During the normal NREM sleep phase, the basal tone of the upper airway muscles decreases, the caliber of the upper airway narrows, and the airway resistance increases, but the discharge phase of the upper airway muscles and the rhythmic contraction of the intercostal muscles remain intact. Diagnosis of upper airway trapping during inspiration: Chest pain during inspiration is one of the clinical manifestations of chest wall pain. 1, The pain is concentrated in only one point, which the patient can clearly point out. 2.The pain is not long lasting, usually lasting only one or two seconds each time, with a chance of recurrence. 3.When the patient breathes deeply, coughs, sneezes or turns around, the chest will stabbing pain or even severe pain. 4.The pain may be more intense than the chest pain caused by other diseases, but most of the pain resolves within a few days to two or three weeks. 5.It can occur at any age. The tone of the pharyngeal muscles is reduced, causing the upper airway to trap during inspiration. Hypotonia of the base of the chin-lingual muscle can cause posterior displacement of the tongue root and narrowing of the airway. Hypotonia of the intercostal muscles can cause chest wall instability during inspiration and produce paradoxical thoracoabdominal movements. In normal NREM sleep phase, the basal tone of upper airway muscles decreases, the caliber of upper airway decreases, and airway resistance increases, but the firing phase of upper airway muscles and the rhythmic contraction of intercostal muscles remain intact. during REM sleep, the basal tone of upper airway muscles, intercostal muscles, and most skeletal muscles are further suppressed. Reduced pharyngeal muscle tone can cause trapped closure of the upper airway during inspiration.