Modulation of the sleep electroencephalogram by estrogen replacement in postmenopausal women

OBJECTIVE: We performed an examination of the effects of estrogen replaceme nt on the sleep electroencephalogram in postmenopausal women. STUDY DESIGN: A sleep electroencephalogram was recorded in 11 postmenopausa l women with and without estrogen administered by skin patch (50 mu g of es tradiol per day). RESULTS: Estrogen enhanced rapid-eye-movement sleep (50 +/- 4 vs 39 +/- 5 m inutes, 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 a nd delta activity from the first to the second cycle tin percentage from th e first cycle) was restored by estrogen (-56% +/- 9% vs -5% +/- 14% and -20 % +/- 6% vs -2% +/- 5%; P <.05, respectively). Sigma electroencephalographi c activity was increased by estrogen from the first to the second half of t he night but decreased during baseline. CONCLUSION: Estrogen treatment after menopause can help to restore the norm al sleep electroencephalogram pattern, which in turn might contribute to im proved cognitive functioning.