Recently published literature indicates that sleep disorders present with medical comorbidities quite frequently. The coexistence of a sleep disorder with a medical disorder has a substantial impact for both the patient and the health system. Insomnia and hypersomnia are highly comorbid with medical conditions, such as chronic pain and diabetes, as well as with various cardiovascular, respiratory, gastrointestinal, urinary and neurological disorders. Restless legs syndrome and periodic leg movement syndrome have been associated with iron deficiency, kidney disease, diabetes, and neurological, autoimmune, cardiovascular and respiratory disorders. Rapid eye movement behaviour disorder has been described as an early manifestation of serious central nervous system diseases; thus, close neurological monitoring of patients referring with this complaint is indicated. Identification and management of any sleep disorder in medical patients is important for optimizing the course and prognosis. Of equal importance is the search for undetected medical disorder in patients presenting with sleep disorders.

Thus far, the diagnosis of insomnia is based on purely clinical criteria. Although a broad range of altered physiological parameters has been identified in insomniacs, the evidence to establish the...

Objective:The aim of this study was to investigate the frequency of posterior semicircular canal benign paroxysmal positional vertigo in each ear, and to assess the association between the ear affected by benign paroxysmal positional vertigo and the head-lying side during sleep onset. Based on a previous study which used objective methods to prove the preference of the elderly for the right head-lying side during sleep, we hypothesised that a predominance of the same head-lying side in benign paroxysmal positional vertigo patients may affect the pathophysiology of otoconia displacement.Study design:We conducted a prospective study of out-patients with posterior semicircular canal benign paroxysmal positional vertigo, confirmed by a positive Dix–Hallpike test.Methods:One hundred and forty-two patients with posterior semicircular canal benign paroxysmal positional vertigo were interviewed about their past medical history, focusing on factors predisposing to benign paroxysmal positional vertigo. All patients included in the study were able to define a predominant, favourite head-lying side, right or left, during sleep onset.Results:The Dix–Hallpike test was found to be positive on the right side in 82 patients and positive on the left side in 54; six patients were found to be positive bilaterally. During sleep onset, 97 patients habitually laid their head on the right side and the remaining 45 laid their head on the left. The association between the affected ear and the head-lying side during sleep onset was statistically significant (p < 0.001).Conclusions:Our study found a predominance of right-sided benign paroxysmal positional vertigo, a subjective preference amongst patients for a right head-lying position during sleep onset, and an association between the ear affected by benign paroxysmal positional vertigo and the preferred head-lying side during sleep onset. The clinical and therapeutical implications of this observation are discussed.