The effects of hormone replacement therapy on sleep-disordered breathing in postmenopausal women: a pilot study

STUDY OBJECTIVES: To evaluate the impact of estrogen and estrogen plus progesterone hormone-replacement therapy (HRT) on mild-to-moderate sleep-disordered breathing (SDB) in postmenopausal women. DESIGN AND SETTING: Within-subjects, progesterone placebo-controlled prospective HRT trial in a clinical laboratory. PARTICIPANTS: Six postmenopausal women, diagnosed with mild-moderate SDB. INTERVENTION: Transdermal estradiol and oral micronized progesterone. MEASUREMENTS AND RESULTS: Subjects underwent polysomnography (PSG) on four occasions: a screening/adaptation night; a baseline night on no HRT; and two nights on HRT: one night after 7 to 12 days on estrogen plus placebo followed by a second night after 7-13 days on estrogen plus progesterone. The PSG was performed with a Sandman computerized PSG system using a standard clinical montage. Modified sleep diaries were used in the baseline week and throughout the study period. Mood was measured with the 20-item version of the Positive and Negalive Affect Schedule (PANAS). Estrogen monotherapy was associated with a significant reduction in the overall apnea-hypopnea index (AHI) (from a mean of 22.7 events per hour at baseline to a mean of 12.2 events per hour), but the AHI reduction on estradiol plus progesterone relative to baseline was not statistically significant (AHI=16.2 events per hour). Similar results were found for the percentages of total sleep time and of total non-rapid eye movement sleep time with oxygen saturation less than 90%. Estrogen, neither alone nor in combination with progesterone, significantly altered PSG- or diary-based measures of total sleep time, time to sleep onset, or time awake after sleep onset. CONCLUSIONS: While the data are preliminary and based on a small number of subjects, estrogen appeared to have a substantial beneficial effect on measures of SDB in postmenopausal women. Overall, no additional benefit was seen with the addition of progesterone. In fact, progesterone attenuated the beneficial effects of estrogen in 4 out of the 6 participants.