Studying while asleep?

Got a test tomorrow?   

Well then, listen up! 

Scientists from Northwestern University in Chicago have found that "hearing specific sounds during sleep can improve memory and recall."  It has something to do with the way our brains work- even though we're asleep, our brains are still very active.  These scientists believe that we "consolidate memories as we sleep" and that during this time period "we can influence which ones we will later remember more strongly."   

Scientists asked a group of students to look at 50 objects, including a cat and a kettle, which were all paired to a specific location on a computer screen.  They then asked the volunteers to lie down, and as they slept, played them a series of sounds related to half of the objects, including a cat's meow and a tea kettle boiling.  Tested later, the students were better able to correctly place an object's location for those items whose sounds they had heard while sleeping. 

So the question remains, is this an effective study tool?  Obviously you have to learn the material first, but this may be a way to keep the stuff you just learned "up front" in your brain's file cabinet.   What do you think?