1.12 Variations in Consciousness

Sleep and its stages

Consciousness is our awareness of ourselves and our environment, and it varies across states like waking, sleep, and hypnosis. Sleep cycles through stages measured by EEG: NREM stages 1-3 (light to deep sleep, with stage 3 showing slow delta waves) and REM sleep, marked by rapid eye movement, vivid dreaming, and muscle paralysis (REM paralysis). A full cycle repeats about every 90 minutes, with REM increasing later in the night.

Sleep theories and disorders

Theories explain why we sleep: circadian rhythm regulation (via the hypothalamus's suprachiasmatic nucleus), restoration of the body/brain, and memory consolidation. Disruptions include insomnia (trouble sleeping), narcolepsy (sudden sleep attacks/REM intrusion), sleep apnea (breathing stops), and night terrors/somnambulism (sleepwalking, occurring in NREM sleep).

Dreams, hypnosis, and drugs

Dream theories include Freud's wish-fulfillment (manifest vs. latent content) and the activation-synthesis hypothesis (brain interprets random neural firing). Hypnosis is a state of focused attention and heightened suggestibility. Psychoactive drugs alter consciousness: depressants (alcohol) slow activity, stimulants (caffeine, cocaine) speed it up, and hallucinogens (LSD) distort perception; repeated use can cause tolerance, dependence, and withdrawal.

Key terms

REM sleep

Sleep stage with rapid eye movement, vivid dreams, and temporary muscle paralysis.

Circadian rhythm

The roughly 24-hour biological cycle regulating sleep-wake patterns, controlled by the suprachiasmatic nucleus.

Activation-synthesis hypothesis

Theory that dreams arise from the brain synthesizing meaning from random neural activity during sleep.

Narcolepsy

A sleep disorder causing sudden, uncontrollable sleep attacks and intrusions of REM sleep.

Tolerance vs. withdrawal

Tolerance: needing more of a drug for the same effect. Withdrawal: negative symptoms when stopping drug use.

Try an AP-style question

What best explains this?

1. Automatic processing
2. Selective hypnosis
3. Retrograde amnesia
4. REM intrusion