Impaired respiratory and functional capacity in individuals with sleep BRUXISM: A controlled cross-sectional study

Growing evidence indicates that Sleep bruxism (SB) is recognized as a multifaceted condition that potentially has systemic implications, including effects on respiratory functions, exercise capacity, and possibly other body systems, which may reduce overall quality of life (QOL). This study aimed to investigate respiratory functions, respiratory muscle performance, functional capacity, and QOL in individuals with SB compared to healthy controls.

This study included 47 individuals with probable SB and 21 healthy controls. The classification of SB was based on self-reported and/or partner-confirmed sleep-related masticatory muscle activity (2018 international consensus criteria on bruxism). Respiratory functions were assessed via spirometry, respiratory muscle strength using maximal inspiratory and expiratory pressure measurements, and respiratory endurance with an incremental threshold loading test. Functional capacity was evaluated using the 6-min walk test (6MWT), and QOL was measured using the Short Form-36 questionnaire.

Compared to healthy controls, individuals with SB showed significantly lower peak expiratory flow (p < 0.001), maximal inspiratory and expiratory pressures (p < 0.001), and respiratory muscle endurance (p < 0.001). They also demonstrated reduced walking distance during the 6MWT and lower predicted percentage values (p < 0.05). Additionally, QOL scores were significantly lower in physical functioning, vitality, emotional wellbeing, and general health (p < 0.05).

This study highlights that probable SB may be associated with reduced respiratory muscle performance, diminished functional capacity, and lower QOL. These findings emphasize the importance of considering systemic evaluations, particularly of respiratory and physical function, in the clinical management of SB.