Relationship between sleep bruxism and sleep respiratory events in patients with obstructive sleep apnea syndrome

Both obstructive sleep apnea syndrome (OSAS) and sleep bruxism (SB) are commonly related to arousal events. In this study, we examined the effect of SB on the sleep architecture and investigated the relationship between SB and sleep respiratory events in patients with OSAS. Patients with OSAS (n = 67) in whom apnea/hypopnea occurred five or more times per hour were recruited to this study. Healthy volunteers (n = 16) were recruited as controls. None of the healthy volunteers had any sleep disorders or medical disorders, nor had they taken any medication or alcohol. Data were collected by standard polysomnography during overnight sleep tests in a dark, quiet room. The frequency of SB was higher in the OSAS than in the control group. The risk of SB was significantly higher in the OSAS than in the control group (odds ratio, 3.96; 95 % confidence interval, 1.03-15.20; P < 0.05). Apnea/hypopnea and desaturation events occurred significantly more frequently in patients with than without SB. The frequency of the phasic type of SB correlated positively with that of obstructive apnea, micro-arousal, and oxygen desaturation. The frequency of SB events during micro-arousal events consequent on apnea/hypopnea events was significantly higher in the OSAS than in the control group. We found that patients with OSAS have a high risk of SB. In particular, this is the first report relating phasic-type SB to obstructive apnea events. This relationship suggests that improvement in OSAS might prevent exacerbations of SB.