Small words. Important differences.

Open a term for a full explanation with examples, sources and related reading.

Airway obstructionobstruction · upper airway obstruction

Obstruction means that a passage is blocked or narrowed. In information about snoring and sleep apnea, it often refers to the upper airway. The word describes a mechanism; it does not identify the exact location or determine treatment on its own.

Read the full explanation 2 min read

Sleep apnea: symptoms, testing and treatment Nasal airway Obstructive sleep apnea (OSA)

Sources: NHLBI: What Is Sleep Apnea? · AASM: Rules for Scoring Respiratory Events in Sleep (2012 update)

Apneabreathing pause

Apnea is an episode in which airflow stops or nearly stops. In sleep medicine, it is a specific breathing event identified from recorded signals. The word describes an event; it does not, by itself, name a diagnosis.

Read the full explanation 2 min read

Sleep apnea: symptoms, testing and treatment Hypopnea Obstructive sleep apnea (OSA)

Sources: AASM: Rules for Scoring Respiratory Events in Sleep (2012 update) · NHLBI: What Is Sleep Apnea?

Back sleeping (supine position)supine · supine sleeping position

Back sleeping means lying on your back with the front of the body facing upward. The medical term is supine. In sleep medicine, it is used to describe body position or compare breathing in different positions.

Read the full explanation 2 min read

Why do people snore? Causes and next steps Positional therapy Snoring

Sources: ADA: Obstructive Sleep Apnea · NHLBI: Treatment

Bite and occlusionocclusion · dental bite

Your bite is the way your upper and lower teeth meet. Dentists also use the word occlusion. It describes tooth contact and should be distinguished from the jaw joints and the muscles used for chewing.

Read the full explanation 2 min read

Oral appliance side effects and follow-up Mandible Night guard and dental splint

Sources: MedlinePlus: Malocclusion of Teeth · NIDCR: Temporomandibular Disorders

Central sleep apnea (CSA)CSA · central apnea

Central sleep apnea, or CSA, is a sleep-related breathing disorder involving interruptions in the signals that drive breathing. During a central apnea, breathing effort is absent. This differs from an obstructive event in which effort continues against a blocked airway.

Read the full explanation 2 min read

Sleep apnea: symptoms, testing and treatment Apnea Obstructive sleep apnea (OSA)

Sources: American Thoracic Society: Central Sleep Apnea in Adults · NHLBI: What Is Sleep Apnea?

Checking treatment effectivenessfollow-up testing · efficacy assessment

Checking treatment effectiveness means assessing whether a treatment achieves its intended goal. For sleep apnea, follow-up needs to address breathing and the clinical treatment goal, as well as any improvement in bedroom noise.

Read the full explanation 3 min read

Sleep apnea: symptoms, testing and treatment Sleep apnea evaluation Home sleep apnea test (HSAT)

Sources: AASM longitudinal testing guidance, 2021 · AADSM updated standards, April 2025

CPAPcontinuous positive airway pressure · PAP

CPAP stands for continuous positive airway pressure. It delivers pressurized air through a mask to help keep the airway open during sleep. The name describes the way pressure is delivered.

Read the full explanation 2 min read

Snoring and sleep apnea treatment: how options differ Obstructive sleep apnea (OSA) Oxygen saturation

Sources: NHLBI: CPAP · NHLBI: Treatment

Custom fitcustom-made appliance · individual fitting

Custom fitting means making or adapting a device for the person who will use it. For an oral appliance, this involves the teeth and mouth as well as the way the device fits into an individual course of treatment.

Read the full explanation 2 min read

Oral appliance therapy for snoring and sleep apnea Sleep apnea oral appliance Bite and occlusion

Sources: AADSM updated standards, April 2025 · AADSM patient fact sheet

Daytime sleepinessdrowsiness · excessive daytime sleepiness · EDS

Sleepiness means a tendency to fall asleep or difficulty staying awake. It is not exactly the same as feeling exhausted or having little energy. The distinction can make it easier to explain sleep-related concerns at an appointment.

Read the full explanation 2 min read

Sleep apnea symptoms: what to notice Obstructive sleep apnea (OSA) Sleep apnea evaluation

Sources: MedlinePlus: Drowsiness · NHLBI: Diagnosis

Evidence basesupporting evidence · source quality

An evidence base is the collection of sources and information used to support an explanation or claim. The evidence needs to match the question. A source can be useful for one purpose without answering another.

Read the full explanation 3 min read

Our editorial principles Checking treatment effectiveness Starting price

Sources: FTC: Health Products Compliance Guidance · Cochrane: What Are Systematic Reviews?

Home sleep apnea test (HSAT)HSAT · home sleep test · respiratory polygraphy

A home sleep apnea test, or HSAT, records selected breathing-related signals while you sleep at home. Depending on the device, these may include airflow, breathing effort, pulse, and oxygen saturation. It is a medical test ordered for an appropriate clinical situation.

Read the full explanation 2 min read

Sleep apnea testing: home tests and sleep studies Polysomnography (PSG) Oxygen saturation

Sources: AASM: Clinical Use of a Home Sleep Apnea Test (2018 position statement) · NHLBI: Diagnosis

Hypopneapartial airflow reduction

A hypopnea is a breathing event involving a partial reduction in airflow. To be counted in a sleep study, it must meet defined clinical criteria. The term is more precise than describing breathing as weak or snoring as quiet.

Read the full explanation 2 min read

Sleep apnea testing: home tests and sleep studies Apnea Oxygen saturation

Sources: AASM Sleep ISR: Scoring Respiratory Events · AASM: Polysomnography for OSA Should Include Arousal-Based Scoring (2018)

Mandiblelower jaw · mandibular advancement

The mandible is the lower jawbone. It holds the lower teeth and moves when you chew and speak. In information about sleep apnea appliances, you will often see it in the term mandibular advancement.

Read the full explanation 2 min read

Oral appliance therapy for snoring and sleep apnea Bite and occlusion Sleep apnea oral appliance

Sources: NCI Dictionary: Mandible · NIDCR: Temporomandibular Disorders

Nasal airwaynasal passage · nasal airflow · nasal obstruction

The nasal airway is the passage air travels through inside the nose. People also use the term to describe how easily air moves through it. Reduced nasal airflow usually means the nose feels narrow, blocked, or difficult to breathe through.

Read the full explanation 3 min read

What helps with snoring? Comparing your options Airway obstruction Snoring

Sources: MedlinePlus: Nose Injuries and Disorders · NHLBI: What Is Sleep Apnea?

Night guard and dental splintocclusal splint · stabilization splint · bruxism guard

A night guard is a dental appliance commonly used to protect teeth from grinding or clenching. Related devices are called dental splints or stabilization appliances. The intended purpose should be explained by your dentist; these names do not identify one universal treatment.

Read the full explanation 3 min read

Oral appliance therapy for snoring and sleep apnea Bite and occlusion Sleep apnea oral appliance

Sources: NIDCR: Bruxism · NIDCR: Temporomandibular Disorders

Obstructive sleep apnea (OSA)OSA · obstructive sleep apnoea

Obstructive sleep apnea, or OSA, involves repeated breathing disruptions because the upper airway narrows or closes during sleep. The body may keep trying to breathe even when air cannot pass normally.

Read the full explanation 2 min read

Sleep apnea: symptoms, testing and treatment Airway obstruction Apnea

Sources: NHLBI: What Is Sleep Apnea? · AASM: Rules for Scoring Respiratory Events in Sleep (2012 update)

Oxygen saturationSpO2 · SpO₂ · pulse oximetry

Oxygen saturation describes the proportion of hemoglobin in the blood that is carrying oxygen. A pulse oximeter uses light to estimate saturation. The estimate is usually called SpO₂ and is displayed as a percentage.

Read the full explanation 2 min read

Sleep apnea testing: home tests and sleep studies Home sleep apnea test (HSAT) Polysomnography (PSG)

Sources: MedlinePlus: Pulse Oximetry · FDA: Pulse Oximeters

Polysomnography (PSG)PSG · overnight sleep study · in-lab sleep study

Polysomnography, or PSG, is a detailed sleep study. It combines signals used to assess sleep and sleep stages with measurements such as breathing, oxygen saturation, and movement.

Read the full explanation 2 min read

Sleep apnea testing: home tests and sleep studies Home sleep apnea test (HSAT) Oxygen saturation

Sources: NHLBI: Sleep Studies · MedlinePlus: Sleep Study

Positional therapyposition therapy · side-sleeping intervention

Positional therapy aims to change how someone lies during sleep. In snoring and sleep apnea care, the goal is often to reduce time spent sleeping on the back. Its relevance depends on the person and the breathing pattern being treated.

Read the full explanation 3 min read

What helps with snoring? Comparing your options Back sleeping (supine position) Obstructive sleep apnea (OSA)

Sources: Cochrane: Positional Therapy for Obstructive Sleep Apnoea (2019) · European Respiratory Society: Non-CPAP Therapies for OSA (2021 guideline)

Sleep apnea evaluationdiagnostic evaluation · sleep evaluation · workup

An evaluation is the process of gathering and interpreting information to understand symptoms or a suspected condition. For snoring and sleep concerns, it can include a conversation, observations, examination, and testing. A sleep study is one possible part of that process.

Read the full explanation 3 min read

Sleep apnea testing: home tests and sleep studies Home sleep apnea test (HSAT) Polysomnography (PSG)

Sources: NHLBI: Diagnosis · AASM diagnostic testing guideline, 2017, original paper

Sleep apnea oral appliancemandibular advancement device · MAD · mandibular repositioning device

A common oral appliance for obstructive sleep apnea holds the lower jaw slightly forward during sleep. It is often called a mandibular advancement device, or MAD. The name describes a treatment approach; it does not tell you whether a particular device is appropriate for you.

Read the full explanation 2 min read

Oral appliance therapy for snoring and sleep apnea Mandible Night guard and dental splint

Sources: ADA: Obstructive Sleep Apnea · FDA intraoral-device special-controls guidance

Snoringsnore · snoring sound

Snoring is sound produced when tissue in the upper airway vibrates during sleep. The term describes a sound and a mechanism. It does not establish a sleep disorder or identify the right treatment on its own.

Read the full explanation 2 min read

Why do people snore? Causes and next steps Apnea Obstructive sleep apnea (OSA)

Sources: ADA: Obstructive Sleep Apnea · NHLBI: What Is Sleep Apnea?

Starting pricefrom price · advertised minimum price

A starting price is the advertised minimum charge for a product or service. It offers an initial reference point, but it may not represent the total cost of what you need. To compare offers, you also need to know what each price includes.

Read the full explanation 3 min read

Oral appliance costs: what to ask before treatment Custom fit Checking treatment effectiveness

Titrationappliance adjustment · calibration · mandibular advancement titration

Titration means gradually adjusting treatment toward an intended goal. For an adjustable mandibular advancement appliance, it refers to changing how far forward the lower jaw is held. It is a planned process, not a goal of maximum advancement.

Read the full explanation 2 min read

Oral appliance therapy for snoring and sleep apnea Sleep apnea oral appliance Mandible

Sources: AADSM updated standards, April 2025 · AASM longitudinal testing guidance, 2021