It might sound crazy, but mouth breathing is linked to ADHD and all kinds of issues, likely due to lower nitric oxide levels and less stimulation of the pituitary gland. Expect the field to grow in the next decade. Lots of us are now having problems because of the reduction of breast feeding, amongst other things.
One night a few weeks ago I tried the method of taping my mouth shut before going to sleep. I woke up the next day feeling super sick and lightheaded, presumably due to lack of oxygen. There definitely seems to be an issue with my nose breathing.
> now having problems because of the reduction of breast feeding
Do you have a link to any studies that indicate/confirm this?
https://www.ncbi.nlm.nih.gov/pubmed/20129889
It's not even a question of IF for those who are into this stuff. It's really a question of WHY for the researchers. But for those in the field, the solution is simple and you don't need to know the why, you just work around it (by nasal breathing!)
Here's some more that are more about the sleep apnea side of things:
https://www.ncbi.nlm.nih.gov/pubmed/12615622/
https://www.ncbi.nlm.nih.gov/pubmed/14523179/
https://www.ncbi.nlm.nih.gov/pubmed/15342852/
Point being: before you think you (or your kid) is "ADHD", see to it that they are breathing and sleeping properly. They're just so tired they become irritably unstable and unfocused. Lack of sleep = kids are a mess