According to a pervasive belief in the German-speaking world, it’s essential to avoid drafts. They cause all kinds of diseases, including muscle stiffness and colds. This is why houses and especially sleeping areas must be kept draft free. I have not encountered this belief elsewhere and there is next to no evidence supporting the negative impact of drafts of health. Tellingly, there’s an article about drafts and their possible impact on health on German Wikipedia, but not on English Wikipedia.