Sleep & Dreaming (Dreams)

Vocabulary flashcards covering key concepts from Sleep & Dreaming module.

Normal waking consciousness (NWC)

State of wakefulness with awareness of the external world and one’s own sensations and existence at any given moment.

Altered states of consciousness (ASC)

States distinctly different from normal waking consciousness in terms of awareness and experience; can be naturally occurring or deliberately induced.

Circadian rhythm

A biological 24-hour cycle regulating sleep-wake patterns and other processes, influenced by light and dark cues.

Ultradian rhythm

Biological rhythms that occur more than once per day; for example, blinking, heartbeat

Suprachiasmatic nucleus (SCN)

Part of the hypothalamus that regulates circadian rhythms in response to light information from the eyes.

Pineal gland

Gland that secretes melatonin to promote sleep, regulated by the SCN.

Melatonin

Hormone that increases sleepiness in darkness and decreases with light exposure.

Sleep-wake cycle

The cycle of sleeping and waking influenced by circadian rhythm and homeostatic factors.

NREM sleep

Non-REM sleep; comprises stages 1–3, with increasing depth and characteristic EEG patterns (spindles and K-complexes in stage 2; delta waves in stage 3).

REM sleep

Rapid eye movement sleep; high brain activity, muscle atonia, rapid eye movements, and vivid dreams often occur.

EEG

Electroencephalograph; records electrical activity and brainwave patterns.

EMG

Electromyograph; measures muscle activity; low activity during REM sleep due to atonia.

EOG

Electro-oculograph; records eye movements; high activity during REM sleep.

Sleep hygiene

Healthy habits, behaviours, and environmental factors that promote good-quality, consistent sleep.

Sleep deprivation

Lack of sufficient sleep or poor sleep quality, leading to impaired functioning.

Insomnia

Difficulty falling asleep or staying asleep.

Chronotype

Individual preference for times of day when a person is most awake and alert, influenced by genetics and circadian rhythms.

Dreams

Mental experiences during sleep; content often tied to REM sleep and may reflect emotion, memory, or daily experiences.

Threat-stimulation theory

Theory that dreaming helps practice responses to real-life threats, improving survival; REM-related immobility supports a freeze response.

Memory consolidation

Process by which short-term memories are solidified into long-term memories, aided by sleep and dreaming.

Saw-tooth waves

A high-frequency, low-amplitude brainwave pattern associated with REM sleep and dreaming.

Sleep cycle duration

Approximately 90 minutes per cycle, with 4–5 cycles per typical night.

Stage 1 EEG patterns

Transition between wakefulness and sleep; presence of alpha waves (relaxed wakefulness) and theta waves (early sleep) as alpha fades.

Stage 2 features

Longest sleep stage; theta activity with sleep spindles (bursts linked to memory) and K-complexes (arousal suppression).

Stage 3 features

Deep sleep; presence of theta and delta waves (low-frequency, high-amplitude).

REM dream recall

REM sleep is when dreaming is most likely to be remembered.

Light exposure and melatonin

Light suppresses melatonin production while darkness increases it, helping regulate sleep onset and quality.

high amplitude

more asleep

high frequency

more awake

sleep spindles

memory consolidation

k complex

brain trying to suppress arousal

delta wave

high amplitude and low frequency

theta waves

higher amplitude and lower frequency than alpha

alpha waves

moderate amplitude and frequency

beta waves

high frequency and low amplitude (brain is active)

babies and toddlers sleep hours

12+ hours

children and adolescants

9-10 hours

adults

7-8 hours

elderly

6-7 hours

sleep

a naturally occuring altered state of consciousness that happens every 24 hours

different altered states

induced or naturally occuring

when there is more light..

less melatonin is produced

rem sleep percentage

20%

sleep cycle duration

90 minutes