The photoreading system takes advantage of the fact that your subconscious mind sees all and remembers all by having you scan pages literally focused at the center and not on any single word, flipping a page every 2 seconds. Then you use "rapid reading" to sort of pull information out of the book, like zoning in on what you intended to learn from the book. It is most effective if you are reading with a purpose, such as to glean specific information. I've only begun to study the photoreading stuff but if it works It would not seem far off to be able to do the same quick scanning of a book then use lucid dreaming to pull the information from your subconscious. Not exactly learning with audio stuff at night but similar.
I just had an insight...I've also just begun reading "Think And Grow Rich" by Napoleon Hill. One of the key concepts in the book is Faith. Not faith such as you have in a religious context but ingraining faith into your subconsious through positive affirmations. Positive because any emotion you assosiate with those affirmations will increase its power in that direction. He said when discussing this topic that the repitition of that information will bring you to 100% belief in yourself and those affirmations. I know those sleep aides like quit smoking in your sleep or lose weight etc work by essentially reading these positive affirmations to your subconsious. The only problem is that while your subconscience can send information to your conscience at times, otherwise known as a hunch, intuition or gut feeling you cannot however pull the information consciously
Hope this helps.