The way we see a TV is image is influenced by a number of factors, from the capabilities of the display itself to neurosensory and human factors. Beyond the display, the environment in which we view an image has a tremendous impact on the way the image is perceived. 

In order to get a high contrast picture we need to eliminate any ambient light hitting the surface of the screen. But complete darkness isn't a good answer as it can cause eye strain.  

As Joe Kane wrote as the chairman SMPTE's Professional/Studio Monitor Working Group, the colour of the light behind the set should be the colour of daylight in a hazy sky or 6500K.   That's the same as the colour of grey on a properly optimised set.  The ambient light should be no higher than 10% of the peak light coming from the set itself, which is why a dimmer is also important.

MediaLight bias lights are extremely close to 6500K with a CRI of 90+. Rather than buy commodity LED strips that are often passed off as bias lights, we source diodes of the highest quality and have the strips made just for us.  In other words, the days of blue or green-tinted LED-based bias lights are thankfully behind us.