I used to run a little tablet 24/7 in my bedroom, with the image tinted red to be easier on the eyes at night, but it was still too bright at the other end of the room, even on the lowest brightness setting. To make things worse it was an unreliable tablet.
I'm now running a Raspberry Pi 2 using OmxPlayer to stream a few cameras to this monitor, which I got because it has some of the best available black levels:
Amazon.com: BenQ EW2750ZL Revolution Eyes 27" Video Enjoyment Monitor with MHL EW2750ZL 27" Screen LED-Lit Monitor: Computers & Accessories
This alone isn't good if you like to sleep in the dark, though. Even at the lowest brightness level, the backlight is clearly visible and video streams are annoyingly bright. I was able to solve this by taping on about a half dozen layers of red cellophane.
Amazon.com: 30 in. x 50 ft Red Cellophane Gift Wrap high quality roll By Crown: Health & Personal Care
The result is that video is clearly visible in a dark room, but does not throw out so much light as to bother me. Those who are especially sensitive to light could add additional layers of red cellophane, or even add a layer or two of gray or black cellophane.