HELP with 4yr old -Diet, sleep, hearing etc

My DC is B'H very bright but often asks us to repeat things and doesnt hear us. The school also mentioned this, and we went and got hearing tested.

The results came back totally fine. Now me and the teachers are confused as when DC actually hears what is said, DC is quick to comply and has no problem, 'getting' anything. So I dont think its a processing thing.

Even in the hearing test DC phased in and out concentration wise, until the task was made more interesting, after which DC responded consistantly and appropriately.

I am starting to think down different avenues, like maybe DC isnt getting enough sleep, is having the wrong diet or could benefit from fish oil or some type of suppliment.

Im not super worried but I see DC just cant ''hear'' and want to help.

DC sleeps from about 7.30pm till about 5.45/6am. Eats a lot of carbs (obviously I try and give a varied diet but Im not into making food a battle either), generally is not very interested in food. Is very skinny.

Also are there any therepies or methodologies that focus on listening skills.

I dont think DC has ADD. DC definately does not have the Hyperactivity element but even without that, if something interesting DC can sit and concentrate for a very reasonable amount of time for a 4year old.

Any ideas or suggestions?