It is unbelievable to say that I can see stars in the daytime. But it really happens. When I stand up after lying on the ground for a moment, I can see stars and feel a little dizzy. Can you tell me why does this happen?
Don't worry about that. When I stand up suddenly I will feel light-headed too. I think it is a common phenomenon. You can stand up more slowly next time. This feeling often goes away after a few seconds. But if you experience dizziness for more than a minute or two or even feel like you're going to pass out, the situation may be worse than I thought before. So see the doctor and talk to them.
I can tell you why does this happen. When you stand up too quickly, you will have a postural drop. The blood (in your legs) needs to enter into your heart then be pumped into your body. The perfusion pressure drops when you stand up, because your heart is not compensated at this moment, and this will cause a reduction in perfusion to your retina for a moment. At the same time your brain also needs oxygen.