Chapter 4 – Consciousness, Sleep, and Drugs (Psychology 2e, OpenStax)

Consciousness: Core Concepts

• Consciousness – active awareness of both internal states (e.g., hunger, pain, thoughts) and external stimuli (e.g., light, sound).
• Wakefulness – condition of high sensory awareness, rapid thought, and purposeful behavior.
• Sleep – natural, cyclical period of reduced awareness and low physical activity; historically described as a “quiet and mysterious pause” in daily life (e.g., Anker’s 1895 painting of two sleeping girls).

Biological & Circadian Rhythms

• Biological rhythm – internal, repeating cycle of bodily activity such as:
  • Body-temperature fluctuation.
  • Menstrual cycle.
  • Daily variations in alertness.
• Circadian rhythm (≈ 24\;\text{hours}):
  • Governed by the suprachiasmatic nucleus (SCN) in the hypothalamus.
  • Synchronizes with environmental light–dark cues.
• Homeostatic control via the hypothalamus maintains biological balance (homeostasis).
• Typical body-temperature pattern: gradual rise across the day, peak in afternoon, drop overnight to an early-morning low.

SCN, Melatonin, & Chronotype

• SCN – densely packed cluster of neurons above the optic chiasm; receives direct retinal input, letting daylight reset the “master clock.”
• Melatonin (pineal-gland hormone):
  • Secretion triggered by darkness → promotes sleepiness.
  • Daylight inhibits release.
• Sleep regulation – brain mechanisms toggling sleep ↔ wake and aligning the cycle with the external world.
• Chronotype – individual, trait-like circadian activity pattern (e.g., “lark” vs. “owl”).

Disruptions of Normal Sleep

• Jet lag: internal clock ≠ external time → fatigue, irritability, insomnia.
• Rotating shift work: changing work hours impede circadian entrainment → chronic exhaustion, sleep troubles, possible depression/anxiety.
• Bright-light therapy: intense artificial light used to phase-shift or stabilize circadian timing (useful for night-shift workers or seasonal affective issues).

Sleep Deprivation

• Sleep debt: cumulative effect of repeated sleep loss.
• Sleep rebound: faster sleep onset during later opportunities after deprivation.
• Documented consequences span cognition (attention, memory), mood, immune function, metabolic health, & accident risk.

Recommended Daily Sleep Durations

(Abridged from NSF chart)

• Newborns (0–3 mo): 14–17\,h ideal.
• School-age (6–13 yr): 9–11\,h ideal; <$7\,h$ not advised.
• Adults (18–64 yr): 7–9\,h optimal; <$6\,h$ linked to impairment.
• Older adults (≥65 yr): 7–8\,h recommended.

What Is Sleep? Neurobiology & Hormones

• Definition: state of low activity + diminished awareness.
• Key brain sites:
  • Thalamus & hypothalamus → slow-wave (NREM) regulation.
  • Pons → REM initiation.
• Hormones secreted/regulated during sleep:
  • Melatonin, follicle-stimulating hormone, luteinizing hormone, growth hormone.
• Polysomnography (PSG) combines EEG, EOG, EMG, ECG, etc., to profile sleep stages.

Why Do We Sleep?

• Adaptive (evolutionary) hypotheses:
  1. Energy restoration.
  2. Safety from nocturnal predators.
     (Empirical support limited.)
• Cognitive function hypothesis:
  • Sleep, particularly slow-wave sleep (SWS), crucial for memory consolidation, learning, and executive function.
• Additional benefits: weight regulation, stress reduction, mood stability, motor coordination.

EEG Brain Waves

• Alpha: low-frequency, high-amplitude, synchronized; relaxed wakefulness.
• Theta: low-freq, low-amp; light sleep.
• Delta: very low-freq, high-amp; deep SWS.

Stages of Sleep

1. Stage 1 (N1)
   • Transition from wake → sleep; alpha waves.
   • Respiration & HR slow, muscle tension & core temperature drop.
2. Stage 2 (N2)
   • Theta waves dominant.
   • Key markers: sleep spindles (rapid 12–14 Hz bursts) & K-complexes (single high-amp waves) → memory & sensory gating roles.
     3–4. Stages 3 & 4 (N3/SWS)
   • Delta waves.
   • Further slowed respiration/HR; hardest to awaken.
3. REM Sleep
   • Rapid eye movements, atonia of voluntary muscles, vivid dreaming.
   • EEG resembles wakefulness (beta-like activity).

• Hypnogram: visual timeline showing ~90-min cycles of NREM→REM repeated 4–6× per night, with longer REM episodes toward morning.

Dreams: Theories & Types

• Freud: dreams = “royal road” to unconscious.
  • Manifest content (literal storyline).
  • Latent content (hidden meaning).
• Jung: access to collective unconscious; dreams contain universal archetypes.
• Contemporary research: dreams often reflect salient life events; may create a protoconscious virtual reality aiding waking cognition.
• Lucid dreaming: dreamer gains awareness & partial control within dream state.

Sleep Disorders

Insomnia

• Trouble initiating/maintaining sleep ≥3 nights/week for ≥1 month.
• Risk factors: age, drugs, mood disorders, poor sleep hygiene.
• Interventions: stimulus control, CBT-I, relaxation training.

Parasomnias

• Sleep-walking (somnambulism): during SWS.
• REM sleep behavior disorder (RBD): REM atonia absent → vigorous acting out of dreams; treated with clonazepam.
• Restless-leg syndrome (RLS): uncomfortable leg sensations relieved by movement.
• Night terrors: panic screams, autonomic arousal during NREM; little recall.

Sleep Apnea

• Breathing stops 10–20\,s repeatedly; severe fatigue.
  1. Obstructive: airway collapse.
  2. Central: CNS fails to trigger breaths.
• CPAP device = standard therapy.

SIDS (Sudden Infant Death Syndrome)

• Unexplained infant death during sleep (<12 mo; higher in boys).
• Risk factors: prematurity, household smoking, overheating.
• “Safe to Sleep” campaign promotes supine sleeping, firm mattress, no loose bedding.

Narcolepsy

• Irresistible daytime sleep attacks; often with cataplexy & hypnagogic hallucinations.
• Triggered by strong emotions/stress.
• Treated with psychostimulants (e.g., modafinil, amphetamine).

Substance-Use & Psychoactive Drugs

• Substance use disorder (DSM-5): compulsive use despite harm; involves
  • Physiological dependence (tolerance, withdrawal).
  • Psychological dependence (cravings, emotional need).
• Tolerance: escalating dose needed for prior effect.
• Withdrawal: adverse symptoms upon cessation.

Major Drug Classes & Mechanisms

1. Depressants (sedative-hypnotics)

   • Examples: alcohol, barbiturates, benzodiazepines.
   • GABA agonists: open Cl⁻ channels → neuronal hyperpolarization → CNS suppression.
   • Effects: slowed reaction, impaired judgment, possible respiratory depression & coma at high doses.

2. Stimulants

   • Examples: cocaine, amphetamines, cathinones, MDMA, nicotine, caffeine.
   • Dopamine (or adenosine/acetylcholine) mechanisms:
     • Cocaine/amphetamines block dopamine reuptake → excess synaptic DA.
     • Nicotine agonizes nicotinic ACh receptors; caffeine antagonizes adenosine receptors.
   • Effects: increased HR/BP/temp, euphoria, appetite suppression; high doses → paranoia, hallucinations.

3. Opioids (Opiates)

   • Heroin, morphine, fentanyl, codeine, methadone.
   • Bind μ-opioid receptors → analgesia, euphoria, severe addiction risk; overdose via respiratory depression.

4. Hallucinogens / Psychedelics

   • LSD & mescaline (serotonin 5-HT₂A agonists), PCP & ketamine (NMDA antagonists), cannabis (CB₁/CB₂ agonist + mild hallucinogenic properties).
   • Produce perceptual distortions, synesthesia, time alteration; physiological responses vary (↑HR/BP common early on).

GABA & Dopamine Synapse Diagrams (Conceptual)

• GABA-A receptor with sites for alcohol/barbiturate/benzodiazepine → Cl⁻ influx → neuronal inhibition.
• Dopamine synapse: cocaine/amphetamine block DA transporter → higher extracellular DA.

Altered States Beyond Drugs

Hypnosis

• Intense self-focus + susceptibility to suggestion.
• Myths debunked: person remains in control; cannot be forced into actions against will.
• Clinical uses: pain control, anxiety/depression treatment, habit cessation (smoking, weight).

Meditation

• Sustained attention on breath, mantra, or present sensations.
• Induces relaxed but alert consciousness.
• Empirical benefits: stress reduction, improved sleep quality, pain management, mood & anxiety improvement.