['Low levels of sex hormones, especially progesterone, are suspected as a risk factor for sleep-disordered breathing (SDB).', 'To test the hypothesis that serum levels of progesterone, estradiol, and 17-OH progesterone are lower in those women with clinically significant SDB.', 'Clinical cohort of convenience.', 'University Hospital Sleep Laboratory.', 'We investigated sleep and breathing parameters and serum levels of sex hormones in 53 consecutive women (ages 24 to 72 years) being evaluated for symptoms of daytime sleepiness. Analysis of hormonal status by specific radioimmunoassays and fluorescence immunoassays was done from blood samples taken after an overnight polysomnography.', 'Across the cohort, taking account of age and cycle time or postmenopausal status, those with an apnea-hypopnea index (AHI) greater than 10/hrs of sleep had significantly lower levels of 17-OH progesterone, progesterone, and estradiol than those with an AHI less than 10.'] Do women with sleep apnea have lower levels of sex hormones?