Seeing stars happens when your retina or optic nerve is stimulated without actual light hitting your eyes. Common causes include physical pressure on the eye (rubbing eyes, sneezing), sudden changes in blood pressure (like standing up quickly), head trauma, migraines, or disturbances in the brain. The retina sends messages to the brain that the brain interprets as light, even if no external light is present. Seeing stars can also occur due to eye conditions like retinal detachment, diabetic retinopathy, or ocular migraines. Usually, brief episodes from rubbing your eyes or sneezing are harmless, but frequent or severe occurrences should be evaluated by a doctor to rule out serious conditions.