[inimino]

Sleeping consists of doing nothing. But you are still breathing, so it's not nothing. I would say watching TV often qualifies as wasting time.

[gosheroo]

Sleeping isn't a waste of time, either.

TV is source of background cultural knowledge and is enjoyable for that reason. When it ceases to be enjoyable one can stop watching.

OK, one might be addicted to watching TV, but that's a separate issue. Here one is using the TV to avoid addressing other problems. True, it might take a period of mindless watching in order to appreciate this. Has that time been wasted? Well, no, because it had to be spent in order to gain that very appreciation.