Last night I suddenly remembered about a recording of the human heart beat or white noise can help with babies sleep and also stop crying (if they are not hungry, hot or need changing). I tried it on my 5week old twin girls and it was the quietest night we've had in a couple of weeks. Unfortunately it didn't put my most stubborn twin to sleep before two hours this morning, but it certainly helped to keep them calm. Has anyone else tried it...? I'm considering buying a proper machine now rather than just sound clips from YouTube...