Strange reactions to caffeine

Hi there lovely folks of 7 cups. I wanted to throw a couple of things out there and see if anybody else can relate. I live with ADHD (and yes I'm still a good listener ;) ) and I've found that drinking coffee makes me quite sleepy but also seems to quiet my mind down. It seems that very small amounts of it help me to focus and calm my anxiety but larger amounts make me very drowsy and produce effects that are similar to alcohol. This applies not only with coffee but with soft drinks and energy drinks that contain caffeine. Has anybody else noticed any similar observations or had any other strange reactions/symptoms?

Fun fact: I figured this out when I was a teenager and I had a part time job working as a barista. I knew it was totally understandable to be drowsy for a later shift but I was completely baffled as to why I was totally zonked out mid-morning after having drank 4 cups of coffee. Eventually I put 2 and 2 together and the rest is history.

Oh and ps. if any of you need a listener to talk to who can relate to and understand your struggles and triumphs with the ADD bug, my inbox is always open :)