While there's some dispute about whether "adrenal fatigue" is a recognized medical condition, there are some commonly recommended supplements. You might try some DHEA, pregnenolone and maybe GABA supplements. They're still legally available in most states. DHEA and pregnenolone are hormone precursors, naturally produced by the body but sometimes under-produced as we age or are ill. In that respect they're similar to melatonin, a naturally produced chemical that helps us sleep but tends to be produced by the body less as we age, or are under stress. So the supplements can help.
Due to a wonky thyroid and auto-immune disorder I've just started taking DHEA, pregnenolone and GABA, just to see if it helps with my energy level. The doctor took me off thyroid supplements for a month to check my reactions and will do some tests and a biopsy later this month to see what's going on. When I was taking thyroid supplement my blood tests were normal, but I still had the symptoms of a thyroid disorder. I'm curious to see how the tests turn out.
I've been taking the supplements for only a day, too soon to say anything about whether they're helping.
Incidentally, DHEA and pregnenolone are the main ingredients in many "male supplements" that are implied to help with erectile dysfunction -- although manufacturers aren't permitted to make any such claims. But those voodoo potion male enhancement pills include stuff we don't really need, like yohimbe, an alkaloid that can have stimulant and mood enhancement effect on some folks -- but many users complain it makes them feel jittery and sick.
So it's cheaper to just buy generic DHEA and pregnenolone and add only the other stuff that you like. I drink enough coffee so I don't care to add yohimbe or other stuff that the male enhancement makers use to justify charging ten times the price.