I sometimes notice white flashes of light across my vision especially on a bright wall.its not every day i have anxiety sleep for 7 hrs.i do some workout/running in the morning(began last sat)flashes on the night before my piano exam(i was nervous?

Eye exam : If you have symptoms when stressed it could be a migraine equivalent (even if you do not have headache with it ), but if you have had these symptoms multiple times I recommend a thorough eye exam to be sure nothing else vision- related going on. It sounds like you are a healthy, well-rounded young person but a normal full eye Dr exam would be reassuring