In a sample without smokers, morbidly obese, or diabetic patients, AHI is the main predictor of CAD. SA should integrate the set of risk factors routinely assessed in clinical investigation for coronary disease risk stratification.

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Repeating the administration of the Epworth Sleepiness Scale in a clinical setting increases its score and diagnostic accuracy and correlation with SDB variables, without changing the psychometric properties of the scale. This experiment indicates the clinical usefulness of repeating the ESS. The scale can be repeated at a negligible cost, before dismissing individual patients on the basis of a low ESS score, discontinuing a potentially lifesaving diagnostic and therapeutic process.

In conclusion, simple questionnaire-based diagnostic tools can be included in the screening procedures of patients with angina to detect the need for further OSA evaluation. In conclusion, the BQ is an effective instrument for this purpose.

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Recently, Martinez-Lavin [1] proposed a model of sympathetically maintained neuropathic pain syndrome that has the merit of scrutinizing possible mechanisms behind the central sensitization model [2]. Eisinger [3], in an editorial comment, raises the issue of heterogeneity permeating Martinez-Lavin's proposition. Since it is difficult to establish a traumatic trigger event in all cases, Eisinger considers multicausality as more reasonable than a single post-traumatic etiology for all cases. Félix and Fontenele [4] further explored this venue, speculating that the orthostatic intolerance symptoms seen in the majority of fibromyalgia patients are a consequence of sympathetic hyperactivity. The idea that a COMT val-158-met polymorphism may cause higher cathecolamine levels has been explored [5]. Loevinger and colleagues [6] have shown that the metabolic syndrome is more common in individuals with fibromyalgia who also have higher body mass index, blood pressure, and waist-to-hip ratio than controls.Interestingly, elevated body mass index, blood pressure, and waist-to-hip ratio are associated with sleep-disordered breathing. We recently reported in a study that 50% of the women with obstructive sleep apnea syndrome or upper airway resistance syndrome had chronic pain and more than 11 tender points when pressed with 4 kgf/cm 2 [7]. Guilleminault and colleagues [8] reported orthostatic intolerance in patients with upper airway resistance syndrome. We believe that the authors investigating this theme should discuss the possibility of sleep-disordered breathing being the missing link between fibromyalgia, pain, disturbed sleep, alpha-delta sleep, hypotension, sympathetic hyperactivity, and metabolic syndrome.We are conducting investigations into whether exposition to the typical stress of sleep-disordered breathing -with repeated arousal episodes and hypoxemia -has fibromyalgia as a possible outcome. Our preliminary results underline the need to consider and further explore this hypothesis. Competing interestsThe authors declare that they have no competing interests.

Introduction: Seasonal affective disorder (SAD) is a proposed mental disorder still controversial. This condition is prevalent in northern latitudes, but few studies have been conducted at locations in the southern hemisphere. It is usually assessed by the Seasonal Pattern Assessment Questionnaire (SPAQ). This study aimed to evaluate, through on-line questionnaire, the hypothesis that, in the Brazilian population, latitude and longitude influence SPAQ scores. Methods: An advertisement was posted on a sleep medicine website inviting visitors to investigate seasonal patterns of behavior and mood, using a Brazilian Portuguese version of the SPAQ. The geographic coordinates of the place of residence of each respondent were analyzed as a continuous variable or distributed in quartiles of latitude and longitude. The psychometric properties of the SPAQ were assessed by reliability and factor analyses. Results: Answers from 1001 respondents out of 1045 were considered eligible. High SPAQ scores were observed in 287 respondents, equally distributed among all latitude and longitude quartiles. Data collected in different seasons and during daylight saving time did not differ significantly in any of the scores for SPAQ dimensions. No correlations between SPAQ scores and latitude or longitude were observed. Psychometric properties of the SPAQ were preserved in all geographic locations. Conclusion: The finding of similar SPAQ scores at a wide latitude range defies the concept of SAD symptoms as latitude or longitude-dependent phenomena.

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