Handedness and sleep apnea.

Left-handedness is associated with shorter life span. Many of the factors contributing to this higher mortality (eg, alcohol consumption, automobile accident, smoking) are the same as in patients with sleep apnea, who also have higher mortality than nonapneic controls. The authors hypothesized that (1) there is a higher prevalence of sinistrality in patients suspected of having sleep apnea than in the general population, and (2) left-handed persons with sleep apnea have a more severe disorder than right-handed ones. These hypotheses were tested in a prospective cohort of 970 patients referred to a sleep disorders center because of suspected sleep apnea. All patients underwent nocturnal polysomnography and measurements of blood pressure. Sixty-one patients were left-handed. The distribution of handedness as a function of age in this cohort was similar to that in the general population. There were 486 patients with an apnea/hypopnea index greater than 10; of these, 34 were left-handed, and 452 were right-handed. Oxygen saturation, blood pressure, age, smoking history, and body mass index were similar in both groups. Left-handed patients with sleep apnea had a significantly higher respiratory disturbance index (RDI) than the right-handed ones (52 +/- 30 vs 38 +/- 35 [p < 0.005]). Right-handed patients were distributed equally among RDI quartiles, but 41 percent of the left-handed patients were within the highest RDI quartile, compared to 12 percent within the lowest quartile. Sinistrality appears to be associated with more severe sleep apnea, which may help to explain the higher mortality seen among the left-handed persons.