Rubbing Your Eyes
While you probably don't even realize you're doing it, rubbing your closed lids can cause a spike in the fluid pressure inside your eyes, up to ten times the normal amount. Over the years—especially for those with dry, itchy eyes—frequent, mindless rubbing may contribute to the development of problems associated with intraocular pressure, including shortsightedness and glaucoma (which can lead to blindness).
Try wearing mascara and a darker shadow: The risk of looking like Alice Cooper will discourage you from touching your lids when you're feeling sleepy. If you suffer from dry, irritated eyes, seek treatment for the itchiness.