I know the NEA-BPD is active in New York, you might be able to find the best advice from them. Resources are a "good news, bad news" in the general area right now, I don't think there are tremendous wait-times buuuuut most services are offered virtually rather than in person.
I wonder if he's seen any professionals lately? He might prefer to think of it as a "medical" condition or just a "social" problem he's going through lately. So doctor, therapist, counselor, whatever's most comfortable for him. Is it possible that he has a combination of depression (most common reason for sleep troubles) alongside his ADHD? (I've never personally seen the two together - it can happen, I just wouldn't be able to advise how it looks). But if he is lethargic (drug use, trouble waking up) then often that leads rather ironically to insomnia/falling asleep troubles.
Was he raised as an only child? Is he able to hold a job for more than eight weeks, and if so is there a particular harm you see in him pursuing that while you wait for him to get his head in a better place to re-adopt studies?
Hope things work out!
