Overview of China’s Polysomnography Operation Guidelines and Clinical Applications

This article is sourced from: Chinese Medical Journal, 2018, 98(47): 3825-3831.

With the increasing understanding of sleep disorders in modern medicine, sleep monitoring technology has become more widely used in clinical departments such as neurology, respiratory medicine, otolaryngology, dentistry, and psychiatry. As an important tool in clinical sleep medicine and research, the value of polysomnography (PSG) technology is increasingly recognized. To further clarify the clinical indications for polysomnography in China, standardize operational procedures, unify diagnostic terminology and reporting formats, the Sleep Disorders Professional Committee of the Neurology Branch of the Chinese Medical Association, together with the Sleep Disorders Professional Committee of the Chinese Sleep Research Society and the Sleep Disorders Group of the Neurology Branch of the Chinese Medical Association, invited relevant experts from mainland China and Hong Kong to form the “Expert Committee on Polysomnography Operation Guidelines and Clinical Applications for Adults in China” to conduct in-depth discussions, appropriately referencing relevant foreign standards, and jointly drafting the “Expert Consensus on Polysomnography Operation Guidelines and Clinical Applications for Adults in China” after extensive consultation.

Overview

Polysomnography (PSG) is a diagnostic technique that continuously synchronizes the collection, recording, and analysis of multiple physiological parameters and pathological events during sleep using a polysomnograph in a sleep monitoring room. The parameters collected and recorded during polysomnography include electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), oral-nasal airflow, snoring, respiratory effort, pulse oximetry, body position, etc. Additional parameters such as video-audio monitoring, esophageal pressure, esophageal pH, transcutaneous or end-tidal carbon dioxide partial pressure, erectile function, etc., can also be added. These parameters are displayed in the form of curves, numbers, images, and video-audio, and form interpretable and analyzable data, known as polysomnograms. Polysomnography is a commonly used objective examination for analyzing sleep structure and assessing sleep disorders, and it is a fundamental tool in clinical sleep medicine and research.

(1) Indications for Polysomnography

1. Sleep-Related Breathing Disorders:

(1) Diagnosis of sleep-disordered breathing (SDB) patients, identifying the types of sleep apnea and hypoventilation events (obstructive/central/mixed) and the classification of sleep-disordered breathing (obstructive/central), assessing severity and differentiating from other sleep disorders; identifying sleep-related hypoventilation diseases and sleep-related hypoxic diseases; (2) Evaluating the effectiveness of various treatments for sleep-disordered breathing; (3) Re-examination of patients with high suspicion of sleep-disordered breathing but negative results from home sleep apnea monitoring or first polysomnography; (4) Re-evaluation of treatment in patients receiving non-invasive positive pressure ventilation who experience weight changes, poor clinical outcomes, or symptom recurrence; (5) Manual pressure titration prior to non-invasive positive pressure ventilation; (6) Clinical symptoms and signs suggesting possible sleep-disordered breathing, such as excessive daytime sleepiness not explained by primary disease, daytime hypoxemia, polycythemia, refractory hypertension, unexplained arrhythmias, nocturnal angina, morning dry mouth, or persistent chronic cough.

2. Excessive Daytime Sleepiness Disorders:

(1) Diagnosis, differential diagnosis, and treatment effectiveness evaluation of narcolepsy; (2) Diagnosis and differential diagnosis of idiopathic hypersomnia; (3) Polysomnography should be performed the night before multiple sleep latency testing (MSLT).

3. Parasomnias, Sleep-Related Epilepsy, and Other Nocturnal Events:

Identifying the types of nocturnal events such as parasomnias, sleep-related epilepsy, and muscle tone disorders. Particularly for patients with atypical clinical symptoms, unclear responses to conventional treatments, or those posing risks to themselves or others, polysomnography is necessary.

4. Sleep-Related Movement Disorders:

Diagnosis and evaluation of periodic limb movement disorder patients, and differentiation from restless legs syndrome, REM sleep behavior disorder, and other conditions.

5. Insomnia:

Primarily used for clinical evaluation of insomnia patients with atypical symptoms or poor treatment outcomes to determine the presence of subjective insomnia and to differentiate from other sleep disorders affecting sleep, such as sleep-disordered breathing, periodic limb movement disorder, and parasomnias.

6. Circadian Rhythm Sleep-Wake Disorders:

Determining the patient’s sleep structure and ruling out other sleep disorders. For observing circadian rhythm changes in patients, portable sleep monitoring technologies such as actigraphy are recommended.

7. Sleep Disorders Related to Mental Illness:

(1) Evaluating treatment effectiveness of sleep disorders related to mental illness; (2) Excluding other sleep disorders such as sleep-disordered breathing, restless legs syndrome, and medication-induced sleep disorders.

(2) Basic Principles and Recommendations for Polysomnography

1. When conducting polysomnography, it is essential to consider the significant differences in sleep habits among individuals, selecting appropriate recording start and end times according to the patient’s daily schedule. When interpreting polysomnography reports, clinical value should also be combined with the patient’s age and underlying diseases for individualized diagnostic analysis. Depending on the corresponding clinical examination needs of different departments, necessary specialized examinations of the patient should also be performed.

2. The interpretation of sleep staging and sleep-related events is recommended to follow the latest edition of the “AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications”.

Examination Methods and Procedures

(1) Content of Polysomnography Records and Electrode Placement

Polysomnography routinely records biological electrical signals such as EEG, EOG, EMG, and ECG; physiological signals such as respiratory airflow, chest and abdominal movement, pulse oximetry, and snoring; and external signals such as transcutaneous carbon dioxide and pressure titration-related parameters.

1. EEG electrodes should be placed according to the international “10-20” positioning system. The recommended combinations for EEG leads are C4-M1, F4-M1, and O2-M1; backup leads should use C3-M2, F3-M2, and O1-M2; acceptable leads include F_Z-C_Z, C_Z-O_Z, and C4-M1. Ground electrodes should be placed at or near Fpz, and reference electrodes should be placed at Cz. If electrodes malfunction during monitoring, backup electrodes should be placed at Fpz, C3, O1, and M2; substitutions can be made as follows: Fpz can replace Fz, C3 can replace Cz or C4, O1 can replace Oz, and M2 can replace M1.

2. EOG electrodes E1 and E2 should be placed 1 cm outward and downward from the outer canthus of the left eye and 1 cm outward and upward from the outer canthus of the right eye, respectively. EOG leads should be recorded using E1-M2/E2-M2.

3. The detection electrodes for the chin EMG should be placed 2 cm below the anterior edge of the mandible, 2 cm to the left of the midline for the Chin1 electrode, and 2 cm to the right of the midline for the Chin2 electrode. The reference electrode ChinZ should be placed 1 cm above the midline of the anterior edge of the mandible. Recommended leads are Chin1-ChinZ or Chin2-ChinZ.

4. For respiratory airflow monitoring: it is recommended to use both oral-nasal temperature sensors and nasal pressure sensors to monitor airflow. The oral-nasal temperature sensor is usually placed above the nostrils and lips.

5. For respiratory effort monitoring: it is recommended to use respiratory inductance plethysmography belts to monitor respiratory effort. The chest belt should be placed horizontally near the nipple and under the armpit, and the abdominal belt should be placed at the level of the navel. Intercostal/diaphragmatic EMG and esophageal pressure can also be recorded.

6. Pulse oximetry monitoring: typically, fingertip or earlobe sensors are used to continuously record pulse oxygen saturation to evaluate the degree and frequency of oxygen saturation reduction. The adult pulse oximeter probe is placed on the tip of the ring finger and securely fastened.

7. ECG monitoring: usually, single-lead ECG monitoring is applied. The modified lead II electrode placement method is recommended: the negative electrode is placed at the intersection of the right clavicle and the extended line of the right lower limb, and the positive electrode is placed at the intersection of the 6th and 7th intercostal spaces and the extended line of the left lower limb. This is mainly used to assess heart rate and arrhythmias.

8. Limb movement monitoring: electrodes are usually placed on the midsection of the anterior tibialis of both lower limbs, with a distance of 2-3 cm between the two electrodes. Depending on clinical examination needs, upper limb movements can also be monitored simultaneously, in which case electrodes should be placed on the midsection of the extensor or flexor muscles of both sides, with a distance of 2-3 cm between the two electrodes.

9. Video-audio recording: video and audio recordings should be synchronized with EEG, EOG, EMG, and other signals to confirm the patient’s position, abnormal behaviors, and vocalizations during sleep. Audio can also assist in diagnosing bruxism, sleep talking, snoring, groaning, etc. The snoring sensor should be placed at an appropriate position on the neck to capture the maximum signal.

10. Position recording: three-dimensional accelerometers for recording position changes are usually placed near the xiphoid process along the anterior midline, which can display different positions such as supine, prone, left lateral, right lateral, and upright.

11. Other auxiliary monitoring content: additional monitoring modules can be added based on different clinical examination needs. For patients with sleep-disordered breathing, additional monitoring of end-tidal carbon dioxide pressure and transcutaneous carbon dioxide pressure can be included. For parasomnia or epilepsy patients, full video EEG monitoring and additional EEG recording electrodes are recommended, with a 10 s window for analysis. For patients with gastroesophageal reflux disease, esophageal pH measurement can be performed simultaneously for diagnosis and treatment evaluation. For patients with erectile dysfunction, measuring penile rigidity can reflect the occurrence of erections, erection strength, and the sleep stage.

(2) Technical and Data Specifications for Polysomnography

1. Detection and recording of electrode impedance: electrode impedance should be detected and recorded before and after PSG recording. The electrode impedance for EEG, EOG, and chin EMG should be ≤5 kΩ, and for lower limb EMG, it is best to be ≤5 kΩ, ≤10 kΩ is also acceptable. If artifacts occur, the electrode impedance should be rechecked.

2. The minimum digital resolution should be 12 bits.

3. Sampling frequency and filtering: follow the recommended sampling frequency and filtering settings for each channel as per the “AASM Manual for the Scoring of Sleep and Associated Events: Rules, Terminology and Technical Specifications” (Table 1).

Table 1 Sampling Frequency and Filtering Settings for Each Channel in Routine Polysomnography Records (Hz)

Acquisition Parameters	Ideal Sampling Rate	Minimum Sampling Rate	Low-Frequency Filtering	High-Frequency Filtering
EEG Signal	500	200	0.3	35
EOG Signal	500	200	0.3	35
EMG Signal	500	200	10	100
ECG Signal	500	200	0.3	70
Oral-Nasal Temperature Airflow	100	25	0.1	15
Nasal Pressure Airflow	100	25	DC or ≤0.03	100
Positive Pressure Ventilation Airflow	100	25	DC	DC
Chest and Abdominal Movement	100	25	0.1	15
End-Tidal Carbon Dioxide	100	25	–	–
Pulse Oximetry	25	10	–	–
Transcutaneous Carbon Dioxide	25	10	–	–
Snoring	500	200	10	100
Position	1	1	–	–

(3) Procedures for Polysomnography

1. Mechanical Calibration: Before monitoring, the sensitivity, polarity, and filtering settings of each amplifier should be calibrated; appropriate signal sampling frequencies should be selected for different leads; and the display should be set to an appropriate resolution. Currently, digital PSG applications do not require mechanical calibration for each monitoring session, only periodic calibration is necessary.

2. Electrode Placement: After accurately measuring and positioning according to the aforementioned electrode placement requirements, the electrodes should be sequentially attached.

3. Biological Calibration: Standardized biological calibration is a necessary part of every sleep monitoring session. By observing the monitored individual performing corresponding actions as instructed, signals can be collected to record basic physiological parameters such as alpha rhythm in EEG recordings and amplitude of anterior tibialis EMG activity, and to determine whether the electrode placement is accurate, and whether the monitoring equipment, sensors, and electrodes are functioning normally. These instructed actions include closing eyes, opening eyes, moving eyes in various directions, inhaling, exhaling, holding breath, and moving toes (Table 2). Biological calibration should be performed before and after monitoring.

Table 2 Instructions and Observations for Biological Calibration

Number	Observation Channel	Instructions and Actions	Observed Effects
1	EEG Signal, EOG Signal	Supine, relaxed, quiet, eyes closed for 30 s	EEG leads show alpha rhythm activity in most individuals, EOG leads may show slow eye movements
2	EEG Signal, EOG Signal	Supine, relaxed, eyes open, looking straight ahead for 30 s	EEG leads show a decrease or disappearance of alpha rhythm activity, appearance of beta rhythm, EOG leads show rapid eye movements and blinking
3	EOG Signal	Keep head position unchanged, look up and down 5 times, look left and right 5 times	EOG leads show phase shifts, with larger amplitudes in horizontal eye movements than in vertical movements
4	EOG Signal	Keep head position unchanged, blink slowly 5 times	EOG leads show blinking
5	Chin EMG Signal	Clench teeth 3 times	Chin EMG leads show increased amplitude
6	Snoring Signal	Simulate snoring or make a sound for 5 s	Snoring channel shows increased amplitude
7	Oral-Nasal Airflow, Chest and Abdominal Breathing	Normal breathing for 5 s	Airflow and chest-abdominal breathing channels show synchronized signals
8	Oral-Nasal Airflow, Chest and Abdominal Breathing	Hold breath for 10 s, then breathe normally	Temperature, pressure, chest and abdominal breathing channels show reduced amplitudes approaching a straight line
9	Oral-Nasal Airflow	Only breathe through the nose for 10 s	Pressure and temperature sensor channels show airflow
10	Oral-Nasal Airflow	Only breathe through the mouth for 10 s	Pressure sensor channel shows disappearance of airflow
11	Lower Limb EMG Signal	Relax left foot, then right foot. Repeat 5 times.	Anterior tibialis EMG leads show increased amplitude
12	Position	Turn to the left side, maintain for 5 s; then turn to the right side, maintain for 5 s; then relax and lie flat	Position channel shows corresponding changes

4. After obtaining stable waveforms, monitoring should begin. During monitoring, observe the patient for abnormal behavior, actions, and events, promptly identifying and correcting potential signal artifacts, and regularly check impedance.

5. If the patient requests to get up or end the recording, monitoring should be paused or terminated.

6. Analyze the examination results, issue a signed report, and have the physician responsible for the sleep examination review and sign it.

Basis and Basic Rules for Sleep Staging

(1) Basis for Sleep Staging

Polysomnography mainly relies on information recorded from EEG, EOG, and chin EMG to comprehensively assess wakefulness and each sleep stage.

1. Common waveforms recorded by EEG:

Identifying EEG waveforms is a crucial basis for sleep staging. In addition to common waveforms such as alpha waves, beta waves, and delta waves in routine EEG monitoring, there are specific EEG waveforms that serve as primary references for interpreting corresponding sleep stages, including alpha rhythm, low-amplitude mixed frequency waves, vertex waves, sleep spindles, K-complex waves, slow waves, and sawtooth waves (Table 3).

Table 3 Common Waveform Characteristics and Physiological Significance of EEG Recordings in PSG

Name	Characteristics	Physiological Significance
Alpha Wave	Frequency: 8-13 Hz	Mainly seen in W stage, during quiet eyes closed
Alpha Rhythm	Sequence of sinusoidal EEG waves at 8-13 Hz	Mainly seen in W stage, during quiet eyes closed, and amplitude decreases when eyes are open, especially prominent in occipital leads
Beta Wave	Low-amplitude waves with frequency >13 Hz	Mainly seen in W stage when eyes are open
Slow Wave	Frequency: 0.5-2 Hz, frontal leads with amplitude >75 μV	Seen in N3 stage, with maximum amplitude in frontal leads
Theta Wave	Frequency: 4-7.99 Hz	Seen in N1, N2, and R stages
Low-Amplitude Mixed Frequency Wave	Continuous waves with amplitude <10 μV or single waves with amplitude <20 μV, frequency: 4-7 Hz	Seen in N1, N2, and R stages
Vertex Wave	Sharp waveform, duration <0.5 s	Maximum amplitude seen in central leads
Sleep Spindle	Frequency: 11-16 Hz, most commonly 12-14 Hz, duration ≥0.5 s	Characteristic wave of N2 sleep, maximum amplitude in central leads
K-Complex Wave	Composed of a clearly visible steep negative wave followed by a positive wave, duration ≥0.5 s	Characteristic wave of N2 sleep, usually with maximum amplitude in frontal leads
Sawtooth Wave	Frequency: 2-6 Hz, morphology resembling continuous sharp or triangular waveforms, similar to saw teeth	Usually appears before rapid eye movement, with maximum amplitude in central leads

Note:W stage: wakefulness; N1 stage: non-rapid eye movement sleep stage 1; N2 stage: non-rapid eye movement sleep stage 2; N3 stage: non-rapid eye movement sleep stage 3; R stage: rapid eye movement sleep stage.

2. Common waveforms recorded by EOG:

(1) Blinks: conjugate vertical eye movement waves appearing during blinking in the wakeful state, with a frequency of 0.5-2.0 Hz. (2) Reading Eye Movements: conjugate eye movements consisting of slow eye movements and subsequent rapid eye movements when reading text. (3) Rapid Eye Movements (REM): conjugate, irregular, and steep waveform eye movements, with initial peak time <500 ms. Rapid eye movements are characteristic of R stage and are also seen when the eyes are open scanning the surroundings. (4) Slow Eye Movements (SEM): conjugate, relatively regular sinusoidal eye movement waves, with initial peak time usually >500 ms.

3. Common waveforms recorded by chin EMG:

Chin EMG amplitude is usually higher during wakefulness than during sleep. After entering sleep, chin EMG amplitude gradually decreases from N1 to N3, and may already be at a lower level in N1, reaching the lowest level during R stage.

(2) Basic Rules for Sleep Staging

1. Basic Unit of Sleep Staging:

A continuous 30 s PSG recording is called an epoch. An epoch is the smallest unit of sleep staging, and each epoch should be marked as a sleep stage. When two or more sleep stages are present in one epoch, the dominant (most prevalent) sleep stage should be marked for that epoch.

2. Marking of Sleep Stages:

Normal sleep structure is divided into three parts: non-rapid eye movement sleep (NREM), rapid eye movement sleep (REM), and wakefulness, with NREM further divided into N1, N2, and N3 stages. (1) W stage: EEG can show low-amplitude mixed waveforms (beta and alpha waves) when eyes are open, and alpha rhythm can be recorded in occipital leads when eyes are closed, occupying >50% of the epoch. EOG can show reading eye movements, rapid eye movements, and blinks when eyes are open, and slow eye movements can be recorded when eyes are closed. Chin EMG amplitude is variable but generally higher than during sleep. (2) N1 stage: EEG features low-amplitude mixed frequency waves, occupying >50% of the epoch, and may show vertex waves. EOG can show slow eye movements. Chin EMG amplitude is variable, usually lower than during wakefulness. (3) N2 stage: EEG characteristic waves are sleep spindles and K-complex waves. EOG recordings usually show no significant eye movements, and slow eye movements may be observed. Chin EMG amplitude is variable, usually lower than during wakefulness. (4) N3 stage: Slow waves occupy ≥20% of the epoch in EEG. EOG recordings usually show no eye movements. Chin EMG amplitude is variable, usually lower than N2 stage, sometimes approaching R stage levels. (5) R stage: EEG shows low-amplitude mixed frequency waves, and sawtooth waves may appear. EOG shows rapid eye movements. Chin EMG shows a significant reduction in tone, usually at the lowest level of the entire recording.

3. Other Situations in Sleep Staging:

(1) Major Movement (MBM): When body movements and EMG artifacts interfere with EEG for more than 50% of an epoch, accurate sleep staging cannot be determined. (2) Arousal: A sudden change in EEG frequency during sleep causes a transient interruption in sleep continuity but does not necessarily indicate wakefulness. In NREM sleep, arousal requires observation of a sudden change in EEG frequency, with the appearance of alpha waves, theta waves, or frequencies >16 Hz, lasting ≥3 s, with a stable sleep period of ≥10 s before the frequency change. In REM sleep, arousal requires simultaneous observation of increased muscle tone in chin EMG for >1 s along with the EEG frequency change.

Sleep Stage Abnormal Events

(1) Respiratory-Related Events

1. Apnea:

The amplitude of the airflow signal in the oral-nasal temperature sensor channel decreases by ≥90% compared to baseline, and the event lasts ≥10 s. Based on whether there is respiratory effort during the airflow absence, it is further divided into: (1) Obstructive Apnea: respiratory effort persists or increases during airflow absence; (2) Central Apnea: respiratory effort disappears during airflow absence; (3) Mixed Apnea: during airflow absence, the initial part shows loss of respiratory effort, followed by recovery of respiratory effort.

2. Decrease in Pulse Oxygen Saturation:

Usually defined as an event where the pulse oxygen saturation decreases by ≥3% compared to before the respiratory event.

3. Hypoventilation:

The amplitude of the airflow signal in the nasal pressure channel decreases by ≥30% compared to baseline, the event lasts ≥10 s, and is accompanied by a decrease in pulse oxygen saturation by ≥3% or arousal.

4. Respiratory Effort-Related Arousal (RERA):

A respiratory event lasting ≥10 s characterized by increased respiratory effort or a flattened nasal pressure waveform, leading to arousal during sleep, but does not meet the criteria for apnea or hypoventilation.

(2) Cardiac-Related Events

1. Sinus Tachycardia:

Sinus rhythm during sleep, with a heart rate sustained at ≥90 beats/min for more than 30 s.

2. Sinus Bradycardia:

Sinus rhythm during sleep, with a heart rate sustained at ≤40 beats/min for more than 30 s.

3. Cardiac Arrest:

Cardiac arrest lasting ≥3 s.

4. Wide Complex Tachycardia:

At least three consecutive heartbeats with wide QRS complex waveforms, duration ≥120 ms, heart rate >100 beats/min.

5. Narrow Complex Tachycardia:

At least three consecutive heartbeats with QRS complex duration <120 ms, heart rate >100 beats/min.

6. Atrial Fibrillation:

Irregular heart rhythm, with normal P waves replaced by rapid fibrillation waves of varying sizes, shapes, and durations.

(3) Limb Movement Abnormal Events

1. Significant Limb Movements:

Lasting 0.5-10 s, EMG amplitude increases by >8 μV compared to resting state, with duration starting from the point of increased EMG amplitude and ending where it returns to ≤2 μV compared to resting state.

2. Periodic Limb Movements:

Four or more consecutive limb movements, with intervals of 5-90 s between two consecutive movements.

3. Periodic Limb Movements in Sleep (PLMS):

Periodic limb movements occurring during sleep.

4. Sustained EMG Activity During REM Sleep:

In one epoch of R stage, muscle activity in chin EMG exceeds the minimum amplitude during NREM sleep for >50% of the time.

5. Paroxysmal EMG Activity During REM Sleep:

In one epoch of R stage, subdivided into small epochs of 3 seconds, with >5 small epochs showing paroxysmal EMG activity lasting 0.1-5.0 s, with amplitude >4 times that of baseline EMG.

Content and Format of Report Writing

(1) Routine Report Content for Polysomnography

1. General Information of the Patient:

Including name, gender, contact information, height, weight, blood pressure, body mass index (BMI), neck circumference, waist circumference, etc.

2. General Information of the Examination:

Including the date of examination, purpose of examination, electrode placement method, recorded parameters, basis for sleep staging and related event interpretation, signatures of polysomnography analysis technician and physician, etc.

3. Sleep Structure Parameters:

(1) Light Out Time (hh:mm): The start time of sleep monitoring. The time when the lights are turned off and the patient is instructed to begin sleeping, usually consistent with the patient’s habitual sleep onset time. (2) Light On Time (hh:mm): The end time of sleep monitoring. The time when the patient is awake and indicates no longer sleeping. (3) Total Recording Time (TRT) (minutes): The duration from light out to light on, representing the total length of the sleep record. (4) Sleep Latency (SL) (minutes): The time from light out to the appearance of the first epoch of sleep. (5) Total Sleep Time (TST) (minutes): The total actual sleep time from light out to light on, i.e., the sum of the durations of each sleep stage (N1, N2, N3, R). (6) Wake After Sleep Onset (WASO) (minutes): The total time of all awakenings between the first epoch of sleep and the end of the recording. (7) REM Latency (minutes): The time from the first epoch of sleep to the appearance of the first epoch of REM sleep. (8) Sleep Efficiency (SE) (%): Total sleep time/total recording time × 100%. (9) Wake Time (W) (minutes): The total time of all wake periods during the recording, including sleep latency and wake time after sleep onset. (10) Time in Each Sleep Stage (minutes): The cumulative time in each sleep stage (N1, N2, N3, R). (11) Proportion of Each Sleep Stage (%): The percentage of cumulative time in each sleep stage (N1, N2, N3, R) relative to total sleep time. (12) Number of Awakenings: The total number of awakenings during sleep. (13) Arousal Index (ArI) (times/hour): The number of awakenings per unit sleep time, i.e., the total number of awakenings/total sleep time.

4. EEG Recordings:

Describing basic brain wave activity, whether abnormal brain activity exists, etc. If abnormal brain activity is detected during monitoring, it should describe the sleep stage in which it occurs, whether any abnormal seizure symptoms were observed, duration, and whether there are changes in autonomic nervous function related to heart rhythm and breathing.

5. Parameters Related to Respiratory Events:

(1) Number of Sleep-Related Breathing Events: The total number of apneas, hypoventilation, and RERA occurrences during sleep. (2) Number of Sleep Apnea and Hypoventilation Events: The total number of apneas and hypoventilation occurrences during sleep. (3) Number of Sleep Apneas: The total number of apneas during sleep. This needs to be further divided into obstructive, central, and mixed apneas. (4) Number of Hypoventilation Events: The total number of hypoventilation occurrences during sleep. (5) Sleep-Related Breathing Event Index (times/hour): The number of breathing events per unit sleep time, i.e., the total number of apneas, hypoventilation, and RERA occurrences/total sleep time. (6) Longest Duration of Apnea and Hypoventilation. (7) Oxygen Desaturation Index (ODI) (times/hour): The number of oxygen desaturation events per unit sleep time, i.e., the total number of desaturation occurrences/total sleep time. (8) Average and Lowest Oxygen Saturation. (9) Cumulative Time with Oxygen Saturation Below 88% or 90%.

6. Parameters Related to Cardiac Events:

Changes in heart rate during wakefulness and sleep (fastest heart rate, slowest heart rate, average heart rate), whether there are arrhythmia events, etc. If tachycardia exists, the fastest heart rate during the event should be described; if bradycardia exists, the slowest heart rate during the event should be described; for cardiac arrest, the longest duration of arrest should be described; for atrial fibrillation, the average heart rate should be described.

7. Abnormal Limb Movement Events:

(1) The number and index of periodic limb movements during sleep. (2) The number and index of arousal-related periodic limb movements.

8. Trend Graphs:

Using structured graphs to display sleep stages, arousals, breathing events, pulse oxygen saturation, and limb movement events during different monitoring periods.

9. Descriptions by On-Duty Technicians and Analysis Technicians of the Examination Process:

Including the patient’s cooperation during the examination, any abnormal activities observed during the night and related interventions, changes in the examination environment and equipment status, quality of polysomnography, and any special polysomnography presentations.

10. Diagnostic Summary:

Describing overall sleep conditions (sleep time, sleep structure), sleep-related breathing events and severity, abnormal behaviors during sleep stages, and limb movement events.

(2) Safety and Precautions for Polysomnography

Physicians in the sleep monitoring room should arrange medical staff for overnight monitoring based on the examination purpose and specific patient condition assessments. For special patients, informed consent should be signed if necessary, and family members should accompany them. Emergency plans should be developed for potential unexpected situations during monitoring, and sleep physicians and technicians should enhance personnel training to independently handle emergencies. The sleep monitoring room should have a relatively independent space, ensuring a quiet, dark, and comfortable sleep environment, controllable room temperature, and equipped with basic rescue equipment and protective devices.

Committee Members

Lead Author: Li Yanpeng (Department of Neurology, Changhai Hospital, Naval Medical University); Wang Waner (Sleep Center, Peking University International Hospital); Zhao Zhongxin (Department of Neurology, Changhai Hospital, Naval Medical University)

Members of the Expert Consensus Writing Committee (arranged by surname): Chen Guihai (Department of Neurology, Affiliated Chaohu Hospital, Anhui Medical University); Chen Kui (Department of Neurology, Peking University Affiliated Beijing Friendship Hospital); Deng Liying (Department of Neurology, Second Affiliated Hospital of Nanchang University); Fan Yuhua (Department of Neurology, First Affiliated Hospital of Sun Yat-sen University); Gao Dong (Sleep Center, Daping Hospital, Army Medical University); Han Fang (Department of Respiratory and Critical Care Medicine, Peking University People’s Hospital); Han Yanbing (Department of Neurology, First Affiliated Hospital of Kunming Medical University); He Guohua (Department of Psychiatry, Faculty of Medicine, Chinese University of Hong Kong); Hou Qian (Department of Neurology, People’s Hospital of Qinghai Province); Huang Yan (Department of Neurology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences); Li Qingyun (Department of Respiratory Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine); Li Yanpeng (Department of Neurology, Changhai Hospital, Naval Medical University); Liao Yuangao (Department of Neurology, First People’s Hospital of Chenzhou); Lin Hai (Department of Cerebrovascular Diseases, Xi’an Traditional Chinese Medicine Hospital); Lin Yongzhong (Department of Neurology, Second Affiliated Hospital of Dalian Medical University); Liu Chunfeng (Department of Neurology, Second Affiliated Hospital of Suzhou University); Liu Chunhong (Department of Neurology, General Hospital of Ningxia Medical University); Liu Ling (Department of Neurology, West China Hospital, Sichuan University); Liu Zhenhua (Department of Neurology, Provincial Hospital Affiliated to Shandong University); Long Xiaoyan (Department of Neurology, Xiangya Hospital, Central South University); Lu Xiaofeng (Department of Oral and Maxillofacial Surgery, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine); Ma Jianfang (Department of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine); Mao Chengjie (Department of Neurology, Second Affiliated Hospital of Suzhou University); Pan Jiyang (Department of Psychiatry, First Affiliated Hospital of Jinan University); Pan Yujun (Department of Neurology, First Affiliated Hospital of Harbin Medical University); Shang Wei (Department of Neurology, Second Hospital of Shandong University); Shao Hongyuan (Department of Neurology, People’s Hospital of Shanxi Province); Song Guoying (Editorial Office of Chinese Medical Journal); Tang Jiyou (Department of Neurology, Qianfoshan Hospital, Shandong University); Tang Xiangdong (Sleep Medicine Center, West China Hospital, Sichuan University); Wang Waner (Sleep Center, Peking University International Hospital); Wang Jie (Department of Neurology, First Hospital of Shanxi Medical University); Wang Weiwen (Department of Neurology, General Hospital of Chengdu Military Region); Wang Xiaoyun (Department of Neurology, Nanjing Drum Tower Hospital); Wang Yuping (Department of Neurology, Xuanwu Hospital, Capital Medical University); Wang Zan (Department of Neurology, First Hospital of Jilin University); Wu Huijuan (Department of Neurology, Changhai Hospital, Naval Medical University); Wu Yuncheng (Department of Neurology, First People’s Hospital of Shanghai); Wu Zhongliang (Department of Neurology, Xijing Hospital, Air Force Medical University); Xiong Yingqiong (Department of Neurology, People’s Hospital of Jiangxi Province); Su Zhangjun (Department of Neurology, Tangdu Hospital, Air Force Medical University); Xue Rong (Department of Neurology, General Hospital of Tianjin Medical University); Ye Jingying (Department of Otolaryngology, Tsinghua Changgung Hospital, Beijing); Yin Mei (Department of Neurology, Second Affiliated Hospital of Kunming Medical University); Yin You (Department of Neurology, Changhai Hospital, Naval Medical University); Yu Huan (Department of Neurology, Huashan Hospital, Fudan University); Zhan Shuqin (Department of Neurology, Xuanwu Hospital, Capital Medical University); Zhang Bin (Department of Psychiatry, Southern Medical University Southern Hospital); Zhang Hongju (Department of Neurology, People’s Hospital of Zhengzhou University); Zhang Peng (Department of Neurology, 91st Hospital of the PLA); Zhang Yan (Department of Neurology, Third Hospital of Peking University); Zhang Yifan (Department of Neurology, Affiliated Hospital of Guizhou Medical University); Zhang Zhiqiang (Department of Neurology, General Hospital of Lanzhou Military Region); Zhao Zhongxin (Department of Neurology, Changhai Hospital, Naval Medical University); Zhou Xiaohong (Department of Neurology, People’s Hospital of Guangdong Province)