Wow, gdawson, I didn't know this. I did a very quick net search and found several places that 7 hours is the limited time needed. Here's some more info:

"Soak ‘em. As little as 7 hours of soaking any gluten containing grains like oats, barley, wheat or rye in acidulated (acid containing) water improves their nutritional content and destroys phytic acid. Cover one cup of whole or cracked grain with an equal volume of water, and add about two tablespoons of acid to the water. Any live culture yogurt, buttermilk, kefir, or whey is preferable, or use a tbs. of lemon juice (vinegar in pinch) per cup. Let them sit in a room temperature spot overnight-at least 7 hours before you plan to eat them. Cover with a clean towel to avoid any unwanted visitors. (Whole rice and whole millet contain no gluten so soaking isn’t as important for them, if they are gently steamed or simmered for about 2 hours it reduces their phytic acid content.) It’s that easy to improve their nutrition. So, one you wake up in the morning, and look at the bowl of puffy, swollen grains, now so much more nutritious then they once were-look up on the shelf at that box of cereal, and back down-these sure ain’t Wheaties! You want me to eat THAT for breakfast??? I eyed them like that myself, when I first tried them-quite unconvinced that I’d ever be able to choke them down. Boy, was I surprised…"

Thanks again, Ann