Anyone else get like "pings" in their heads? As I am falling asleep or sometimes when I feel tired, I get these "Pings" on the side of my head. Sometimes when I feel wide awake, too. They sort of feel like when you get a sharp zap type head shock, instead these have like the "Ping" that sort of resonate through the brain that go through my head. As if there was a submarine inside my head sending out a soundwave. Quite a few time strong enough that they snap me awake. Just curious.