Effects of estrogen replacement therapy on rates of cyclic alternating patterns and hot-flush events during sleep in postmenopausal women: A pilot study

The objective of this pilot study was to evaluate the effects of conjugated estrogens on the rates of cyclic alternating patterns of sleep (CAPS) and nocturnal hot flushes in symptomatic postmenopausal women. Seven postmenopausal or post-hysterectomy women aged 45 to 60 years with nocturnal diaphoresis and/or hot flushes participated in this study. The study was conducted with a single-masked design using a matching placebo. The placebo baseline was followed by a 4-week, single-masked treatment of conjugated estrogens 0.625 mg taken 4 hours before bedtime. Each patient's sleep was monitored in the laboratory for 3 consecutive nights during placebo baseline and again for 3 consecutive nights after an at-home period of at least 24 days of estrogen replacement therapy. Estrogen therapy resulted in a statistically significant decrease in the overall number of hot flushes and the number of hot flushes associated with awakenings, as well as improvement in sleep efficiency and a reduction in the rate of CAPS. These data confirm earlier well-established reports that estrogens reduce the frequency of hot flushes and suggest that the frequency of nocturnal arousals decreases and sleep quality improves in conjunction with a reduction in the rate of CAPS.