For the last few months I've noticed that my (almost) six-year-old daughter has developed somehwhat of a nightime routine. After she changes into her pajamas at night, she will usually lie down on the floor somewhere, ball up her blanket and put under her groin. She will lie on top of it and look like she goes into a humping motion. Sometimes this only lasts a minute, sometimes more and will often end her with her getting read-faced, sweaty and it appears she may be having something resembling an orgasm. This is happening every night like clockwork, and will happen in different locations in the house. She also will refuse to wear two-piece pajamas, only nighties, and if we do get her into two-piece ones, the activity will continue regardless, with the bottoms down, in the middle of the floor. I'm assuming this is some time of masturbation, but it's a little unsettling at her age, especially since it seems to "finish" the way it does (is it possible for someone that age to have an orgasm? I can't remember from my own childhood). This is very awkward for me to ask, so I appreciate your sensitivity and help.
Thanks.
Taylor, single mom

Most likely it is exactly what you think. Little kids, even babies, do masturbate, and some little girls can orgasm. Just find some way to encourage her not to do it in front of other people, and otherwise, don't worry about it.

I don't want to cause unnessacary concern but i thought i would ask, is there any chance( even the smallest) that she may have been sexually abused? It is common that once becoming abused they may excessively repeat the action on their own as a way of releaving stress or to try to sort what happen in their own mind.
It is very likely this is not the case, don't stress, but if you think there is any chance this is the case talk to your daughter casually. Has there been any other unusual behaviour that started around the same time?

Generally sexual abuse produces a number of changes in children's behavior. What they are can vary, but one new habit isn't much evidence all by itself. Of course, if a kid also changes in other ways, or changes in ways that are alarming, then worry.