Changes in heart rate related to rhythmic masticatory muscle activities and limb movements in patients with sleep bruxism.

Abstract

Most sleep bruxism (SB) episodes are accompanied by an increase in sympathetic tone and heart rate (HR). To characterise heart rate (HR) changes in relation to rhythmic masticatory muscle activities (RMMAs) in SB patients, polysomnographic recordings were performed on 10 SB patients and 11 normal controls. The duration of movement events, amplitude and duration of HR increases, and time to reach HR peak associated with RMMAs and limb movements (LMs) were determined, and the relationships of the parameters of HR increases with types of movements and RMMAs were analysed. All of the parameters of HR increases associated with three types of movements (RMMAs, RMMAs+LMs and LMs) and masseter activities (phasic, tonic and mixed) were significantly different (two-way ANOVA, P<.001 for all) in both SB patients and controls. The duration of RMMAs/LMs was positively correlated with the parameters (SB patients: R2 =.24-.85, P<.0001; controls: R2 =.23-.68, P<.0001). The amplitude of HR increases was also positively correlated with respiration changes in the SB patients (R2 =.3258, P<.0001) and controls (R2 =.09469, P<.05). The proportions of phasic RMMAs associated with awakenings, microarousals and no cortical arousals were significantly different and so were the proportions of tonic and mixed RMMAs (Friedman's tests, P<.05-.001). The HR increases associated with RMMAs may be intrinsic to the cortical arousal response and autonomic activation, and differences in HR increases associated with different types of movements and RMMAs might be related to the changes in respiration and differences in cortical arousal levels.