Back in black and white TV days I remember seeing a short film about Jewish students studying the Torah. And they were most of them nodding. When I looked it up today it turns out to be called "Shuckling". ( A tough to find on google there is a comic turtle called Shuckle and oyster shucking, A lot
of noise but it is there. )
When I thought about this gentle nodding it seemed that it might change your brain chemistry by refreshing the fluid in the brain. Shake things up a bit. But it might be a bit exhausting, if you were not reading something exciting.
So a robot to shake the reader gently might be a product that would sell to the fringe.
Or a chair built on top of a small spring loaded teeter toter. my office chair has enough wobble in it to shake for some time with just a slight push.
Or just a set of scientific studies to find out if anything useful is going on when Shuckling, nodding. You could start with two groups reading the same text on a train that vibrates and at the not shaking train station. Taking a test on the material. Or bus vs train for two kinds of vibration.
A lot of commuters already read on the way in, so getting volunteers should not be to hard.
Plenty of time to see if there is a suspicion of something going on before tapping spines and brains for fluids.