Put the summary of the bug you're having here

What I expected to happen was...: Nothing just my awesome base i was going to build
Describe what you thought should happen here: I decided to swim back up to see if that would fix the bug

What actually happened was...: I was going in deep water in creative on my single-player world to build a underwater base with a night vision potion so I could see. About 30 seconds later everything was dark. I decided to swim back up and it was gone. I went back down and it happened again
Describe what happened here: I went underwater and everything got dark

Steps to Reproduce:
1. go in a natural ocean thats like 10 or more blocks deep. then go to the bottom.
2. ...throw a night potion on yourself and then wait 60 seconds.
3. ...