Sleep structure in sleep bruxism: A polysomnographic study including bruxism activity phenotypes across sleep stages.

The aim of the study was to assess sleep structure, phenotypes related to bruxism activity and basic respiratory parameters among a large group of participants with sleep bruxism and without obstructive sleep apnea. Adult participants with clinical suspicion of sleep bruxism and with no other significant medical history were recruited. Video-polysomnography was performed to detect masseter muscles activity. Polysomnographic scoring was performed according to the American Academy of Sleep Medicine Criteria. Finally, 146 participants were included. The participants were divided into three subgroups: severe, mild and no sleep bruxism. There were no differences in total sleep time, sleep latency, sleep efficiency, wake duration after sleep onset, rapid eye movement, and measured respiratory parameters. The severity of sleep bruxism contributed to the increased intensity of all sleep bruxism phenotypes in almost all sleep stages, apart from tonic and mixed activity in non-rapid eye movement stage 3 sleep (slow-wave sleep). Those with bruxism spent more time in rapid eye movement sleep compared to controls; there were no differences in non-rapid eye movement sleep stages. The results confirmed that sleep bruxism does not significantly affect sleep duration, efficiency and continuity (in terms of sleep-wake cycles). Sleep bruxism contributes to a higher percentage of rapid eye movement sleep in the total sleep time. Those with bruxism present more frequent episodes during all stages of sleep; however, in the case of slow-wave sleep, tonic and mixed activity observed in participants with sleep bruxism are comparable to those of healthy people.