Only reason is because really never lasts the entire 2 weeks without let up. I could feel very sad and drained for several days but then there will be a day or two thrown in there where I feel perfectly normal. One of the big factors determining if someone actually has depression is if their symptoms last for two weeks or longer without any let up according to the DSM-5. There's probably more factors that play into that but that's just what I've learned over the years and I don't want to just assume that's what I have since self diagnosing doesn't do you any good.