It's actually been shown that excessive TV watching _increases_ ADHD tendencies in kids, _decreases_ their learning capability, and for infants, slows their linguistic and motor skills by up to a year.
It has also been shown that in adults, TV has such a "relaxing" (read "dumbing down") effect that your brain activity is _lower_ that when you are at a normal complete rest. You are actually vegetableizing yourself by watching TV.
My recommendation is to give up TV completely. Personally I did not long ago, and I've never been more pleased with myself, I sleep better, I have more time to do what I like to do (recently took up learning Japanese as a fourth language)....
TV isn't your friend, no matter how you turn the table