We have bedroom vents covered with a charcoal colored vent cover. We got them at Camping World. They block most light but a little does get through. But nothing like those light translucent covers we have over other vents.
There are several color options shown here
http://www.campingworld.com/shopping...nt-covers/1529
and this is the one we have
http://www.campingworld.com/shopping...nt-cover/34449
I see they also have it in black.