Over the years I have seen children with autism who have various sensitivities. These sensibilities can be with sound or even light. These issues can be quite problematic for some children, I have had some who need to wear earphones to muffle sounds so that they can leave their house. And for some sensitive children, even household sounds like a loud TV set, a vacuum or other sounds can be challenging for them.
There are certain things that I look for when a child has these types of sensitivities. One is yeast, I have seen heightened sensitivity when yeast overgrowth is an issue so an organic acid test can check for arabinose or other biomarkers for yeast. A mineral deficiency is also another possibility, especially magnesium. A magnesium deficiency can increase irritation and agitation within the body. Supplementing with magnesium has certainly helped some children with light and sound sensitivity. The optimal form of magnesium supplementation would be through IV so that the digestive tract is bypassed. That is not always an option for all families so you can do so in other ways.
You can also supplement with magnesium orally. There are different forms of magnesium to be aware of. Magnesium glycinate is absorbed very quickly. So for many children, doses between 250 – 400 mg can be useful and usually over time you do see benefits. Magnesium citrate is also another option although this form does have a laxative effect which limits how much you can give. So if you are trying to alleviate some of the sensitivity issues, then magnesium glycinate is probably the preferred form. Some other options are an Epsom salt bath which provides magnesium sulfate, you can add one to two cups in a bath at night. Epsom salt cream is an alternative to that and you can use one to one and a half teaspoons applied to the skin two times a day may also help.
So when we are addressing light and / or sound sensitivities in children with autism, the two most common things I look for are yeast overgrowth and magnesium deficiency. There is also a therapy called Auditory Integration Therapy or AIT which can also be helpful for sound sensitivities and auditory processing so you can look into that as well. And light sensitivity often times is assisted by magnesium supplementation since magnesium does play a role in issues like stress and irritability for children with autism.