Relationship Between Heart Rate Variability and Sleep Among Girls and Boys With Abdominal Pain-Related Disorders of Gut-Brain Interaction. - Kamp KJ; Burr RL; Matherne CE; Simonds E; Murphy T; Heitkemper MM; Levy RL; Shulman RJ; van Tilburg MAL (Neurogastroenterology and motility, 2026)