Re: Why is it recommended not to watch television in the dark?

Well, it is harmful if you to watch TV in the dark. Let's see this from 
the eye's view. 
In the eye, there is a small opening called the pupil, which controls the 
amount of light that enters your  eye. This amount is  calibrated 
according to the lighting of the surroundings. If it is dark, your pupils 
widen to let in more light, and vice versa. This helps you in seeing 
things in a proper shade, colour, etc, and many other factors which 
affect  sight. The important thing to remember here is that the pupil 
takes some time to adjust to light changes. 
Now, when you watch TV in the dark, the amount of light emitted by it is 
variable and constantly changing. Your pupils can't adjust to these light 
changes as fast as they occur, and that puts a strain on your eyes. If 
there is light in the room, this reduces the strain by giving a constant 
background against which the pupil can accomodate. Hence, never watch TV 
in the dark.
In movie theatres, the same explanation is there. But, can you tell me how 
many times do you go to the theatre? not as much as you watch TV. Hence, 
no one notices the difference. But, you must have noticed that as soon as 
you come out in the bright light of the day from the movie theatre, you'll 
be blinded, and it will take soe time before you can see clearly. That 
will give you an idea of how much time it takes the eye to adjust to light 
differences and why TV shouldn't be watched in the dark.