Module 2 – Sleep and Dreaming (Summary Vocabulary)

30 vocabulary flashcards covering key terms, tools, sleep stages, brain waves and theories from Module 2: Sleep and Dreaming.

Normal Waking Consciousness (NWC)

A state of being awake, alert and fully aware of one’s thoughts, feelings and surroundings.

Altered States of Consciousness (ASC)

Any condition of awareness that differs noticeably from NWC, such as sleep, hypnosis or drug-induced states.

Sleep

A naturally recurring altered state of consciousness marked by reduced awareness, responsiveness and movement.

Sleep–Wake Cycle

The 24-hour pattern of alternating sleep and wakefulness governed by circadian rhythms.

Circadian Rhythms

Biological processes that follow a roughly 24-hour cycle, e.g., sleep–wake and body temperature fluctuations.

Suprachiasmatic Nucleus (SCN)

A cluster of cells in the hypothalamus that acts as the body’s master biological clock, regulating circadian rhythms.

Melatonin

A hormone released by the pineal gland in darkness that promotes sleepiness.

Ultradian Rhythms

Biological cycles shorter than 24 hours, such as the roughly 90-minute sleep cycle.

Sleep Cycle

A full progression through NREM and REM stages, lasting about 90 minutes and repeating several times a night.

NREM Stage 1 (NREM 1)

Light sleep with theta waves and slow eye movements; easy to awaken.

NREM Stage 2 (NREM 2)

Light sleep featuring sleep spindles and K-complexes on the EEG.

NREM Stage 3 (NREM 3)

Deep sleep dominated by delta waves; critical for physical repair and growth.

REM Sleep

Sleep stage with vivid dreams, rapid eye movements, high brain activity and muscle paralysis.

Electroencephalograph (EEG)

Device that records electrical activity of the brain to identify sleep stages.

Electromyograph (EMG)

Instrument that measures muscle activity or tone during sleep.

Electrooculograph (EOG)

Device that records eye movements, useful for detecting REM sleep.

Beta Waves

Fast, low-amplitude brain waves associated with alert, waking consciousness.

Alpha Waves

Slightly slower waves linked to relaxed, drowsy wakefulness.

Theta Waves

Medium-amplitude waves typical of light sleep (Stages 1 and 2).

Delta Waves

Slow, high-amplitude waves characteristic of deep NREM 3 sleep.

Dreams

Sequences of images, emotions and thoughts occurring mainly during REM sleep.

Freud’s Dream Theory

Proposes that dreams express unconscious wishes and desires.

Activation–Synthesis Theory

Suggests the brain creates a story to make sense of random neural signals during sleep.

Information-Processing Theory

Posits that dreaming helps consolidate memories and solve problems.

Threat Simulation Theory

Claims dreams allow the brain to rehearse responses to perceived dangers.

Sleep Hygiene

Daily habits and environmental factors aimed at promoting good-quality sleep.

Healthy Sleep Hygiene Practices

Behaviours such as a regular bedtime, a cool dark room, limited caffeine and a relaxing routine that aid sleep.

Poor Sleep Hygiene Practices

Habits like inconsistent bedtimes, screen use in bed and late heavy meals that disrupt sleep.

Sleep Deprivation

The condition of not obtaining enough or good-quality sleep, leading to impaired cognition, mood and health.

Delayed Sleep Phase

A biological shift—common in adolescents—where the internal clock causes later sleep and wake times.

alpha waves

medium frequency low amplitude

beta waves

high frequency low amplitude

theta waves

medium aplitude and medium amplitude

delta waves

low frequency high amplitude waves associated with deep sleep.