"Close the glass, you'll confine a draft"?

I always hear mothers on TV say something similar to this but wasn't sure if I inherent the phrase. I can't find it online.
I've had a couple situations where on earth I left my bedroom windowpane open and get sick. My throat would be dry and seem as if the cold nouns affected my nasal passage. Is that what it is? Usually it is the allergens that are in the "draft" that create the symptoms. If it is a cold draft your body has to work harder to keep hold of its temperature regulated which can lower your resistance to microorganisms and that too can manufacture you sick.
Mom knows best! I other keep my window closed. :)