OpenStax Psychology Chapter 4: Sleep and Dreaming

Consciousness

Awareness of internal and external stimuli, like hunger, pain, or light.

Wakefulness

A state characterized by high levels of sensory awareness, thought, and behavior.

Biological rhythm

An internal cycle of biological activity, such as body temperature fluctuations.

Circadian rhythm

A biological rhythm that occurs over approximately 24 hours.

Suprachiasmatic nucleus (SCN)

The brain's clock mechanism located in the hypothalamus, synchronized by light.

Homeostasis

The tendency of a biological system to maintain an optimal balance.

Melatonin

A hormone stimulated by darkness that induces sleepiness, released by the pineal gland.

Sleep regulation

The brain's control of switching between sleep and wakefulness.

Chronotype

An individual's personal circadian pattern of activity and alertness.

Jet lag

Mismatch between internal circadian cycles and the external environment.

Rotating shift work

Work schedules changing from early to late, disrupting circadian rhythms.

Sleep debt

The cumulative result of chronic insufficient sleep.

Sleep rebound

Falling asleep faster during subsequent opportunities after sleep deprivation.

Brain areas controlling sleep

Thalamus and hypothalamus (slow-wave sleep), and the pons (REM sleep).

Adaptive function of sleep

Evolutionary theory that sleep restores resources and avoids nocturnal predatory risks.

Cognitive function of sleep

The theory that sleep is essential for memory formation and cognitive processing.

Alpha waves

Relatively low frequency, high amplitude, synchronized brainwaves of early relaxation.

Theta waves

Low frequency, low amplitude brainwaves characteristic of Stage 2 sleep.

Delta waves

Low frequency, high amplitude, desynchronized brainwaves of deep Stage 3 sleep.

Stage 1 Non-REM sleep

Transitional phase between wakefulness and sleep with slowed respiration and alpha waves.

Sleep spindles

Rapid bursts of high frequency brainwaves during Stage 2 sleep.

K-complexes

Very high amplitude patterns of brain activity during Stage 2 sleep.

Stage 3 Non-REM sleep

Deep slow-wave sleep characterized by delta waves and slowed heart rate.

REM sleep

Sleep stage with rapid eye movements, dreaming, and voluntary muscle paralysis.

Hypnogram

A diagram illustrating the stages of sleep as they occur over time.

Manifest content

The actual, literal storyline and imagery of a dream.

Latent content

The hidden, psychological meaning of a dream according to Freud.

Collective unconscious

Jung's concept of a shared repository of ancestral information and archetypes.

Lucid dream

A dream state in which the dreamer becomes aware they are dreaming.

Insomnia

Difficulty falling or staying asleep at least three nights weekly for one month.

Parasomnia

Sleep disorders involving unwanted motor behaviors or experiences during sleep.

REM sleep behavior disorder

Loss of normal REM muscle paralysis, leading to physical activity during dreaming.

Restless leg syndrome

Uncomfortable leg sensations when falling asleep, relieved by movement.

Night terrors

NREM sleep episodes causing panic, screaming, or attempts to escape.

Obstructive sleep apnea

Sleep breathing disruption caused by a physical blockage of the airway.

Central sleep apnea

Sleep breathing disruption occurring when the central nervous system fails to initiate breaths.

Sudden Infant Death Syndrome (SIDS)

An infant under 12 months unexpectedly stops breathing and dies during sleep.

Narcolepsy

An irresistible urge to fall asleep during waking hours, often triggered by stress.

Cataplexy

A symptom of narcolepsy involving sudden loss of voluntary muscle tone.

Hypnagogic hallucinations

Vivid, dream-like hallucinations experienced while falling asleep, associated with narcolepsy.