The first stage of adrenal fatigue is usually hyper, or too much cortisol output because of chronic stress somewhere in the body. After the adrenals get tired with no more reserves, they supply too little. They shrink.
A definate chronic stressor can be an on-going candida yeast infection, or basically a depletion of the healthy flora. See http://www.thecandidayeastanswer.com.
You have to find where all the poisons are coming from...the endocrine disruptors.
Lack of rest is a stressor...major.