Table 2.

Clinical studies analyzing pathophysiological relationships between SB and SAHS.

Authors and Year	Type of Study	Objective	M&M	Parameters	Risk of Bias	Conclusions
Hosoya et al. 2014 [31]	CS	Linking SB, SAHS, and awakenings	PSG on 67 SAHS patients and 16 healthy patients (control group) for 1 night	Electroencephalogram, electrooculogram, electromyogram, respiratory flow, snoring, respiratory movements of the abdomen, saturation of oxygen, and electrocardiogram	Moderate (selection bias)	Patients with SAHS are at high risk of SB. This is the first report linking phasic type SB (eccentric) with obstructive apnea events. Improvement of SAHS could prevent exacerbation of SB.
Saito et al. 2016 [32]	CS	Linking apnea and bruxism	PSG and recording of 59 participants for 1 night	RMMA and awakenings	Moderate (attrition bias)	There is no association between RMMA and awakenings, most movements during apnea are non-rhythmic, and SAHS and SB are related by some type of mechanism.
Tan et al. 2019 [33]	Retrospective CS	Determine the prevalence of SB in patients with SAHS	PSG on 147 patients diagnosed with SB (SBI > 4) for 1 night	Micro-awakenings, DOI, AHI	High (selection bias)	One-third of the patients had both SB and SAHS. They presented more micro-arousals; therefore, RMMA may be related as a protective phenomenon against hypoxemia-related micro-arousals.
Smardz et al. 2020 [34]	CS	SB and SAHS relationship	77 patients with suspected SB undergoing PSG and EMG for 1 night	BEI, the type of RMMA, AHI and DOI	High (selection bias, performance bias)	Tonic contractions are related to SAHS events.
Suzuki et al. 2020 [35]	Retrospective CS	Relationship between SB and fluctuation of O2 and CO2	PSG and EMG for 1 night on 12 patients	RMMA, changes in O2 saturation, exhaled CO2, and apnea and hypopnea events	High (selection bias)	Before an RMMA, the O2 saturation drops, but this does not affect the CO2 expelled. The relationship between SAHS and SB is physiological.

M&M: materials and methods; CS: clinical study.