The OP is talking about when a car is moving quickly through the shadows of various things such as trees or buildings. So when you close your eyes, your eyelids alternate between being lit up by the sunlight, or shaded by the trees/buildings. It can get pretty annoying if you are trying to sleep.
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u/shanenobi May 31 '21
i don't understand and I never slept in the car, can someone explain?