I received this sound machine the other day in exchange for an honest review.  I used the sound machine a couple of times.  I tried all the sounds but the one I liked the best was the babbling brook.  Th other sounds rain, thunder, white noise were too distracting and I could not fall asleep.  I am one of those people that really have a hard time sleeping with any sort of noise unless I am extremely tired and then I really do not need anything thing to help me sleep.  But if you can fall asleep with the TV on, this sound machine might be for you.  I only timed it for 15 minutes, but I liked the idea that you could time it for three (3) different lengths. [This review was collected as part of a promotion.]