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Overview of polysomnography in infants and children

Overview of polysomnography in infants and children
Author:
Madeleine Grigg-Damberger, MD
Section Editor:
Ronald D Chervin, MD, MS
Deputy Editor:
April F Eichler, MD, MPH
Literature review current through: Dec 2022. | This topic last updated: Apr 15, 2022.

INTRODUCTION — Polysomnography (PSG) is a diagnostic sleep medicine tool during which multiple different physiologic parameters are continuously and simultaneously recorded across a sleep period to characterize sleep and identify sleep disorders. Through simultaneous recording of multiple physiologic parameters, changes in sleep/wake state or alterations in one parameter can be correlated with other signals. Thus, PSG is a much more powerful diagnostic tool than can be provided by recording only one or two simultaneous physiological measures.

Younger and younger children are being referred to sleep specialists and sleep laboratories for evaluation of sleep disorders; PSG is often required for diagnosis, and sometimes treatment. While PSG is considered a relatively painless, noninvasive procedure by most adults, it can be challenging and even frightening for children and therefore requires special considerations.

This topic will provide an overview of PSG in infants and children, including indications for testing, derived information, techniques for obtaining useful data, and scoring and interpretation. An approach to the assessment and classification of specific sleep disorders in children is discussed separately. (See "Assessment of sleep disorders in children".)

TYPES OF SLEEP STUDIES — The American Academy of Sleep Medicine (AASM) [1] and the Centers for Medicaid and Medicare Services (CMS) [2] identify four classes of sleep studies based upon how channels are recorded and whether a sleep technologist is present throughout the recording to provide oversight ("attended" or "unattended").

A level 1 polysomnography (PSG) is performed in a sleep laboratory with a sleep technologist present, recording a minimum of seven channels including electroencephalography (EEG), electrooculography (EOG), submentalis (chin) electromyography (EMG), electrocardiogram (ECG)/heart rate, and pulse oximetry (SpO2).

A level 2 PSG is simply a level 1 PSG which is recorded unattended, in or out of the sleep laboratory.

A level 3 study records a minimum of four channels, including ventilation, oximetry, ECG, or heart rate, and is done at home or outside of the sleep laboratory, unattended. The available home sleep apnea test (HSAT) devices most often record nasal pressure, respiratory effort, body position, heart rate, and snoring. Some also record actigraphy and peripheral arterial tonometry (PAT) in order to provide surrogate measures of sleep and arousal [3].

A level 4 study records two to three cardiorespiratory signals (most often airflow, SpO2, and heart rate) and is typically done at home, unattended.

Comprehensive in-laboratory overnight PSG (ie, level 1 PSG) is still regarded as the gold standard method for recording sleep/wake states and for diagnosing obstructive sleep apnea (OSA) and other sleep disorders in children, for several reasons:

A technologist is present throughout to identify problems, repair or replace equipment, and test treatment(s) if needed.

The severity of sleep-disordered breathing (ie, the apnea hypopnea index [AHI], mean number of apneas and hypopneas per hour) can be derived from sleep time, rather than time in bed. AHI based on time in bed may be falsely low, underestimating OSA severity if too much of the night is spent awake.

Nonrespiratory sleep disorders and other disruptors of sleep can also be identified.

However, Level 1 PSG is expensive and time- and labor-intensive to record, score, and read. Availability is often limited, and wait times can be long in some regions, especially for infants and young children [4-6].

For these reasons and others, level 3 studies (ie, home sleep apnea testing) are increasingly used in adults to diagnose OSA. There are more limited data on level 3 studies in children, and this has not yet become standard practice. (See 'Alternative studies' below and "Home sleep apnea testing for obstructive sleep apnea in adults".)

INDICATIONS FOR POLYSOMNOGRAPHY — Polysomnography (PSG) plays a role in the diagnosis and treatment of a variety of respiratory and nonrespiratory sleep disorders in children [7-12]. Specific indications for PSG in children include the following [9,10,13]:

Diagnosis of sleep-related breathing disorders (SRBD) such as obstructive sleep apnea (OSA), central sleep apnea (CSA), or sleep-related hypoventilation disorders. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Polysomnography' and "Evaluation of sleep-disordered breathing in patients with neuromuscular and chest wall disease", section on 'Polysomnography' and "Disorders of ventilatory control", section on 'Congenital central hypoventilation syndrome' and "Congenital central hypoventilation syndrome and other causes of sleep-related hypoventilation in children".)

Preoperative assessment before upper airway surgery (eg, adenotonsillectomy), particularly in children with snoring, signs and symptoms of OSA, or other high-risk features (eg, obesity with a body mass index [BMI] ≥95th percentile, Down syndrome [DS], craniofacial abnormalities, neuromuscular disorders, sickle cell disease). (See "Management of obstructive sleep apnea in children" and "Tonsillectomy and/or adenoidectomy in children: Preoperative evaluation and care", section on 'Polysomnogram'.)

Titration of positive airway pressure (PAP) therapy for SRBD. (See "Continuous positive airway pressure (CPAP) for pediatric obstructive sleep apnea".)

Evaluation of treatment efficacy of PAP, oral appliances, weight loss, or upper airway surgeries in patients with SRBD. (See "Management of obstructive sleep apnea in children".)

Evaluation and diagnosis of suspected narcolepsy type 1 or 2, idiopathic hypersomnia, and other central hypersomnias, followed by a multiple sleep latency test (MSLT). (See "Quantifying sleepiness", section on 'Multiple sleep latency test (MSLT)'.)

Diagnosis of rapid eye movement sleep behavior disorder (RBD) and/or rapid eye movement sleep without atonia (RWA). (See "Rapid eye movement sleep behavior disorder".)

Evaluation of paroxysmal nocturnal events with expanded EEG and video-PSG in selected patients, such as those with atypical features, clinical suspicion for sleep-related seizures, or potentially injurious behaviors. (See "Approach to abnormal movements and behaviors during sleep", section on 'Evaluation'.)

Assessment of selected children with suspected restless legs syndrome (RLS), when additional supportive data (eg, demonstration of periodic leg movements) are desired to help confirm the diagnosis. In other children without RLS, PSG can be useful to diagnose periodic limb movement disorder (PLMD) or restless sleep disorder. (See "Sleep-related movement disorders in childhood", section on 'Restless sleep disorder'.)

Suspected sleep-related epilepsy when the initial clinical evaluation and standard EEG are inconclusive, to help distinguish from parasomnias. (See "Sleep-related epilepsy syndromes".)

Confirm and treat congenital central alveolar hypoventilation syndrome, including late-onset types. (See "Congenital central hypoventilation syndrome and other causes of sleep-related hypoventilation in children".)

PSG is not the best first test for evaluating insomnia, RLS, circadian rhythm sleep-wake disorders, typical uncomplicated parasomnias, sleep-related epilepsy, depression, chronic lung disease, sleep-related bruxism, or behaviorally-based insomnia [10,13]. Although PSG is not routinely indicated in the evaluation of sleepwalking and sleep terrors, it should be performed when there is clinical suspicion for another sleep disorder (eg, OSA) that may be precipitating partial arousals from sleep. (See "Parasomnias of childhood, including sleepwalking", section on 'Investigations'.)

CHILD-FRIENDLY TECHNIQUES — Although noninvasive, polysomnography (PSG) can be intrusive, onerous, and even frightening for children. Adopting and routinely employing child-friendly, family-centered PSG practices can increase the likelihood of obtaining an interpretable PSG and of having the patient return for follow-up [14].

Child-friendly PSG techniques begin with preparation and education of the child and family, ideally before they come to the laboratory. The techniques reviewed below are derived from expert experience in recording over 1000 sleep studies in children [15].

Preparation — Preparing the child and caregiver before the PSG lessens anticipatory anxiety and procedural distress, increases cooperation, improves parent/caregiver satisfaction, and helps the child tolerate future medical procedures.

When a sleep study is indicated, the clinician should describe the procedure in age-appropriate, positive terms and provide an explanation of why the study is needed.

Written and visual preparatory material can be very helpful. This may include pamphlets, an introductory video showing how PSG is done, and a tour of the sleep laboratory.

Encourage the child to bring personal items from home (eg, favorite toy, blanket, stuffed animal, doll, pajamas).

Clinicians and staff should identify patients who may need additional assistance and support ahead of time, in order to arrange for 1:1 staffing if needed. Such patients may include those who are medically fragile, developmentally delayed, or who have had difficulty tolerating other procedures. Examples of screening questions include:

How easily does your child tolerate tests, surgeries, medical procedures, or even sitting still for haircuts?

Does your child have sensory sensitivities (noise, touch, smell, textures)?

Does your child have any home medical equipment or specialized medical needs (eg, feeding tubes, suctioning devices, peritoneal dialysis, mechanical ventilator, tracheostomy caps)?

Allow at least 90 minutes before usual sleep onset in children younger than six years of age (or any children with developmental disabilities) to permit adjustment to the laboratory and hook-up; two hours lead-time is needed for a PSG that includes expanded EEG montages.

Longer technologist shifts are needed to record PSG in children because of their longer sleep times: 12 to 16 hours in infants 4 to 12 months; 11 to 14 hours for ages 1 to 2 years; 10 to 13 hours for ages 3 to 5 years; and 9 to 12 hours for ages 6 to 12 years [16]. It is useful to extend the sleep recording time to capture sufficient rapid eye movement (REM) sleep in the morning (when apnea is often worse).

If it seems likely the child will have great difficulty cooperating for PSG (or has failed it before), and the PSG is crucial for medical decision-making, consider involving a child life specialist to prepare the child for PSG [17,18]. A formal desensitization protocol, in which children are gradually exposed to portions of the PSG equipment at home in the weeks leading up to a study, can be taught to caregivers and may increase the likelihood of a successful study in children with autism spectrum disorder or developmental delay [19].

Avoid performing a PSG when a patient is acutely unwell or on the same day as immunization [20]. Acute illness may exacerbate sleep-disordered breathing or other sleep problems.

Unless the PSG is performed for a special purpose (eg, suspected narcolepsy or parasomnia), patients should maintain their usual sleep habits prior to the study.  

Children should avoid caffeinated or energy drinks the day of the PSG.

Medications the child takes should be reviewed. Hypnotics, sedatives, and opioid-based analgesics can worsen or induce sleep-disordered breathing and may alter sleep architecture and arousal thresholds [20]. Antidepressants, antipsychotics, benzodiazepines, and barbiturates can alter sleep architecture, arousal thresholds, sleep spindles, muscle tone, and leg movements. The clinician ordering the PSG needs to decide whether clonidine, caffeine, melatonin, nasal steroids, antihistamines, methylphenidate and dexamphetamine should be continued the night of the study. In some cases, withdrawal of a chronic medication or substance may further disturb sleep.

Sedation to obtain sleep in a pediatric PSG is best avoided.

Electrode application

Children younger than six years of age have limited ability to cooperate with the PSG procedure and set up, and even older children may regress under stressful conditions. Younger children need short, concrete explanations. Patience, flexibility, and a playful and positive attitude can go a long way.

Avoid laying children down or restraining them to apply sensors. Instead, position the child (who can sit) in the parent/caregiver's lap (chest-to-chest hugging, sitting sideways or forward). Children feel less vulnerable when placed in these "positions of comfort" and are better able to maintain a sense of control and cooperation.

Seek out the parent/caregiver's help and advice. What has helped the child manage hard things in past? What may help the child cooperate with the setup?

Use child-friendly terminology for the PSG sensors and explanations for the setup and procedure [15].

Medical play can help the child cooperate [21-24]:

Demonstrate how and where a sensor is applied on their doll or stuffed animal before placing it on the child.

Encourage the child to touch the sensors and equipment.

Ask the child to blow bubbles up in the air while attaching the chin electromyography (EMG), or put the play electrode on the doll while you place one on the child.

Give the child choices: Do I put on the leg or chin sticky first? Which finger for your finger nightlight? Would like to hold the mirror and watch me put stickers on your chin?

Allow extra time and time-outs for children who become frightened, emotionally labile, or overwhelmed.

Provide a distraction box (eg, stickers, musical and light-up toys, pop-up books, bubbles) to engage the child while sensors are applied [25]. Praise the child every step of the way.

Nasal airflow sensors are particularly odious to children, and the technologist may need to wait until the child is deeply asleep to apply them. Sometimes, the clinician may have to accept recording only pulse oximetry (SpO2) and respiratory impedance plethysmography (RIP), together with quality video and direct observations by the technologist.

RECORDED SIGNALS — Polysomnography (PSG) data are recorded, scored, and analyzed in children using criteria, recommendations, and technical specifications detailed in the American Academy of Sleep Medicine (AASM) Manual for the Scoring of Sleep and Associated Events, which is updated regularly [26]. While most aspects of PSG recording are similar for adults and children, there are major differences in the scoring rules for sleep/wake states and respiration.

Evaluation of sleep/wake state — Sleep/wake states and arousals are identified and classified (scored) using three biological parameters: electroencephalography (EEG), electrooculography (EOG), and submentalis (chin) surface electromyography (EMG) activity.

EEG recorded from the frontal, central, and occipital scalp regions permits recognition of sleep/wake state, as follows:

Wakefulness (W) is indicated by the presence of a dominant posterior rhythm over the occipital regions, which is attenuated by eye opening (figure 1).

Slow eye movements over the frontal regions are typically the first sign of non-rapid eye movement (NREM) stage N1 sleep (figure 2); vertex waves, typically maximal over the central regions, appear later in stage N1 (but are also seen in stage N2) (figure 3).

Sleep spindles of stage N2 sleep (which may linger into early N3) first appear over the midline central region in infants at 44 to 48 weeks post-conceptional age. Until 13 years of age, sleep spindles are maximal over the frontal and central regions (figure 4). After age 13, sleep spindles are most prominent and of highest amplitude over central regions (figure 5). Occasionally, frontal sleep spindles are seen in young adults in transition to stage N2 sleep.

K-complexes of stage N2 sleep (figure 6) are often of highest amplitude over the frontal EEG regions.

High voltage slow wave activity of stage N3 sleep is typically of highest amplitude over the frontal regions and scored in these channels (figure 7).

Saw-tooth waves of REM sleep are best seen over central regions, typically accompanied by rapid eye movements, a low-voltage mixed frequency EEG, and chin EMG atonia (figure 8).

EOG detects changes in electrical fields generated by the movement of the eyeballs, which have a horizontal dipole with a strong positive charge in the cornea and a minor negative charge at the retina. Two different montages are recommended by the AASM for scoring EOG [26]. EOG data are used in several ways:

Eye movements are particularly useful in identifying sleep onset and rapid eye movement (REM) sleep (stage R) (figure 9).

Slow eye movements are the most dependable manifestation of stage N1 sleep.

Rapid eye movements are a cardinal sign of REM sleep (figure 8).

Chin EMG is used to assess axial skeletal muscle tone and activity. Most axial skeletal muscles are actively inhibited during REM sleep (save the extraocular muscles and the diaphragm), thereby preventing dream enactment.

Chin EMG tends to decrease at sleep onset, further diminishes with increasing depth of NREM sleep, and reaches its lowest level of activity in REM sleep.

The onset, presence, and offset of REM sleep is identified and scored when the chin EMG is absent or at its lowest amplitude in the recording (waveform 1).

Arousals from sleep are often accompanied by transient increases in muscle tone, evident on the chin EMG (figure 2).

The AASM scoring manual requires a transient increase in chin EMG lasting >1 second to score an EEG arousal during REM sleep (but not in NREM sleep) [26].

Respiratory monitoring — Almost all of the sensors used to monitor breathing and gas exchange during sleep provide qualitative, not quantitative, data. Because of this, redundant measures of respiration during sleep are needed. This permits correlation of changes in respiration, pulse oximetry, carbon dioxide (CO2), and electrocardiogram (ECG) with three additional measures: body position, sleep/wake stages, and arousals. These cross-correlations are necessary for several reasons:

Sleep-disordered breathing often disrupts sleep, causing arousals or awakenings.

Sleep-disordered breathing is more often worse when sleeping supine (and sometimes prone in young children [27]) or during REM sleep [28].

Desaturations related to sleep-disordered breathing are often worse during REM sleep, and related cardiac arrhythmias or sinus pauses are particularly common during this time.

Sleeping through such desaturations (without an arousal or awakening) is an important clinical observation, increasing the potential seriousness of the sleep-related breathing disorder (SRBD).

Multiple sensors are used during PSG to monitor for sleep-disordered breathing. These variables are used to detect respiratory events, such as apneas and hypopneas, and to calculate summary measures (eg, apnea hypopnea index, respiratory distress index) (table 1). (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Polysomnography'.)

Oronasal thermal and nasal pressure sensors – These sensors monitor air flow through the nose and mouth; the thermal sensor best identifies apnea, and the nasal pressure sensor best identifies hypopneas and respiratory event related arousals (RERAs).

Snoring microphone – A snoring microphone detects the presence and volume of snoring.

Respiratory impedance plethysmography (RIP) – RIP provides a measure of respiratory effort as manifested by expansion and relaxation of the thorax and abdomen during inspiration and expiration, respectively.

Pulse oximetry – A sensor placed over the finger, earlobe, or toe continuously measures pulse oxyhemoglobin saturation, heart rate, and pulse amplitude to detect hypoxemia.

ECG – PSG typically records a single ECG channel (lead I). SRBD can affect cardiac rate and rhythm (often bradycardia during an apnea, tachycardia upon arousal).

CO2 monitoring – Monitoring CO2 is used to identify sleep-related hypoventilation. End-tidal CO2 is measured using a nasal cannula placed in the nostrils. Transcutaneous CO2 is measured using sensors attached to upper arm, trunk, or forehead.

During a diagnostic study, either end-tidal CO2 or transcutaneous CO2 can be recorded. During a positive airway pressure (PAP) titration study or use of supplemental oxygen, transcutaneous CO2 is often preferred, because the effectiveness of the end-tidal CO2 cannula is reduced when oxygen or PAP is delivered.

Esophageal pressure monitoring – An esophageal pressure sensor is used in some sleep laboratories to measure changes in intrathoracic pressure and assess work of breathing during sleep.

Body position monitor – A body position monitor detects change in body position. Obstructive sleep apnea may be worse when the child is lying supine or during a particular sleep state (more often REM sleep).

Continuous positive airway pressure (CPAP) flow and leak – When PSG is being used to titrate positive airway pressure therapy, nasal pressure and end-tidal CO2 sensors are turned off. CPAP air flow, pressure, and leak from the CPAP mask are then measured.

Detection of movements and behaviors — EMG activity from the left and right anterior tibialis muscles (left leg, right leg) with time-locked video is routinely recorded in order to:

Identify periodic limb movements during wake and sleep, which can be a marker of periodic limb movement disorder (PLMD) or restless legs syndrome/Willis-Ekbom disease (RLS/WED). (See "Restless legs syndrome and periodic limb movement disorder in children", section on 'Polysomnography and accelerometry'.)

Identify inappropriate muscle activity during REM sleep when muscle atonia should be present (so-called REM sleep without atonia [RWA], as seen in REM sleep behavior disorder [RBD]). Of note, RWA and some of the movements of RBD may be missed on PSG, as they occur more commonly in the chin and wrist extensors (which are not routinely recorded) than in the anterior tibialis [29]. To detect RWA in REM sleep, the AASM scoring manual recommends optional placement of left and right flexor digitorum superficialis and extensor digitorum communis surface EMG [26]. (See "Parasomnias of childhood, including sleepwalking", section on 'Rapid eye movement sleep behavior disorder'.)

Confirm an arousal or identify excessive or inappropriate forms of muscle activity during sleep. (See "Polysomnography in the evaluation of abnormal movements during sleep".)

In our experience, 5 to 10 percent of pediatric PSGs (performed at a tertiary center) are requested for the purposes of identifying and classifying unusual, paroxysmal, excessive, or inappropriate motor or complex behaviors during sleep. These include periodic limb movements, RWA, RBD, sleep-related epilepsy, and other parasomnias. (See "Parasomnias of childhood, including sleepwalking" and "Restless legs syndrome and periodic limb movement disorder in children".)

Expanded EEG montages — The number of EEG channels used during a standard PSG (three or six) is not generally sufficient to detect or fully characterize most interictal epileptiform activity, although it may show seizures. When nocturnal seizures, epilepsy, or atypical parasomnias are suspected and routine EEG has yet to identify them, video-PSG with expanded EEG montages can be a useful next step in the evaluation. (See "Polysomnography in the evaluation of parasomnias and epilepsy".)

We typically record 18 channels of EEG in this setting. Even with 18 channels, however, some seizures may not be identified, particularly when they originate from the frontal lobe [30,31]. In one study in which blinded reviewers were provided with PSG recordings of temporal lobe seizures reformatted in 4, 7, or 18 channels, the sensitivity for detecting temporal lobe seizures improved as the number of channels increased (67, 82, and 86 percent sensitivity for 4, 7, and 18 channels, respectively) [31]. However, the sensitivity for frontal lobe seizures was far lower and did not improve with a higher number of channels. Another potential limitation is that the habitual nocturnal event may not be captured by one night of in-laboratory video-PSG, particularly if the events are NREM arousal parasomnias [32-34].

SCORING AND INTERPRETATION — Following the recording, sleep/wake states and arousals are manually scored in 30-second sequential epochs from "Lights Off" to "Lights On" by a sleep technologist based on published scoring criteria [26].

Sleep in infants zero to two months of age is scored as either non-rapid eye movement (NREM) sleep (stage N), rapid eye movement (REM) sleep (stage R), or transitional sleep (stage T) [26,35,36].

Between ages two to five months, sleep is often scored simply as stage N or stage R, although recognizable sleep spindles of stage N2 sleep are usually seen by two to three months, N3 is identifiable by four to six months, and K-complexes by six months of age [37]. When sleep spindles are present, epochs containing them can be scored as stage N2; when slow wave activity is present, epochs are scored as stage N3. (See "Stages and architecture of normal sleep" and "Sleep physiology in children", section on 'Sleep states'.)

Respiratory events are scored by the technologist using published criteria in children [38] and taking into account norms for sleep-related ventilation in children [39-44]. The presence, type, and duration of respiratory abnormalities are scored, including (table 1):

Apneas, hypopneas, respiratory event related arousals [RERAs], oxygen desaturations, increased work of breathing, hypercapnia, hypoxemia, and hypoventilation (table 1). These are defined and reviewed separately. (See "Mechanisms and predisposing factors for sleep-related breathing disorders in children", section on 'Patterns of OSA/OHV in children' and "Evaluation of suspected obstructive sleep apnea in children", section on 'Respiratory events'.)

Disturbing heart rhythms and rates, and their relation to hypoxemia and respiratory events [45].

The technologist also scores and/or tags periodic limb movements, paroxysmal motor behaviors, parasomnias, interictal discharges (IEDs), and REM sleep without atonia (RWA) [26].

Once scored, the digital polysomnography (PSG) system program tabulates and collates summaries of the data and generates a visual summary of the PSG (called a hypnogram). The scored sleep study is then reviewed, revised, and interpreted by a sleep specialist. A sleep study report is typically accompanied by tables summarizing the data, a hypnogram, and an interpretation of the findings.

Examples of abnormalities or significant findings often reported include:

Sleep-disordered breathing (eg, apneas, hypopneas).

Frequent arousals (and their causes, if apparent).

Short or delayed sleep onset latencies (some of which may represent first-night effects).

Rapid onset REM sleep latencies (ie, entry into REM sleep <15 minutes after sleep onset in infants). Sleep onset in healthy infants younger than three months is typically REM sleep. REM sleep onset is rarely seen in healthy infants after six months of age. (See "Sleep physiology in children", section on 'Infants'.)

Absence of stage R or N3 sleep (some of which may be medication or first-night effects).

Excessive loss of normal skeletal atonia during REM sleep and REM sleep behavior disorder motor events.

Excessive position shifts, sleep stage shifts, limb movements, and excessive motor activity during NREM and/or REM sleep.

Excessive amounts of transitional or indeterminate sleep.

Abnormal EEG background or indeterminate sleep/wake states.

Periodic limb movements while awake and asleep and the percentage that cause arousals/awakening.

Other parasomnias, seizures, interictal epileptiform discharges, EEG variants, or PSG artifacts.

In the appropriate clinical context, PSG often provides diagnostic certainty for a range of sleep disorders in children, including obstructive sleep apnea (OSA), central sleep apnea (CSA), narcolepsy type 1 and type 2 (in combination with the multiple sleep latency test [MLST]), and periodic limb movement disorder (PLMD). However, the significance of any PSG finding must be considered within the context of the clinical history and examination findings. The diagnostic criteria for these disorders, which incorporate both clinical and polysomnographic findings, are reviewed individually. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Diagnosis' and "Restless legs syndrome and periodic limb movement disorder in children" and "Clinical features and diagnosis of narcolepsy in children", section on 'Diagnosis'.)

LIMITATIONS — While level 1 polysomnography (PSG) provides extensive, multicomponent information on sleep, there are some limitations. A sleep study typically records only one night of sleep in the artificial environment of the sleep laboratory, which provides at best a narrow view of how a child naturally sleeps. This results in so-called first-night effects: more time supine, less rapid eye movement (REM) and stage N3 sleep, and more wake after sleep onset (WASO) and stage N1 sleep on the first night.

A limited number of prospective studies evaluating first-night effects in children and their impact on PSG results suggest the following [12,46-50]:

Children and adolescents (but perhaps not young infants) exhibit first-night effects that are comparable to those described in adults

Children with and without obstructive sleep apnea (OSA) exhibit significant night-to-night-variability in sleep parameters but not in respiratory parameters

An adaptation night is necessary if a PSG is done to study sleep architecture, but not when only the nocturnal respiratory pattern is investigated

One night of PSG is usually sufficient to confirm OSA but is not reliable for sleep architecture

These limitations are also relevant to PSG recordings performed on children who are medically sick or unstable. Results in such cases are unlikely to represent the baseline condition and should not generally be used to make long-term treatment decisions. If a bedside level 1 PSG is absolutely necessary before a child is discharged from the hospital, it should be the last test before discharge, when the child is medically stable.

SAFETY CONSIDERATIONS — Level 1 polysomnography (PSG) is a relatively safe procedure, although there are few systematic studies. One single-center retrospective review identified an adverse event reported in 58 of 36,141 PSGs performed over a five-year period (0.16 percent; 1 out of every 623 PSGs) [51]. The most common adverse events were acute chest pain or disturbing cardiac arrhythmias (29 percent) and falls (21 percent; five were in patients who had taken zolpidem).

A survey of pediatric sleep centers also identified falls out of a crib or bed as the main safety concern [52]. Most toddlers can climb out of a crib when they are about 35 inches tall and between 18 and 24 months of age. Risk factors for falls that have been identified in pediatric inpatients include episodes of disorientation, altered mobility, history of falling at home, age younger than three years, and antiseizure medication [53,54]. One study proposed a fall prevention algorithm in sleep centers, which included the following guidance [52]:

Identify patients at risk (eg, children who have fallen in last month)

Identify the appropriate bed type for the child's age and condition

Use no-skid footwear when the child is out of bed

Provide direct supervision of the child at all times, particularly when getting up to use the bathroom

Patients with known or suspected sleep-related violence, parasomnias, or seizures are at increased risk for injury when sleeping, and intervention strategies should be in place in the sleep laboratory. We and others have rarely observed instances of physical child abuse by parent or caregiver, even after they are advised that the entire procedure is being video recorded [51]. We report such cases to child protective services, and the video evidence is cited in the report.

Training staff to recognize and handle abnormalities in vital signs is mandatory. In-laboratory, out-of-hospital sleep studies require ready access to age-appropriate resuscitative equipment, training in cardiopulmonary resuscitation (CPR), and easy access to paramedic support.

ALTERNATIVE STUDIES — Although comprehensive in-laboratory polysomnography (PSG) remains the preferred and appropriate study for the evaluation of both respiratory and nonrespiratory sleep disorders in children, alternative studies for diagnosing obstructive sleep apnea (OSA) may be considered if PSG is not available. These include nocturnal home audio or video recordings, nocturnal oximetry, daytime nap PSG, and home sleep apnea testing.

These approaches do not completely replicate results of PSG [12]. Nonetheless, the American Academy of Pediatrics (AAP) clinical practice guideline suggests ordering an alternative test (or referral to a sleep specialist or otolaryngologist) if PSG is not available, with the rationale that some objective testing is better than none [55]. The role of these tests in the evaluation of suspected OSA in children is reviewed separately. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Alternatives to polysomnography'.)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Sleep-related breathing disorders including obstructive sleep apnea in children" and "Society guideline links: Parasomnias, hypersomnias, and circadian rhythm disorders".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

Basics topics (see "Patient education: What is a sleep study? (The Basics)" and "Patient education: Daytime sleepiness (The Basics)" and "Patient education: Narcolepsy (The Basics)" and "Patient education: Night terrors, confusional arousals, and nightmares in children (The Basics)" and "Patient education: Restless legs syndrome (The Basics)" and "Patient education: Sleepwalking in children (The Basics)" and "Patient education: Sleep apnea in children (The Basics)")

SUMMARY

Comprehensive in-laboratory overnight polysomnography (PSG), also known as level 1 PSG, is the gold standard method for recording sleep/wake states and for diagnosing obstructive sleep apnea (OSA) and other selected sleep disorders in children. (See 'Types of sleep studies' above.)

The most common indication for PSG in children is a suspected diagnosis of OSA or other sleep-related breathing disorder (SRBD). In addition to its diagnostic role, PSG plays an important role in the titration of positive airway pressure (PAP) therapy for OSA and in the preoperative evaluation before upper airway surgery (eg, adenotonsillectomy). PSG is also indicated for the evaluation of atypical or potentially injurious parasomnias, and for suspected narcolepsy types 1 or 2 or other central disorders of hypersomnolence, in combination with a multiple sleep latency test (MSLT). (See 'Indications for polysomnography' above.)

PSG can be frightening for children. Adopting and routinely employing child-friendly, family-centered PSG practices can increase the likelihood of obtaining an interpretable PSG and the patient returning for follow-up. (See 'Child-friendly techniques' above.)

Sleep/wake states are scored in a PSG by recording electroencephalography (EEG), eye movements (electrooculography [EOG]), and submentalis (chin) surface electromyography (EMG). In addition, multiple sensors are applied to characterize ventilation and cardiac rhythms, including a snoring microphone, nasal pressure airflow, oronasal thermal sensors, respiratory impedance plethysmography, electrocardiogram (ECG, one or two leads), pulse oximetry, body position, and carbon dioxide monitoring. Surface EMG activity from the anterior tibialis muscles is routinely recorded to detect leg muscle activity and movements. (See 'Recorded signals' above.)

Following the recording, sleep/wake states and arousals are manually scored in 30-second sequential epochs. Respiratory events, periodic limb movements, paroxysmal motor behaviors, and other events are also scored, tabulated, and collated (table 1). The scored sleep study is then reviewed, revised where necessary, and interpreted by a sleep specialist. (See 'Scoring and interpretation' above.)

Level 1 PSG is a relatively safe procedure, although there are few systematic studies. The most common adverse events reported by pediatric sleep centers are falls out of a crib or bed, emphasizing the importance of fall awareness and other standard safety measures in the sleep laboratory. (See 'Safety considerations' above.)

Although in-laboratory PSG remains the preferred and appropriate study for the evaluation of both respiratory and nonrespiratory sleep disorders in children, the availability of PSG is limited in some regions, especially for infants and children. Alternative studies for detecting OSA may be considered if PSG is not available, recognizing that such studies do not precisely replicate results of full, in-laboratory PSG. (See "Evaluation of suspected obstructive sleep apnea in children", section on 'Alternatives to polysomnography'.)

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References