Good stuff above. Personally, I think there are basically two things here. There's dictionary 'sadness,' which is basically a state of unhappiness or sorrow. And then, there's dictionary 'depressed,' which is the state of general unhappiness, despondency, or sadness. Kind of the same thing, really. That's the first thing.

But then there is also clinical depression. which today is most often defined by the DSM 5, one component (of many) of which is sadness. That is the second thing. Sadness, in combination with these other things, several mentioned above, can add up to a state of what we usually call clinical depression, if the right criteria are met.

Anyhoo, that's how I think of this. And I will just say lastly, I am no psychiatrist, but having sadness plus anhedonia plus sleep changes is sort of starting to me to sound like a bit of a clinical depression-type situation. So I would pay close attention to what is happening. You definitely do not want it to get out of hand. I hope you feel better soon!