Modulation of the sleep electroencephalogram by estrogen replacement in postmenopausal women

Objective: We performed an examination of the effects of estrogen replacement on the sleep electroencephalogram in postmenopausal women. Study Design: A sleep electroencephalogram was recorded in 11 postmenopausal women with and without estrogen administered by skin patch (50 μg of estradiol per day). Results: Estrogen enhanced rapid-eye-movement sleep (50 ± 4 vs 39 ± 5 minutes, P < .05) and reduced time awake (12 ± 5 vs 20 ± 6 minutes, P < .05) during the first 2 sleep cycles. The normal decrease in slow-wave sleep and delta activity from the first to the second cycle (in percentage from the first cycle) was restored by estrogen (–56% ± 9% vs –5% ± 14% and –20% ± 6% vs –2% ± 5%; P < .05, respectively). Sigma electroencephalographic activity was increased by estrogen from the first to the second half of the night but decreased during baseline. Conclusion: Estrogen treatment after menopause can help to restore the normal sleep electroencephalogram pattern, which in turn might contribute to improved cognitive functioning. (Am J Obstet Gynecol 2000;182:277-82.)