References1. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S. The occurrence of sleep-disordered breathing among middleaged adults. N Engl J Med. 1993;328:1230---5, http://dx.doi.org/ 10.1056/NEJM199304293281704. 2. Bixler EO, Vgontzas AN, Lin HM, Ten Have T, Rein J, Vela-Bueno A, et al. Prevalence of sleep-disordered breathing in women: effects of gender. Am J Respir Crit Care Med. 2001;163 3 Pt 1:608---13, http://dx.