Sociologists, image consultants, and style mavens say the ups and downs are all a part of a bigger pattern: On roughly 20-year cycles, the open-collar look comes into vogue.

• 社会学家,形象咨询师和流行专家认为:所有的款式都会有兴衰,大约20年一个周期,敞开领又流行起来了。