Usually used when a physical blow to the head causes one to visualize flashes or spots.

Physical Cause

It's a figurative way to describe seeing lights from a hit, not actual stars in the sky.

Not Literal

Emphasizes a brief, momentary sensation rather than a lasting condition.

This is about a sudden emotional impact rather than a physical one.

Metaphorically expresses feeling overwhelmed or stunned by an unexpected event.

Can be used for both positive surprises, like winning a prize, or negative shocks, like a loss.