Temporomandibular disorder (TMD), a common cause of chronic orofacial pain, is a group of painful and/or dysfunctional conditions of the masticatory muscles, temporomandibular joint (TMJ) and associated structures.

The diagnostic questionnaires will be administered and the participants' responses will subsequently be analyzed, evaluating the presence of temporomandibular disorders (DTMs) in patients with sleep disorders.

The questionnaires will be administered to patients with a previous diagnosis of sleep disorder carried out at a specialist centre, consecutively belonging to the outpatient clinics of both centers U.O of Neurology-Sleep Disorders Center and U.O of Dentistry.

The main aim of the present study is to evaluate the prevalence of TMDs in patients with sleep disorders. This population was selected in order to contribute, in the context of scientific research, to the investigation into the association between temporomandibular disorders and sleep disorders, which include all those disorders that compromise both the quantity and quality of sleep with repercussions important on general health and quality of life, like:

• Insomnia
• Hypersomnia
• Restless legs syndrome
• REM sleep behavior disorder
• Narcolepsy
• Obstructive sleep apnea syndrome (OSAS)
• Primary snoring
• REM parasomnias (Sleepwalking, arousal disorders, excessive daytime sleepiness and night terrors)
• Nocturnal epilepsy Patients with sleep disorders may be recruited in the observational study conducted by the University's Department of Dentistry Vita-Salute San Raffaele and the Neurology-sleep disorders unit of the San Raffaele Hospital in Turro, aimed at evaluating the prevalence of T

Through this study we also want to evaluate the difference between the prevalence of TMDs in patients with sleep disorders and the prevalence of TMDs in non-patological population through the data present in the scientific literature.