One in five parents admitted their stress likely negatively impacts their children's enjoyment of the holidays, according to a C.S. Mott Children's Hospital National Poll on Children's Health at University of Michigan Health. Parents can set unrealistic expectations of how the holiday season should be, said poll author Sarah Clark, a research scientist in the department of pediatrics at the University of Michigan in Ann Arbor. She is also co-director of the C.S. Mott poll. -CNN Health