Actually, I have a little piece of software I downloaded from somewhere...I think it was called "flux". It would change your computer display's color palette to dull in the evening. The research sounds similar. Not so much to "blame" the iPad, as any bright LCD device, when compare to a relatively "dull" eInk device.
I used to have an eBookwise, which was backlit, and I would also turn the contrast down at night...