When there is no thought behind what feels like an emotion, is it really an emotion?

I was talking to my sister and she mentioned that ever since she went off birth control, she doesn’t feel sad for no reason anymore. That got me thinking about times when how we feel could potentially be due to some sort of physical imbalance, as opposed to a thought.

In instances when how we feel is not caused by a thought but rather by the body, can we really call it an emotion? Is it just a sensation that we’re interpreting as sadness because it feels like sadness? Or if it feels like sadness, then it IS sadness even though we can’t find the thought – it (or some underlying belief) is in there somewhere causing it, we just haven’t uncovered it yet. How can we tell the difference?

Or maybe we just initially feel some uncomfortable sensation caused by the body and then we turn it into sadness by how we react to that sensation. Our thoughts transform it into an emotion. We think things like: “I shouldn’t feel like this.” “I don’t want to feel this.” We reject it and try to get rid of it as quickly as possible. We don’t allow it to just be without making its presence mean something negative.

What are your thoughts on this?