I have ADHD as well, and I started treating it with meds quite a few years ago.

Before I took meds, I was generally very productive, but it was a huge strain.

I've always been pretty religious about getting enough sleep, and so back then I was consistently getting more than 8 hours of sleep every night. And I would wake up refreshed, and I'd feel great.

Then after a work day containing a fair share of intense concentration, I would be absolutely exhausted. Most days, I'd take a 90 minute nap as soon as I got home, so I could have some kind of useful evening.

I've always been, for myself, extremely reluctant to take any kinds of medication. I don't put that on anyone else, but it's just my own personal perspective. So I resisted getting the ADHD treated for a long time.

I finally went in and got a scrip for Adderall.

My blood pressure and pulse rate were, at the time, in the normal range, but slightly high. So I did some experiments, tracking my BP and pulse rates at various intervals after taking the meds.

Even though Adderall is speed, for me, it clearly lowered my pulse rate and blood pressure after I took it. My mind wasn't racing around in many directions at once, which I assume allowed my BP and pulse rate to go down further into the normal range.

Further, I no longer needed to take a nap in the afternoon after work.

Note: this wasn't because the meds were keeping me awake. I never take them after noon, so their levels are very, very low when I go to bed. Sleep is still important to me.

I manage my consumption of the ADHD meds pretty rigorously. My doctors have always given me that flexibility by giving me many tablets of small dose, so that I can slice and dice the dose as I see fit. This has been quite useful, since I'll actually dose myself based on what's expected during the day. And on days off, I'll almost never take the meds.

One last point: I don't think ADHD is a mental illness per se. I know that people who have it might not fit as well into some parts of our modern society, but more than anything, I think it's just a personality trait, one that provided evolutionary advantages at some point in our past.