Unit 2: Sleep & Dreams

Vocabulary flashcards covering circadian rhythms, sleep stages (NREM-1, NREM-2, NREM-3, REM), brain structures involved in sleep, and major sleep disorders from Unit 2: Sleep & Dreams.

Circadian Rhythm

The internal biological clock that regulates bodily rhythms such as body temperature and wakefulness, where thinking and memory are sharpest at peak circadian arousal.

Circadian Peak Shift

A developmental shift occurring around age 20 (and potentially earlier for women), transitioning from adolescent circadian performance that improves throughout the day to older adult performance that declines throughout the day.

Onset of Sleep

The physiological transition marking the 'unremembered moment,' occurring as different parts of the cerebral cortex cease communicating with one another.

Sleep Cycles (Aserinsky, 1988)

A recurring 90-minute biological pattern during which an individual progresses through four distinct sleep stages.

NREM-1

A brief, light stage of non-rapid eye movement sleep that can include sensory hallucinations as sleep sets in.

NREM-2

A stage of non-rapid eye movement sleep lasting approximately 20 minutes, characterized primarily by the appearance of sleep spindles.

Sleep Spindles

Bursts of rapid, rhythmic brain-wave activity that specifically characterize NREM-2 sleep.

NREM-3

A deep non-rapid eye movement sleep stage lasting approximately 30 minutes, characterized by slow delta waves and the occurrence of night terrors.

Delta Waves

Large, slow brain waves associated with deep sleep during stage NREM-3.

REM Sleep

A sleep stage lasting about 10 minutes per cycle during ascension from deep sleep, characterized by rapid brain waves resembling wakefulness, rapid eye movement every 30 seconds or so, emotional story-like dreams, and genital arousal (except during nightmares).

Paradoxical Sleep

Another term for REM sleep, referencing the paradox where the brain's motor cortex is internally active, yet voluntary muscle movement is prevented.

Pons (in Sleep)

The brainstem structure that blocks incoming and outgoing signals to and from the active motor cortex during REM sleep, producing sleep paralysis.

Insomnia

A sleep disorder affecting 1 in 10 adults characterized by persistent problems in falling or staying asleep; often exacerbated because sleeping pills and alcohol reduce REM sleep.

Narcolepsy

A sleep disorder affecting 1 in 2,000 people, caused by the absence of the hypothalamic neural center that produces the neurotransmitter orexin.

Orexin

A neurotransmitter produced by a neural center in the hypothalamus whose absence is responsible for narcolepsy.

Sleep Apnea

A sleep disorder characterized by temporary cessations or loss of breath during sleep.

Night Terrors

A sleep disorder occurring primarily in children during NREM-3 sleep, involving intense fear and autonomic arousal.

Somnambulism

The clinical term for sleepwalking, which along with sleep-talking occurs outside of REM sleep.

REM Sleep Behavior Disorder

A sleep disorder characterized by the absence of normal REM motor inhibition, leading individuals to physically act out their dreams.