Consciousness, Sleep Stages, and Dream Theories in Psychology

Consciousness

Our awareness of internal and external sensations. It involves both conscious content (subjective experiences) and states of consciousness (arousal and attention).

Split-Brain

A condition where the corpus callosum is severed. Studies on these patients show how different brain hemispheres have specialized functions and how consciousness is a product of the brain's physical workings.

Attention

The process of selecting information to prioritize for processing.

Inattentional Blindness

A failure to see perfectly visible objects when our attention is focused on another task.

Sleep

An altered state of consciousness where the brain is highly active. We cycle through distinct stages multiple times a night in the general pattern 1-2-3-2-REM.

Awake

Beta waves (high frequency, low amplitude) when alert and engaged. Alpha waves (more rhythmic, higher amplitude) when relaxed and drowsy.

Stage 1 (NREM)

The transition to sleep, characterized by theta waves. This stage is very light and lasts only a few minutes.

Stage 2 (NREM)

Deeper sleep characterized by theta waves along with Sleep Spindles and K-Complexes.

Sleep Spindles

Brief bursts of high-frequency waves (12-14 Hz) that may play a role in memory consolidation.

K-Complexes

Large, high-amplitude waves that occur about once a minute and can be triggered by unexpected noises.

Stage 3 (SWS - Slow-Wave Sleep)

The deepest stage of sleep, with slow (less than 4 Hz), high-amplitude delta waves. The body is very relaxed, and it is difficult to wake someone. Nightmares often occur during this stage.

REM (Rapid Eye Movement) Sleep

A stage where the brain is highly active with desynchronized beta-like waves. It is characterized by rapid eye movements, high physiological arousal, and muscle paralysis (atonia). This is when vivid, narrative-based dreams occur.

Freud's Psychoanalytic Theory

Believed dreams represent unconscious desires, distinguishing between manifest content (the actual story) and latent content (the hidden meaning).

Activation-Synthesis Hypothesis

Suggests dreams are the brain's attempt to make sense of random neural firing that occurs during REM sleep.

Evolutionary/Threat Simulation Theory

Argues that dreams may have a biological purpose, allowing us to rehearse survival strategies.