Effect of 17α-ethinyl estradiol on active phase rapid eye movement sleep microarchitecture

Estrogen treatment decreases active phase rapid eye movement (REM) sleep in ovariectomized rats. Here we explored further the effect of 17α-ethinyl estradiol (17α-EE) on active phase REM sleep in ovariectomized rats by analyzing spectral properties and the number and length of REM sleep bouts. The greatest suppression of REM sleep occurred on day 4 of 17α-EE treatment, was due to decreases in bout length, and was accompanied by decreased EEG theta power. These results further elucidate 17α-EE's effects on REM sleep and provide greater understanding of the mechanisms by which estrogens alter sleep–wakefulness patterns.