>>>while you're sleeping<<< Hmmmnnn, do I detect some laziness in that question?
But seriously, Brim, I personally could NEVER use anything that was buzzing away in my ear while I was trying to sleep, though yes, I have taught myself a for. language (Spanish 1) using a high-school text (while I was wide-awake :wink: ). I made sure to get the cassettes, too, as I was not just interested in reading Spanish, but in speaking it as well.
Do be aware that truly mastering a language (not just reading it) involves LOSSA practice! But it's not drudgery, it's fun (at least I always thought so).
Good luck with it!