BACKGROUND: Electromyography (EMG) biofeedback (BF) training is potentially an effective cognitive-behavioural approach to regulate bruxism. OBJECTIVE: This study examined sleep bruxism regulation by daytime clenching control using a single-channel auditory EMG BF device. METHODS: Seventeen male subjects (mean age, 24.4 ± 3.1 years; mean ± SD) with self-reported awake/sleep bruxism were recruited and divided into a BF (n = 10) and a control (CO) group (n = 7). All subjects underwent four EMG recording sessions during both daytime and sleep over 3 weeks. During the daytime, in week 2, the BF group received feedback alert signals when excessive EMG activity with certain burst duration was detected while the subjects performed regular daily activities. The CO group underwent EMG recording sessions without receiving any alerts of parafunctional activity. The number of phasic burst events during sleep was compared between the BF and CO groups. RESULTS: While the number of phasic EMG events was not significantly different between the BF and CO groups at baseline, significantly smaller phasic events were observed in the BF compared to the CO group at the follow-up session (week 3) (P = .006, Tukey's HSD). Since daytime BF training is aimed at raising awareness of awake bruxism, it does not interrupt the sleep sequence or involve associated side effects. CONCLUSION: The present results suggest that EMG BF targeting for tonic EMG events during the daytime can be an effective method to regulate phasic EMG events during sleep.