The association between sleep bruxism and awake bruxism: Polysomnographic and electromyographic recordings in women with and without myofascial pain

BackgroundSleep bruxism (SB) and awake bruxism (AB) are masticatory muscle activities that are rarely assessed in the same individuals and are thought to be associated with different behaviours. ObjectivesTo investigate whether individuals engaging in SB also engage in AB, that occurs during rest and during stress-related activity, and to investigate whether SB and AB are associated with different characteristics. MethodsFemales with myofascial pain (N = 122) and non-myofascial pain controls (N = 46) were evaluated for SB events and for AB events at rest and AB during stress-related activity, using electromyographic (EMG) recordings and a standardised scoring of bruxism events. The joint distributions between SB and AB events and EMG activity were evaluated, and the characteristic qualities of SB and AB were assessed. ResultsNeither SB event rates nor the EMG activity associated with those events was associated with AB events rates or EMG activity, either at rest or during stress-related activity. On the contrary, event rates and EMG activity when awake and at rest were positively associated with events and activity during stress-related activity. SB was characterised mainly by grinding, while AB was characterised mainly by clenching. ConclusionSleep bruxism and awake bruxism do not tend to occur in the same individuals.