Positive airway pressure (PAP) therapy is the gold standard treatment for obstructive sleep apnea (OSA), yet patients often express concern about its impact on sleep quality during the initial phase of treatment. This study investigated whether the first night of PAP therapy adversely affects objective sleep architecture. In this retrospective study, polysomnographic data from N = 176 patients with OSA undergoing first-night PAP therapy (continuous, auto titrated, or bilevel) were compared with a healthy sleep control group (N = 73). Sleep efficiency (SE), proportions of sleep stages (N1, N2, N3, and R), number of arousals, residual apnea-hypopnea index (AHI), and amount of AHI reduction were assessed. Group differences were examined using multivariate analyses of variance, and associations between age, residual AHI, and AHI reduction with SE were evaluated using correlation analyses. PAP therapy did not impair overall sleep architecture during the first night. N3 and R sleep were preserved across therapy modalities, with no significant differences compared to the healthy group. SE and stage N2 sleep were modestly reduced in the PAP groups. Across all groups, increasing age was associated with lower SE, indicating this effect was independent of PAP therapy. Residual AHI as well as AHI reduction were not associated with SE. During the first night of PAP therapy, N3 and REM sleep were comparable to those of healthy sleepers, whereas SE and N2 sleep were lower. These findings provide clinically reassuring evidence that the first supervised night of PAP therapy is compatible with largely preserved restorative sleep architecture, despite modest reductions in SE and N2 sleep.

Bruxism is an involuntary motor activity linked to periodontal changes, temporomandibular disorders, and tooth wear. Obstructive Sleep Apnea Syndrome (OSAS) involves recurrent upper airway obstruction during sleep and may be associated with bruxism and primary snoring. Understanding this relationship could improve diagnosis and clinical management. To assess systematic reviews to determine whether a bidirectional relationship exists between OSAS and bruxism in adults. An umbrella systematic review was conducted following PRISMA 2020. Systematic reviews with or without meta-analysis examining bruxism and OSAS in adults were included. Searches were conducted in PubMed, LILACS, BVS, SciELO, Scopus, and Embase for studies published from 2000 to January 2026, without language restrictions. Eligible studies used polysomnography-based diagnoses, met PECOT criteria, and were available in full text. Methodological quality and risk of bias were assessed with AMSTAR-2 and ROBIS. Two independent reviewers performed study selection. From 1726 records, eight systematic reviews were included, only one with a meta-analysis. Most reviews reported frequent coexistence of sleep bruxism and OSAS, possibly due to shared mechanisms like micro-arousals and autonomic activation, though causality remains unclear. Methodological quality was mostly low or critically low, and only three reviews had low risk of bias. Overall, evidence was heterogeneous and limited. Adults with OSAS appear more likely to experience sleep bruxism, indicating a potential bidirectional association. However, heterogeneity and low methodological quality limit the strength of evidence. Well-designed randomized and longitudinal studies are needed to clarify this relationship.