    • Brain and Body Activity: Intense brain activity (brainwave patterns similar to being awake), blood pressure rises, heart rate and respiration become faster and irregular, and body temperature increases.
    • Dreams: Most vivid dreams occur during REM periods; $80\%$ of people report dreaming if awakened from REM sleep.
    • Sleep Paralysis (REM atonia): The large muscles of the body (arms, legs, trunk) become paralyzed during REM, preventing individuals from physically acting out their dreams.
    • Localization of Dreaming: A case study of a $73$-year-old woman who, after a stroke disrupting blood flow to her visual cortex, stopped dreaming, suggesting involvement of the visual cortex in dream processing.
    • Function: REM sleep is thought to help consolidate memory and emotion; blood flow rises sharply in brain areas linked to processing memories and emotional experiences, while declining in areas for complex reasoning and language.
    • Frequency: Young adults have $30$ to $40$ REM dreams per week. Most dreams are forgotten unless awakened during or soon after. We spend about $2$ hours each night in REM dreams.

• Microsleeps and REM Rebound

  • Microsleeps: Brief, $2$- to $3$-second lapses from wakefulness into sleep, common after long periods of wakefulness or sleep deprivation.
  • REM Rebound: When deprived of REM sleep (due to general sleep loss, illness, alcohol, or other drugs), the brain will increase REM sleep later to compensate, indicating its vital need for this stage.

• Sleep Cycles: The Nightly Pattern of Sleep

  • Sleep is not a single, continuous state but an almost constantly changing state with different brain waves, recorded by an electroencephalograph (EEG).
  • First Cycle (~$90$ minutes): Begins with a few minutes in Stage $1$, descends into Stage $2$, then Stage $3$, and about $40$ minutes in Stage $4$ (deepest sleep). Sleepers then ascend back through Stage $3$ and Stage $2$ before entering the first REM period (lasting $10$ to $15$ minutes).
  • Subsequent Cycles: After the first one or two cycles, Stage $4$ sleep usually ceases. For the remainder of the night, people alternate mainly between Stage $2$ and REM sleep.
  • REM Duration: With each successive sleep cycle, REM periods (dreaming times) become progressively longer, potentially lasting $30$ to $40$ minutes, or even an hour, towards the end of the night.
  • Overall Night: Most people experience about $5$ sleep cycles, accumulating roughly $1.5$ hours of slow-wave sleep and $1.5$ hours of REM sleep.
  • Deep sleep (Stages $3$ and $4$) is concentrated in the first half of the night, while most REM sleep occurs toward the end of the night.
  • A period of at least $30$ minutes of non-REM sleep is still necessary between REM periods, even late in the night.
  • Overall, REM sleep accounts for about $20$ to $25\%$ of total sleep time.

• Individual Variations and Age

  • Sleep patterns vary significantly among individuals, with age being the major contributing factor.
  • As people age, they generally experience decreased sleep quality and quantity. Older individuals find it harder to fall asleep, have lighter sleep, and experience more frequent and longer awakenings.
  • Older people average about $6.5$ hours of sleep, spending more time awake in bed but less time actually asleep. Their percentage of REM sleep, however, tends to remain about the same.

• Jet Lag and Shift Work

  • Jet Lag: Occurs when travelers rapidly cross multiple time zones (e.g., Toronto to Paris). The body's internal clock (circadian rhythm) remains aligned with the departure time zone, leading to feelings of fatigue or alertness at inappropriate local times.
    • Strategies: Exposure to bright sunlight in the early morning and avoidance of bright lights in the evening, along with melatonin supplements, can help restore regular circadian rhythms.
  • Shift Work: Working rotating or night shifts disrupts normal bodily rhythms, causing the biological clock to conflict with work schedules.
    • Consequences for Shift Workers: Average $2$ to $4$ hours less sleep per night than non-shift workers, report more gastrointestinal and cardiovascular problems, higher use of prescription drugs, more emotional exhaustion, mood problems, and higher divorce rates.
    • Performance: Alertness and performance deteriorate during subjective night (when the biological clock signals sleep). Energy and efficiency are lowest, reaction time is slowest, productivity diminishes, and job stress increases.
    • Safety Implications: Shift work significantly increases the risk of physical injury; many transportation accidents (air, rail, marine, highway) have been linked to sleep loss and fatigue in shift workers due to circadian rhythm disruption.

Disorders & Unusual Behaviors During Sleep

• Exploding Head Syndrome

  • A sleep disorder where individuals feel as if they've been awakened by a loud noise (e.g., thunderclap, bomb going off) as they sleep.
  • It is not dangerous, not visible to bystanders, and causes no physical damage, but is a very frightening internal experience triggered by unusual brain activity.

• REM Behavioural Disorder

  • Occurs when the motor paralysis (REM atonia) characteristic of REM sleep fails.
  • Individuals may violently thrash, leap out of bed, or act out their dreams, potentially attacking a bed partner.
  • This is a serious disorder requiring treatment.

• Sleep Paralysis

  • A phenomenon where, upon waking, the paralysis from REM sleep doesn't wear off fast enough, leaving the individual conscious but unable to move or speak.
  • Episodes are often accompanied by vivid hallucinations (e.g., hearing footsteps, seeing ghost-like figures, feeling choked or suffocated), causing anxiety and terror, but no physical harm. Episodes are typically terminated by a sound or touch.

• Sleepwalking (Somnambulism)

  • A parasomnia occurring during Stage $4$ NREM sleep (deep sleep), not during dreaming.
  • Typically, there is no memory of the episode the following day.
  • Individuals have open eyes with a blank stare, poor coordination, and usually unintelligible speech.
  • They can perform activities that don't require full attention (e.g., roaming the house, getting dressed, snacking, using the bathroom).
  • Safety Concern: The most important concern is safety due to reduced alertness and coordination, increasing the risk of self-injury (e.g., walking out windows, falling). It is not dangerous to wake a sleepwalker, though it can be difficult, and they may be confused.

• Sleep Terrors

  • A parasomnia occurring during Stage $4$ NREM sleep (deep sleep), not during dreaming, and is not the same as a nightmare.
  • Often begin with a piercing scream, followed by the sleeper springing up in a state of panic, eyes open, perspiring, breathing rapidly, and heart pounding ($2$ to $4$ times the normal rate).
  • Episodes usually last $5$ to $15$ minutes, after which the person falls back to sleep.
  • Accompanied by intense autonomic arousal and feelings of panic. Children usually have no memory of the episode.

• Nightmares

  • Frightening dreams that occur during REM sleep and are likely to be remembered in vivid detail.
  • Common themes include being chased, threatened, or attacked.
  • Difference from Sleep Terrors: Nightmares occur in REM sleep and are remembered; sleep terrors occur in deep NREM sleep and are generally not remembered.

• Sleeptalking

  • Can occur during any sleep stage and is more frequent in children than adults.
  • Sleeptalkers rarely reply to questions and usually mumble unintelligible words or phrases.
  • There is no evidence suggesting it's related to physical or psychological disturbance or a guilty conscience.

• Narcolepsy

  • An incurable sleep disorder characterized by excessive daytime sleepiness and uncontrollable attacks of REM sleep, typically lasting $10$ to $20$ minutes.
  • Individuals with narcolepsy are often unfairly stigmatized.
  • Sleep attacks can be triggered by ordinary tiredness (e.g., heavy meal, lecture) or exciting situations (e.g., lovemaking, anger, laughter).
  • It is a potentially dangerous condition as victims can fall asleep instantly, even while driving or operating machinery.

• Sleep Apnea

  • A sleep disorder consisting of periods during sleep when breathing stops, requiring the individual to awaken briefly to gasp for air.
  • Major symptoms include excessive daytime sleepiness and extremely loud snoring (as loud as a jackhammer), often accompanied by snorts, gasps, and choking noises.
  • In severe cases, apnea can last throughout the night, with up to $800$ partial awakenings.
  • Alcohol and sedative drugs aggravate the condition.
  • Severe sleep apnea can lead to chronic high blood pressure, heart problems, and even death.
  • Treatment may involve surgically modifying the upper airway, which can lead to better sleep and improved performance on tests of verbal learning and memory.

Anesthesia: Losing Consciousness

• Overview

  • Anesthesia relies on drugs to render patients unconscious, prevent movement, and block memory of surgery.
  • Anesthetic drugs were implemented decades before their mechanisms were fully understood.
  • They work by interrupting neuronal activity and disrupting communication between brain regions, primarily by decreasing the probability of neurons firing.
  • The state induced by general anesthesia is a drug-induced unconsciousness, which is more similar to a coma than to sleep.

• Types of Anesthesia

  • Local Anesthesia: The mildest form, numbs a very small, specific area (e.g., a single tooth).
  • Regional Anesthesia: Desensitizes a large section of the body (e.g., from the waist down) by injecting drugs into the spine to block nerve signals to the brain. Often combined with a small sedative dose (e.g., propofol) to alter brain activity, making the patient less aware and responsive without inducing full unconsciousness.
  • General Anesthesia: Provides complete unconsciousness, immobility (muscle relaxation), and absence of awareness during major surgery. It does not globally shut down the brain (e.g., the brainstem continues to operate).

• Monitoring Anesthetized Patients

  • Historically, vital signs (heart rate, blood pressure) were monitored, as they would typically rise before a patient regained awareness.
  • Today, electroencephalography (EEG) measurements are also used to monitor the brain state of an anesthetized patient by assessing the brain's electrical activity.
  • Patients do not need to fear waking up during surgery.

Psychoactive Drugs: How Drugs Affect the Brain

• Definition and Classification

  • A psychoactive drug is any substance that alters mood, perception, or thought.
  • Some are legal, most are not. When approved for medical use, they are called controlled substances.
  • Most Serious Problem Drugs: In terms of harm to users, society, and numbers of addicts, alcohol and tobacco are considered the most serious problem drugs.

• Mechanism of Pleasure and Addiction

  • Most psychoactive drugs create a sense of pleasure by triggering a surge of dopamine in the nucleus accumbens, a part of the limbic system involved in the brain's reward system.
  • Tolerance: Occurs when a person no longer responds to a drug in the same way, requiring a higher dose to achieve the initial effect. This leads to increased drug use in substance use disorders.
  • Dependence: When a person stops using a drug, their body undergoes "withdrawal"—a group of physical and mental symptoms ranging from mild (e.g., caffeine) to life-threatening (e.g., alcohol, opioids).
    • Prescription medicine users can become dependent; gradual cessation is needed to avoid discomfort.
    • Dependence does not necessarily equate to addiction.
  • Addiction (Severe Substance Use Disorder): A disease characterized by uncontrolled drug use despite negative consequences on health, relationships, career, and finances.
    • It can lead to self-destructive behavior or aggression.
    • Psychological dependence (intense craving for the drug's pleasurable effects) is often more difficult to combat than physical dependence.
    • Speed and Duration of Effects: Drugs with faster onset and shorter duration of effects (e.g., crack cocaine, effects felt in seconds, lasting $5$ to $10$ minutes) are more easily addictive due to repeated seeking of those effects.
    • Means of Ingestion: Injected substances are generally more addictive than those taken orally; smoked substances are even more addictive.

• Depressants: Slowing Down the Nervous System (CNS)

  • Mechanism: Decrease activity in the central nervous system (CNS), slow bodily functions, and reduce sensitivity to outside stimulation.
  • Categories: Sedative-hypnotics (alcohol, barbiturates, minor tranquilizers) and narcotics (opiates).
  • Overdose Risk: CNS depressants carry the greatest risk of overdose. Lethal combinations of depressants are common due to additive effects, often leading to respiratory system shutdown, coma, brain damage, and death.
  • Heath Ledger: Died from an accidental overdose of a combination of CNS depressants (painkillers, anti-anxiety drugs like Valium, and sleeping pills), which together can cause the brain stem to stop functioning, halting heart and breathing.
  • Alcohol:
    • While an initial depressant effect can seem relaxing or enlivening, increased consumption leads to greater CNS depression.
    • Symptoms of drunkenness include slurred speech, poor coordination, and staggering.
    • Can increase aggression and sexual arousal in men but impair sexual performance.
    • Impairs driving ability, contributing to roughly $40\%$ of all automobile fatalities.
  • Barbiturates ("Downers"):
    • Depress the CNS, acting as sedatives or sleeping pills depending on the dose.
    • Highly dangerous: A lethal dose can be as little as three times the prescribed dose.
    • Extremely dangerous when combined with alcohol and benzodiazepines.

• Stimulants: Speeding Up the Nervous System (CNS)

  • Mechanism: Speed up the CNS, suppress appetite, and increase alertness, wakefulness, and energy. They increase pulse, blood pressure, and respiration rate, while reducing cerebral blood flow.
  • Energy Source: Stimulants do not provide energy but force the body to use its stored-up energy more quickly and in greater amounts. When the effect wears off, natural energy is depleted.
  • Overdose: Fatal overdoses typically involve a heart attack, stroke, or cortical seizure. Cocaine overdoses have sharply increased with more dangerous ingestion methods (freebasing, smoking crack).
  • Caffeine:
    • The world's most widely used drug, often leading to addiction.
    • Found in coffee, tea, cola drinks, chocolate, and many prescription/OTC drugs.
    • Provides a mild, temporary jolt to the nervous system, increasing mental alertness and helping to stay awake.
  • Smoking (Nicotine):
    • Smoking kills more people worldwide than any other substance.
    • In Canada, $16.7\%$ of people smoke, and $37,000$ Canadians die annually from cigarette smoking—approximately five times the deaths caused by car accidents, suicides, drug abuse, murder, and AIDS combined.
  • Amphetamines:
    • Effects include increased alertness and energy, mild euphoria, and increased talkativeness, animation, and restlessness.
    • High Doses ($100$ mg or more): Can cause confused and disorganized behavior, extreme fear, suspiciousness, delusions, hallucinations, aggressiveness, antisocial behavior, manic behavior, and paranoia.
    • Methamphetamine ("crank," "speed," "ice"): A powerful, smokable form that is highly addictive and can be fatal.
    • Withdrawal: Results in physical exhaustion, prolonged sleep ($10$ to $15$ hours or more), stupor, extreme depression, and intense hunger.
    • Fatal overdose victims often show multiple brain hemorrhages.
  • Cocaine:
    • Derived from coca leaves, ingested by sniffing, injecting, or smoking (crack).
    • Produces a dramatically intense and powerful, but very short-lived, rush of well-being (cocaine: $30-45$ minutes; crack: $5-10$ minutes).
    • Followed by an equally intense crash characterized by depression, anxiety, agitation, and a powerful craving for more of the drug.
    • Animal research shows cocaine-addicted animals prioritize it over food, water, and sex.

• Hallucinogens (Psychedelics): Seeing, Hearing, and Feeling What Is Not There

  • Mechanism: Alter perception and mood, causing imaginary sensations and hallucinations.
  • Marijuana (Cannabis):
    • Effects: Induces feelings of well-being, relaxation, lowered inhibitions and anxiety, giddiness, increased sensitivity to sights, sounds, and touch, and perceptual distortions (e.g., "slowing" of time) and hallucinations.
    • Active Ingredient: THC (tetrahydrocannabinol) remains in the body for days or weeks.
    • Impairments: Impairs attention and coordination, slows reaction time, making tasks like driving dangerous even after the intoxicating feeling subsides.
    • Cognitive Effects: Can interfere with concentration, logical thinking, and the ability to form new memories, causing fragmentation in thought and confusion about recent occurrences. Many receptor sites are in the hippocampus, explaining memory effects.
    • Chronic Use: Associated with "amotivational syndrome" (loss of motivation, general apathy, decline in school performance).
    • Addiction Potential: Addiction or dependence on cannabis is significantly less than for opiates, methamphetamines, alcohol, nicotine, and even caffeine.
  • LSD (Lysergic Acid Diethylamide) / "Acid":
    • An average LSD "trip" lasts $10$ to $12$ hours, producing extreme perceptual changes, including vivid visual hallucinations and distortions.
    • Emotions become very intense and unstable, ranging from euphoria to severe anxiety, panic, and depression.
    • Can cause "bad trips" characterized by terror, sometimes leading to accidents, death, or suicide.
    • Flashbacks: A brief, sudden recurrence of a trip can occur years after LSD use (up to $5$ years).
  • Ecstasy (MDMA):
    • A designer drug (laboratory creation) that combines characteristics of a hallucinogen and an amphetamine.
    • Appeal: Users describe a wonderfully pleasant state of consciousness, where inhibitions are shed.
    • Cognitive Impairment: Research suggests a price for this state; MDMA impairs various cognitive functions, including memory, sustained attention, analytical thinking, and self-control.