What inspired Charlotte Perkins Gilman to write the yellow wallpaper?

It's the moment the woman narrator takes complete leave of her sense. To be precise, it's when her husband comes in and she's creeping round and round the wall. She says, "I've got out, in spite of you and Jane." Her husband faints, and she continues to creep over him, to longer recognizing his connection to herself. All of this happens on the last page, basically the same as the ending.