Child sim won't go to sleep

I had the problem with my toddler and it was the radio. it wasn't very close to him but apparently it was enough to bother. I caught the thought bubble he had which was musical notes with a red circle slash over it so that clued me in. There isn't any indication anywhere except for this random thought bubble after trying to get him to sleep about 5 different times in a row. The radio was not in his room. The radio was on a different floor! But until I turned it off, he kept getting up. Once I turned it off, he finally slept like normal. My twins never had that problem and they are very close in age to my toddler. It seems not all toddlers have this problem. I guess it's a personality thing. Hope someone can use this info!