Some may say that the drooping of the upper eyelid occurs in many life situations. For instance, when a person cries or the foreign body gets inside the organ of vision. At the same time, it can be the most distinctive sign of Myasthenia Gravis. Another name for this symptom is Ptosis. It can be the first warning sign. The main reasons for Ptosis to take place are sleep disorders or muscles getting too weak and exhausted over time.