Sunlight shimmering off water- yes... I have had that...Sounds like photosensitive epilepsy to me. If you have photosensitive epilepsy, certain types of flickering or flashing light may incite a seizure. The trigger could be exposure to television screens due to the flicker or rolling images, computer monitors, certain video games or TV broadcasts containing rapid flashes, even alternating patterns of different colors, in addition to intense strobe lights.
And surprisingly, seizures may be triggered by natural light, such as sunlight, especially when shimmering off water, even sun flickering through trees or through the slats of Venetian blinds.
I"m not photosensitive but I'm the same way. I remember when going to rock concerts as a kid, if they used the strobe light I would get sort of hypnotized & always wished they'd have used it longer.I am photosenstive...but I do have to say, sometimes I seem to be drawn to looking at flashing lights, even though I know better.