If you are looking for a cause of your fatigue and you don't know how your adrenal glands effect your overall health, then I would highly recommend the book "Adrenal Fatigue" by Dr. James L. Wilson N.D. D.C. PhD. At least 80% of the population has or will suffer from adrenal fatigue or hypoadrenia. MDs are not trained to identify it. They only identify the extreme form of it called Addison's disease. The book gives you three tests you can conduct on your own if find out if you suffer from it and a lot of options so you can do something about it.
I give it a strong thumbs up and this message an R too.