Comparison of the Occurrence of Sleep Bruxism under Accustomed Conditions at Home and under Polysomnography Conditions in a Sleep Laboratory

Purpose: We aimed to clarify the relationship between the number of sleep bruxism (SB) bursts at home and in a laboratory equipped with polysomnography with audio-video recording (PSG-AV). We applied an identical single-channel wearable electromyography (EMG) device for both types of SB burst scorings. Methods: The subjects were 20 healthy student volunteers (12 men and 8 women; mean age, 21.9 years) who were clinically diagnosed with bruxism based on the criteria set forth by the International Classification of Sleep Disorders (ICSD-2). We used a wearable EMG device attached to the masseteric area (the FLA-500-SD [FLA]), for scoring SB bursts at home and in the laboratory. PSG-AV was set within the laboratory environment as well. The mean interval for both sleep studies was 28.8 days. EMG bursts with amplitudes greater than twice the baseline amplitude and with durations of longer than 0.25 s were selected. EMG bursts with amplitudes >= 5% MVC (maximum voluntary contraction), >= 10% MVC, and >= 20% MVC were selected as well. A cluster of bursts was defined as an episode. Results: In all the conditions for selecting EMG bursts specified above, the number of SB bursts and episodes recorded under laboratory conditions was statistically significantly smaller than that recorded at home. There were no statistically significant differences between the data obtained on the first and second recording days. Conclusion: The results of this study suggest that the unfamiliar environment of a sleep laboratory equipped with PSG-AV affects the emergence of SB as compared with home conditions.