The multiple but classical reasons causing the eye stings in the morning must be eye dryness, what is worse than that, eye inflammation (keratoconjunctivitis sicca). The burning and scratchy sensations in the eyes may result from incorrect quantity or poor quality of tears producing by tear glands. Lacking of moisture in the eye attributes to your eyes sting. I mean, you might always suffer a slight eye dry, as the long time accumulated, it outbreaked. Further, the dry eye weakens your vision and may cause eye infections. You need your tears to keep the eyes moist and clean, otherwise the bacteria or foreign objects like dust or other things will make you in trouble inevitably. It is wise to maintain healthy eyes.
Try to use a cotton ball with some warm water to scrub your eyes, so does a wash cloth. But you need head to your optician when it gets worse, or it occurred after sinus congestion or some allergies.