I experience this every time before my lucid dream starts. I recieve shock in the middle of my forehead (the 3rd eye area), right before the dream begins.

Its a little hard to describe, but it looks like a white light expanding, a little bit like when you turn off your TV, except in reverse. It feels like getting smacked in the head, but without any pain. This whole process lasts for about a second.

I get this every time I become lucid, or wake up too fast from a lucid. Does anyone else experience this?