Another way to look at this is how many people need more sun and regular sleep and instead are doing unnecessary treatments?
ADHD is highly treatable with medication, and any other intervention is at best mild mitigation. So how many? Amongst people with ADHD, basically nobody.
Sun and proper sleep is certainly helpful for people with ADHD but the likelihood of them getting that is vastly increased if they’re medicated correctly.
Just an FYI, in circles similar to HN, people will respond very negatively to anyone suggesting anything that might hint at tightening amphetamine prescriptions.
That is doubly important given that one of the effects of the medications, is to disrupt sleep.
Any psychiatrist worth a damn already considers these things.
"ADHD" symptoms can manifest for a variety of reasons, and that's why good ADHD testing involves multiple exams alongside the traditional ADHD ones to help figure out what actual issues are present.
Also, comorbidities make this all the more complicated. Your assertion that people need "more sun" and "regular sleep" could very well be true, yet someone can still have ADHD.
Roughly, zero. Stimulants are not a fun dependency, come with a bucket list of side effects and downsides, and only mitigate one aspect of ADHD.