Hello Sunny,
Body memories are memories generated by the mind that will allow you to feel as if you are being physically touched. It happens because the mind will recall an event but unlike a dream the body itself may feel pressure and temperature. The mind goes to these thoughts when it is not busy, so entering, during or exiting sleep is very common time. I think the way to reduce it is to release the control those thought have on us. There are all kinds of feelings that these memories produce. Fear, anxiety or sexual may be some of them. Everyone is different. Keep writing and taking up space. We are here for you. Take care.