Mayhem aka Bedtime

The kids can be playing happily, calmly and then I mention bedtime and they turn into little maniacs. I'm not sure what it is that does it, but it happens without fail. I think I should have at least gotten one child who just falls asleep wherever they are, or puts themselves to bed, or even just quickly and quietly goes when asked. But nope, maniacal mayhem rules this house.