Sleep, waking and sleep inertia in sexual assault: A retrospective descriptive study.

Women who wake from sleep during sexual assault commonly report confusion and disorientation. Confusion and disorientation, with impaired decision making after waking, are symptoms of 'sleep inertia', and part of the normal transition from sleep to full wakefulness which is maximal in the minutes after wakening and can be prolonged. In this study of 305 adult females (median age 26, range 18-68), who presented for a sexual assault forensic medical examination, 38 (12%) (median age 27, range 18-51) woke to find sexual acts already in progress.