Tiny twinkling white lights-does anyone know what these are?

I have had this happen once before.  The first time it happened, we were camping.  I was sitting out away from our group in a lounge chair.  I opened my eyes and all I could see were these extremely delicate and tiny white lights (almost looked like the stars in the night sky, during broad daylight).  They twinkle and were moving.  I opened and closed my eyes a couple of times thinking there was something wrong with my eyes. But, my eyes seemed fine. It last for about 1/2 hour, and then the lights were gone.The second time it happened was just a few days ago.  The big difference was that I was indoors this time.  I can't recall how long it lasted this time, because I was trying to focus on them to see if I could figure out what they were.  But, I just have never seen or heard of anything like this.  I am at a loss.  Anyone else out there ever experience anything like this?  Any ideas what this is or what it's called?