You're absolutely on the mark when you say caffeine can elevate cortisol levels. Caffeine is one of the biggest contributors to adrenal fatigue. I personally love coffee and caffeine... ever since I was introduced to it in my sipping cup (no joke). I was an early addict of caffeine and coffee.
But in my early adult life I went on to redbulls... no less than 2ce a day on top of my coffee habit. The result? Today, I'm 28 and I have damaged adrenal glands. Little did I know, every time I took a sip of caffeine I was stressing my adrenals and increasing the stress hormone cortisol. Don't get me wrong, I adore the smell and taste of coffee but it should come with a warning label ;)