Well, generally speaking, stress can not lead to flashing light in the eyes. First, you should know that if you have flashes of light, it can be an indicator of a serious eye problem that needs immediate treatment. And also, according to many experts, flashes accompanied by vision loss or by a large number of floaters, small specks, which appear in your line of vision and appear to float or dart from side to side. Of course, there are many reasons which can cause flashing eyes, for example, severe recurrent headaches caused by blood vessel spasms in the brain that last from a few hours to several days, often can cause flashing light symptoms. Besides, Retinal detachment or retinal tears can also be a cause. Anyway, if you have this symptom for a long time, I will suggest you go and see a doctor.