That means spring fatigue.

The shocker: Researchers say it doesn’t exist. It turns out Germans are no more fatigued in spring than they are in winter, summer and fall. Although that is pretty pooped.
Study busts myth: German ‘spring fatigue’ doesn’t exist – Do we really feel more tired in spring? Researchers in Switzerland say, “there’s no such thing as spring fatigue.” But it is a deep cultural phenomenon in German-speaking countries.
It’s one of the first warm days of the year. The first harbingers of spring are cautiously poking their heads out of the ground, the cappuccino in the street cafe tastes of new beginnings. Winter seems to be over.
Everything seems easier — if only it weren’t for that one feeling that seems to plague many people (at least in the German-speaking countries) every year: spring fatigue.
PS: But Stink-Fuß does exist. Although it is more prevalent in the summer. “Out through the night an’ the whispering breezes to the place where they keep the imaginary diseases…”