If you force a test subject to wear mirrored sunglasses that reverse the polarity of their vision, making it seems as if they are wandering around in an upside-down world, their vision will turn right-side up again in a few days. It seems the brain automatically orientates itself to a ‘proper’ top-down orientation; we’re psychologically asymmetrical.
You can test it for yourself: hold a book in front of you and tilt your head as far to the right as you can. You can probably still read the page without any exertion or mental correction: your brain automatically readjusts. Interestingly, if you hold your head straight and then tilt the book, the brain doesn’t correct its visual orientation, and you can read the book only with difficulty. This seems to imply that your brain only reorientates its vision when the world tilts, not just a single object in isolation.
With that all out of the way, can anyone in holy hell explain the idea behind these Bed Books — sideways-printed editions of all your favorite public domain classics? The product’s slogan is “Now you can really curl up with a good book!” But, if anything, this seems like it would be worse than reading a horizontally printed book, because the Bed Book would effectively be tilted in isolation compared to everything else in your reoriented field of vision. Silly inventors!