Relationships between sleep-related bruxing, electroencephalog raphic phenomena, and other physiologic variables are reviwed. Bruxing occurs during all sleep stages but occurs disproportionately during stage 2 and REM. B ruxing during deeper sleep stages frequently is followed by a transition to lighter sleep. Bruxing occurs in conjunction with K-complexes in the EEG, tachycardia and peripheral blood volume changes, and gross body movements; however, the exact nature of the relationship between bruxing and arousal is unknown. Methodological problems are pervasive. On-line computer-based event recording is called for along with time series analyses of moment-to-moment psychophysiologic data.