Rolf Dobelli, author of the forthcoming book, The Art of Thinking Clearly, has an essay in the Guardian that explains the many reasons why you shouldn't read, listen to, or watch news. I don't agree with everything he says, but I found it thought-provoking.
News is toxic to your body. It constantly triggers the limbic system. Panicky stories spur the release of cascades of glucocorticoid (cortisol). This deregulates your immune system and inhibits the release of growth hormones. In other words, your body finds itself in a state of chronic stress. High glucocorticoid levels cause impaired digestion, lack of growth (cell, hair, bone), nervousness and susceptibility to infections. The other potential side-effects include fear, aggression, tunnel-vision and desensitization.
News makes us passive. News stories are overwhelmingly about things you cannot influence. The daily repetition of news about things we can't act upon makes us passive. It grinds us down until we adopt a worldview that is pessimistic, desensitised, sarcastic and fatalistic. The scientific term is "learned helplessness". It's a bit of a stretch, but I would not be surprised if news consumption, at least partially contributes to the widespread disease of depression.