BACKGROUND: The relationships between obstructive sleep apnea (OSA) and diverse types of pain disorders have been reported. However, the interaction between OSA and pain-related temporomandibular disorder (TMD) remains obscure. METHODS: A total of 60 adults (male/female, 48/12; mean age, 41.7 +/- 13.2 years) with pain-related TMD were enrolled. All participants underwent overnight full-channel polysomnography and had assessment of size and position of the tongue, tonsillar size, height, and weight. Diagnostic Criteria/TMD criteria was applied to diagnose TMD. Myofascial trigger points (TrPs) were bilaterally evaluated in the two masticatory and four cervical muscles including the temporalis, masseter, trapezius, sternocleidomastoid, occipitalis, and splenius capitis muscles. Participants were divided into three groups in accordance with their levels of OSA. RESULTS: The significantly higher number of active TrPs were detected in participants with severe OSA. The number of active TrPs in the masticatory muscles significantly interacted with diverse types of apneic and arousal indices. CONCLUSION: The myofascial pain modulating mechanisms and jaw function could have interactions with nocturnal hypoxia and sleep fragmentation in chronic pain-related TMD patients.