From the NYT:
Happy people spend a lot of time socializing, going to church and reading newspapers — but they don’t spend a lot of time watching television, a new study finds.
That’s what unhappy people do. […]
But the researchers could not tell whether unhappy people watch more television or whether being glued to the set is what makes people unhappy. “I don’t know that turning off the TV will make you more happy,” Dr. Robinson said.
My personal thought is that this is much more correllation than causation. I do not think TV itself is the cause of the unhappiness, likely just another symptom. In other words, I think some people who watch a lot of TV can be very happy.