sudden darkness - black screening

Well, i'm not sure what is going on. I am creating a game map, putting written books in chest and hiding them for the "player" to find as they play the map.

One of them I put into a ravine. I hid an emerald block behind coal and then placed diamond ores behind in, 15 i think. I was adding a written book into a chest I was going to cover up with the emerald and then suddenly.... black screen.

I can see an item my character was holding, but everything was black. I tried hitting around to see if I glitched into walls, tried flying. nothing happened. I ended up using /kill to respawn and return to the spot. It happened again, I'm just standing in the area and everything is fine... then poof. black screen.

It occurred again after that. I then came to report it. No idea what is happening. =/ sorry I can't give you more info. I had a nightvision potion on the whole time, and tried re-drinking it even though it still said i had it on, but still blackness.