This case-control study will evaluates the association between the definitive sleep bruxism diagnosis by gold-standard polysomnography examination obtained at Pelotas Sleep Institute and the sociodemographic, occupational, clinical conditions, sleep quality, sleep structure and Epworth sleepiness scale variables.

Currently, as sleep and awake bruxism are generally considered as different behaviours observed during sleep and wakefulness, respectively, the single definition for bruxism is recommended be "retired" in favour of 2 separate definitions. In this sense, the sleep bruxism is a masticatory muscle activity during sleep that is characterised as rhythmic (phasic) or non-rhythmic (tonic) and is not a movement disorder or a sleep disorder in otherwise healthy individuals .The diagnosis of sleep bruxism often is challenging and despite the use of questionnaires, clinical exams and portable devices, based on current knowledge, the polysomnography with audio-video recordings emerges as the gold-standard criteria for a definite sleep bruxism diagnosis.

Included on the questionnaire there is a registration form, which contains: Sociodemographic: self-reported ethnicity, marital status, education level; Occupational: individuals were asked about work outside home, working hours; Clinical condition: body mass index, smoking; alcohol consumption; use of sleeping pills.

Sleep Quality, was evaluated with the following questions: Sleep behavioral, how long does it take to sleep; restless sleep; nightmares; heartburn, obstructive sleep apnea by polysomnography. Bedtime, sleep time. Waking during the night, insomnia. Morning wake up, headache on waking; Lastly, Sleep structure data: sleep onset latency, rapid eye movement, sleep latency, wake time after sleep onset, total sleep time, sleep efficiency, non-rapid eye movement, sleep time in stages N1, N2, and N3, REM sleep time, arousal, arousal per hour, respiratory disturbance index, apnea-hypopnea index; and Epworth Sleepiness Scale.

Inclusion Criteria:

• Adults (aged 20 to 60 years) and elderly (aged > 60 years) (WHO-World Health Organization, 2015) who were undergone to polysomnography (PSG) at the Pelotas Sleep Institute (PSI);
• Adequate cognitive capacity to understand and answer the questionnaire.

Exclusion Criteria:

• Those which the participants were unable to answer the questionnaires and who presented a history of epilepsy that could interfere in the results of PSG.

Individuals who are in the adult and elderly age group and who seek or are referred to the Pelotas Sleep Institute for polysomnography in the period from January 2015 to December 2017 were assessed.