Breathing During Sleep in Menopause: A Randomized, Controlled, Crossover Trial With Estrogen Therapy

OBJECTIVE To evaluate the prevalence of different types of nocturnal breathing abnormalities in postmenopausal women and the effect of estrogen replacement therapy (ERT) on nocturnal breathing. METHODS A prospective, randomized, placebo-controlled, double-blind, crossover study was completed by 62 of 71 recruited healthy women. The first 3-month treatment period with either estrogen or placebo was followed by placebo washout for a month and then by a second treatment period with crossover to either estrogen or placebo. On a night after each treatment period, sleep was monitored with polysomnography, and breathing was assessed with a static-charge-sensitive bed and oximeter. For the respiratory variables, a sample size of 48 subjects was sufficient to give statistical power of 85% with a significance level of P < .05. RESULTS The occurrence of obstructive sleep apnea in all women was low (1.6%), but partial upper airway obstruction, manifesting as an increased respiratory resistance pattern, was more common (17.7%). Estrogen replacement therapy decreased the occurrence (P = .047) and frequency (P = .049) of sleep apnea but had no effect on partial upper airway obstruction or arterial oxyhemoglobin saturation. CONCLUSION Partial upper airway obstruction is the most prevalent form of sleep-disordered breathing, occurring ten times more frequently than sleep apnea in postmenopausal women. Unopposed estrogen replacement therapy has only a minor effect on sleep apnea and has no effect on partial airway obstruction.