Effect of Daytime EMG Biofeedback Training on EEG during Sleep

Objectives: Sleep bruxism (SB) is well-known as one of the sleep disorders. Daytime electromyogram (EMG) biofeedback (BF) training aimed to regulate awake bruxism (AB) was found to be also effective to reduce SB in previous study. This study hence, aimed to investigate effect of daytime EMG-BF training on sleep electroencephalogram (EEG).
Methods: Eight male subjects (age: 22.6 ± 0.7 years) were recruited for this study. All subjects were diagnosed having SB according to ICSD - 2 criteria and also verified their SB status via polysomnogram (PSG) recording for 1 night before actual experiment. Subjects were randomly divided into BF group (n = 4) or control (CO) group (n = 4). EMG recordings with a portable device and PSG were undertaken for 5 hours in daytime and during sleep, respectively. Subjects in both groups were recorded their EMGs 4 days in consecutive 3 weeks. Although BF group recognized their EMG activities exceeding defined threshold in week 2, no BF signal was received in week 1 and 3, nor CO group throughout the recording period. EEGs were recorded during sleep for both groups. Power spectra of EEG delta band (0.50 - 4.00 Hz) and alpha band (8.00 - 13.00 Hz) were analyzed by fast Fourier transform.
Results: In BF group, all of the subjects showed alpha band power decreased (79.7-81.1%) and delta band power increased significantly in week 2 (104.4%) and 3 (104.5%) compared with those in week 1 (p<0.05, Tukey), while there was no specific change found in CO group.
Conclusions: With limitation of study design, it can be concluded that daytime EMG-BF training may help to improve quality of sleep.