If you've ever found your eyes tiring by the end of a movie in your home theatre – and it has nothing to do with the writing, acting, or production – you may want to look into something like a bias light.
I knew about bias lights once but over the years, and through several changes in TV's over the years, I had forgotten just how much a bias light can improve one's enjoyment. Back then, I had (among other TV's) a 57-inch CRT rear projector, but while watching it I noticed that the picture would tend to dazzle my eyes, and not in a good way.