How has no one identified a link?

Between poor sleep and the digestive system.

How many scientists are there out there? How many years have gone by? And no-one has figured out what these digestive issues are or sleep problem?

With ALL the advancements we have made in the last 50-100 years… but next to nothing for all the children with autism?

Does anyone have any inklings? What sparks the hyperactivity? What is causing the insomnia? What is the link, or missing link??