Overview Sleep and Psychoactive Drugs

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Varying Levels of Consciousness (sleep/wakefulness)

The idea that our awareness of ourselves and our environment shifts

Circadian Rhythm

A roughly 24-hour biological cycle that regulates sleep–wake patterns

Stages of Sleep

Sleep cycles through NREM (1–3) and REM sleep in 90-minute cycles. Each stage has distinct physiological and brain-wave characteristics.

NREM-1

Light sleep; easy to wake. Characterized by theta waves and may include fleeting hallucinations.

NREM-2

Deeper light sleep; characterized by sleep spindles (rapid bursts of activity) and K-complexes. Most sleep time is spent here.

NREM-3

Deep sleep / slow-wave sleep with delta waves. Hard to wake; growth hormone released; important for restorative processes.

Hypnagogic Sensations

Strange, dreamlike experiences during the transition into sleep (NREM-1), like falling, floating, hearing a voice, or jerking awake.

REM (Paradoxical Sleep)

A sleep stage where the brain is active (like wakefulness) but the body is paralyzed. Heart rate and breathing increase. Most vivid dreaming occurs here.

Dreaming and REM

REM sleep is the stage most strongly associated with rich, story-like dreams due to heightened cortical activity.

REM Rebound

If a person is deprived of REM sleep, they will enter REM more quickly and spend more time in REM during the next sleep period.

Activation–Synthesis Theory (Dreams)

A theory stating that dreams are the brain’s attempt to make sense of random neural activity originating from the brainstem during REM sleep.

Consolidation Theory (Dreams)

The idea that dreams reflect the brain’s effort to process and store memories, reinforce learning, and integrate new information.

Why We Sleep: Memory Consolidation and Restoration

• Consolidate memories and improve learning

• Restore the brain and body (growth hormone release, tissue repair)

• Remove metabolic waste (via glymphatic system)

• Maintain emotional regulation and immune function

Insomnia

Persistent difficulty falling asleep, staying asleep, or getting restorative sleep.

Narcolepsy

A disorder characterized by sudden, uncontrollable sleep attacks and often cataplexy (loss of muscle tone). Caused by loss of hypocretin/orexin-producing neurons.

REM Sleep Behavior Disorder (RBD)

A disorder where the normal paralysis of REM sleep is absent, causing a person to physically act out dreams.

Sleep Apnea

Repeated cessation of breathing during sleep, causing brief awakenings. Leads to fatigue and cardiovascular risks.

Somnambulism (Sleepwalking)

Walking or performing complex behaviors during NREM-3 sleep. The person typically has no memory of the event.

Adequate sleep is linked to

• Better immune function

• Emotional stability

• Physical recovery

• Cognitive performance
  Sleep deprivation increases risks of obesity, accidents, depression, and impaired memory.

Naps

Short daytime sleep episodes.

20–30 min naps

boosts alertness

90 min naps

full sleep cycle; helpful for creativity/memory

Microsleep

Very brief (1–10 second) involuntary episodes of sleep, typically caused by severe sleep deprivation. Dangerous when driving.

Manifest Content (Freud)

The literal storyline of the dream.

Latent Content (Freud)

The hidden, symbolic meaning that reflects unconscious wishes or conflicts.

Lucid Dreaming

A dream in which the sleeper becomes aware they are dreaming and may sometimes control the dream’s content or actions.

Agonist

A substance that mimics or enhances the action of a neurotransmitter by binding to its receptor and activating it.
Example: Morphine is an agonist for endorphin receptors.

Antagonist

A substance that blocks or inhibits a neurotransmitter by binding to its receptor without activating it.

Reuptake Inhibitors

Drugs that block the reabsorption (reuptake) of neurotransmitters back into the presynaptic neuron, causing more neurotransmitter to remain in the synapse.
Example: SSRIs keep serotonin in the synapse longer.

Psychoactive Drugs

Chemical substances that alter perceptions, mood, thinking, or behavior by affecting neurotransmitter systems in the brain.

Stimulants

Drugs that increase neural activity, heighten alertness, and boost energy.

• Caffeine: Blocks adenosine, increasing wakefulness.

• Cocaine: Blocks dopamine reuptake, causing a dopamine buildup → euphoria

Depressants

Drugs that slow down central nervous system activity, reducing inhibition, reaction time, and self-control.

Alcohol

Enhances GABA (inhibitory neurotransmitter) and reduces glutamate.

Hallucinogens

Drugs that distort perception, alter sensory experiences, and may trigger hallucinations.

Marijuana (THC)

Binds to cannabinoid receptors,affecting perception, memory, and mood.

Opioids

Drugs that reduce pain and create intense feelings of euphoria by acting as agonists for endorphin receptors.
Highly addictive due to strong dopamine release in reward pathways.

Tolerance

A reduced response to a drug after repeated use, requiring larger doses to achieve the same effect.

Physical dependence

Body relies on the drug; withdrawal occurs without it.

Psychological dependence

Emotional or mental craving for the drug.

Addiction

Compulsive drug use despite negative consequences; driven by reward pathways in the brain.

Withdrawal Symptoms

Unpleasant physical or psychological effects that occur when a drug is discontinued.

Symptoms vary by drug but can include anxiety

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