Sleep and Circadian Rhythms

Vocabulary flashcards derived from the lecture notes on sleep stages, circadian rhythms, and related disorders.

Theta Waves

Brain waves associated with the first stage of sleep.

Sleep Spindles

Bursts of rhythmic brain activity that occur during stage two of sleep.

K Complexes

Large waves that react to external stimuli during stage two of sleep.

Delta Sleep

Stages three and four of sleep characterized by slow brain waves known as delta waves.

REM Sleep

Fourth stage of sleep characterized by rapid eye movement, increased respiration, and brain activity similar to wakefulness.

Circadian Rhythm

Biological process that helps regulate sleep and waking cycles based on light and dark cycles.

Suprachiasmic Nucleus (SCN)

Cluster of neurons in the hypothalamus that acts as the internal clock regulating circadian rhythms.

Melatonin

Hormone that regulates sleep-wake cycles and is lowest in the morning and highest at night.

Narcolepsy

Neurological disorder characterized by uncontrollable episodes of falling asleep during the day.

Cataplexy

Sudden loss of muscle tone often triggered by strong emotions, associated with narcolepsy.