I know I have definitely over the years danced on the line of adrenal fatigue, and even had times where I did a long jump over that line. When I used to be a restaurant manager I would be drinking two red line extremes and maybe and adderall lol. Hey don't judge me a 15hr day in a kitchen is not easy haha.Now since I totally gave up all artificial stimulates for years, the coffee we all partake in gets me rev'ed up.I also have used different things to clean off my receptors over the years as well. Benedryll and even ketotifen. I'm not advertising this as something people should do, and as well unless you are taking things beyond caffeine you shouldn't need this. Remember though receptors do build up a tolerance to things in general not just if you are taking something like Clen