between being at the 'foreground' and 'background' of your daily experience?

For example, a week may be spent just feeling sub-par, tired, kind of slow, kind of down, nothing really excites you, the future seems pretty blah, but you can still laugh at someone's joke, still enjoy little moments or a good meal, still function - maybe you don't even realize you're depressed at the time...and then other times is comes rushing to the fore and completely consumes you, all you can think about is your own despair, can't function at all, don't want to live etc., then in another week or so it recedes again, maybe you even feel pretty darn good (?)

I'm asking because I used to think my depression would go from 0 to crisis overnight, but I'm now wondering if maybe I've just been ignoring mild depression and thereby missing my window of opportunity to be more proactive...