CCSH key terms

The predictable pattern and timing of sleep stages across a night, including light sleep, deep sleep, and REM periods. Scoring the architecture helps clinicians judge whether sleep is organized normally.

Non-rapid eye movement sleep, the portion of sleep divided into stages N1, N2, and N3. It ranges from brief light sleep to slow-wave deep sleep and supports restoration and memory consolidation.

Rapid eye movement sleep, a stage marked by fast eye movements, low muscle tone, and vivid dreaming. It occurs in cycles, lengthens toward morning, and is important for emotional processing and learning.

The internal roughly 24-hour clock that regulates sleep-wake timing, hormone release, and body temperature. Light exposure is its strongest cue, and misalignment can cause insomnia or excessive daytime sleepiness.

The buildup of sleep pressure during wakefulness that makes a person increasingly sleepy. It is balanced against the circadian alerting signal and clears during sleep, especially slow-wave sleep.

The amount of time it takes to fall asleep after going to bed with the intention of sleeping. Prolonged latency suggests insomnia, circadian misalignment, or another sleep disorder.

The percentage of time spent asleep while in bed, calculated by dividing total sleep time by time in bed and multiplying by 100. Values below about 85 percent often indicate insomnia or poor sleep habits.

A disorder in which the upper airway repeatedly collapses during sleep, reducing or stopping airflow despite continued breathing effort. It causes oxygen drops, arousals, and daytime sleepiness and raises cardiovascular risk.

A disorder in which breathing pauses occur without airway obstruction because the brain fails to signal the breathing muscles. It is often seen with heart failure, stroke, or opioid use.

A partial reduction in airflow during sleep that lasts at least ten seconds and is accompanied by an oxygen desaturation or an arousal. Hypopneas are counted when scoring a sleep study.

A persistent complaint of difficulty falling asleep, staying asleep, or waking too early despite adequate opportunity, with daytime consequences. It is diagnosed clinically and often treated first with cognitive behavioral therapy.

A neurological disorder causing excessive daytime sleepiness, sudden sleep attacks, and sometimes cataplexy, sleep paralysis, or hallucinations. It involves loss of hypocretin-producing neurons and is confirmed with sleep testing.

A sensorimotor disorder producing an urge to move the legs, usually in the evening or at rest, that is relieved by movement. It can delay sleep onset and is linked to iron deficiency.

A short questionnaire asking how likely a person is to doze in eight common situations, such as sitting and reading or riding as a passenger. Scores estimate general daytime sleepiness.

A screening questionnaire for obstructive sleep apnea using eight yes-or-no items: snoring, tiredness, observed apneas, pressure, body mass index, age, neck circumference, and gender. Higher scores indicate greater risk.

A daily log completed by the patient recording bedtime, sleep onset, awakenings, wake time, naps, and caffeine or alcohol use. It reveals sleep patterns over one to two weeks.

An overnight laboratory test that records brain waves, eye movements, muscle tone, breathing, oxygen saturation, heart rhythm, and limb movements. It is the reference standard for diagnosing sleep apnea and other disorders.

The average number of apneas plus hypopneas per hour of sleep on a sleep study. It grades sleep apnea severity and guides treatment decisions, with higher values indicating more severe disease.

A brief awakening or lightening of sleep lasting at least three seconds, visible on the sleep study as a sudden shift in brain wave frequency. Frequent arousals fragment sleep and cause daytime fatigue.

The number of times per hour of sleep that blood oxygen falls by a specified amount, usually three or four percentage points. It reflects the severity of intermittent hypoxemia in sleep apnea.

A brief arousal following increased breathing effort without a full apnea or hypopnea. It is scored when airflow is limited and breathing effort rises, and it can cause symptoms even with a low apnea-hypopnea index.

A portable recording done at home that typically measures airflow, breathing effort, oxygen saturation, and sometimes body position. It is used for uncomplicated suspected obstructive sleep apnea but can underestimate severity.

A single overnight sleep study in which the first part is diagnostic and the second part is used to start and adjust positive airway pressure. It is chosen when apnea is clearly severe early in the night.

A daytime test consisting of four or five scheduled naps that measures how quickly a person falls asleep and whether REM sleep appears early. It helps diagnose narcolepsy and idiopathic hypersomnia.

A wrist-worn device that estimates sleep and wake patterns from movement over days or weeks. It supports sleep diaries and helps assess circadian rhythm disorders and treatment response.

The process of adjusting positive airway pressure during sleep to find the lowest pressure that keeps the airway open and breathing normal. It may be done in a laboratory or automatically by an auto-titrating device.

A treatment that delivers a steady stream of air through a mask to splint the upper airway open during sleep. It is the most effective therapy for obstructive sleep apnea when used consistently.

The apnea-hypopnea index measured while a patient is using positive airway pressure therapy. A low residual index indicates the treatment is effectively controlling breathing events.

Air escaping around or through the mask seal during positive airway pressure therapy. Unintentional leak can reduce pressure, cause dry eyes or noise, and interfere with sleep and adherence.

The degree to which a patient uses prescribed positive airway pressure consistently, commonly defined as at least four hours per night on most nights. Better adherence predicts improved symptoms and cardiovascular outcomes.

A custom-made device worn in the mouth during sleep that holds the lower jaw forward to keep the upper airway open. It is an alternative for mild to moderate obstructive sleep apnea or when positive airway pressure is not tolerated.

A structured, evidence-based treatment that changes unhelpful sleep thoughts and behaviors using techniques such as stimulus control, sleep restriction, and relaxation. It is recommended as first-line therapy for chronic insomnia.

A collaborative counseling style that helps patients explore their own reasons for change while respecting their autonomy. It uses open questions, reflections, and affirmation to strengthen commitment to sleep treatment.

A teaching method in which the patient explains or demonstrates what was taught in their own words. It lets the educator confirm understanding and correct misunderstandings before the patient goes home.

The ability to obtain, understand, and use health information to make decisions. Low health literacy calls for simpler language, pictures, and repeated teaching about sleep devices and treatments.

A gradual, step-by-step approach to help a patient become comfortable with a mask or device, starting with brief awake practice and increasing wear time. It reduces anxiety and improves acceptance of therapy.

The process of explaining a test or treatment, its risks, benefits, and alternatives, and confirming the patient voluntarily agrees. It must be documented and tailored to the patient's understanding.

A federal law that protects the privacy and security of health information. It limits who may access patient records and requires safeguards for discussing sleep study results and treatment data.

The range of duties and decisions a health professional is legally and ethically permitted to perform based on training, licensure, and employer policy. Working outside it can harm patients and create liability.

The written record of patient assessment, education, interventions, and outcomes. It supports continuity of care, justifies billing, and provides legal evidence that appropriate care was delivered.