My kids will rarely take a nap anymore, they will just lay in bed for an hour staring at the ceiling instead. Usually I just put them to bed early, but on the days they are very tired and cranky I will drive around and if I roll down the windows and put on rap music they will fall asleep quickly! If must be something about the bump bump. I use to try classical or children's lulluby's but it doesn't work as well. I don't understand it either, but I just do what works. Also, the kids dressed themselves today before the drive, which would expain why they are wearing long sleeves and a jacket when it is 90 degrees out!