Sunday Night Blues is a fairly well-documented condition (and, I might add, a good band name, for those who are looking for one). It is also, I might add, an entirely curable condition. Or at least, in a roundabout manner. See, the feeling occurs due to the upcoming end of a work or study-free weekend and the onset of going "back to the grind" so to speak. This fear and angst is most common, then, in those who have a traditional work or study week.
The cure to this condition, of course, is to simply reach the point in which the weekend is no less stress, anxiety, or depression free than the week, thus preventing a case in which Sunday night seems to be the penultimate ending of a slightly higher point. By creating a situation in which all days are equally miserable, then there is no need for an onset of an acute condition on a specific day of the week. Instead, the entire week can be one of perpetual angst and sadness.
The fact that this cure doesn't so much exorcise Sunday night blues so much as create a situation in which said feeling is the default state is neither here nor there. Sunday nights, under this new condition, will officially be no more worse than any other night.