Oh yeah it is definitely a fact! DD's used to be between around 5-6.30 just as trying to get dinner ready and DH walking in the door. This went on till around 10 months old. My mum said the same thing used to happen with me and my sister at the same time and dad would always walk in and say "Has this baby been crying all day" which made mum feel even worse. I think it is just an inbetween hour - bed, bath dinner etc. Even now at 2.5 we still get an arsenic hour but it is around 11-12 in the day, once again just before food and nap!!