So I have just awoken from a dream, but it was sort of strange,
It sort of went dark for a brief second and then went normal and then went dark again I mean like someone turning of a light switch… Anyone have any idea what that means?. It’s the first time something like that has happened.
Moved from General Lucidness. 
Dreams are tied to your imagination, so when the lights went off it means you stopped imagining what was around you, for whatever reason, possibly including the thought you had shut your eyes. You should seek out the precise reason within yourself, though, as we cannot tell from here what would have been your motive to.
Thanks for the advice, 