For those that asked, here's reasonable explanation of the differences found in oats, oatmeal, etc., though I'm not a proponent of the Zone Diet.
http://www.formerfatguy.com/articles/oatmeal/oats.asp

And, truthfully, the idea of cooking a grain overnight makes me think of library paste. But I like to chew my cereal which can only be done if the fiber is kept intact by not overcooking (and then it doesn't cause as much of a blood sugar spike). Just my humble opinion.

Even Bob's Red Mill only recommends cooking for 8-10 mins.
http://www.bobsredmill.com/recipes_detail.php?rid=1367