Hi Philski,
I'm afraid I don't have the answer to your question but can affirm they contribute. I spend all day in front of a computer and if I don't take breaks can get a terrible migraine.
My husband bought himself an Xbox for Christmas and I tried playing a game with him while I had a headache (stupid I know) and in about five minutes my headache was a full blown migraine and I was vomitting in the bathroom.
I suspect it's the flickering lights and movement that triggers the migraine, but that's just a guess.
Nicky
Fall seven times, stand up eight.
--Japanese proverb