I have had broadband visual snow since I was a small child always with red in it. I would lie in my bed at night looking at it.
Never knew there was a name for it until maybe 10 years ago with the internet. Thought everyone had it. I am 47 and though it is there I dont notice it much now. Even as a child I had a lot of anxiety & the more anxious I am the worse it is. I do have an autoimmune disease, Psoriasis & Psoriatic Arthritis. As for medications causing it I had obviously not taken any hallucinations at age 4. I do think there is a link to anxiety. I do take medication for depression / anxiety but I do not think it affects the snow one way or another.