The adrenal glands don’t really get ‘tired’ in the way that you might expect. What happens is that, after a period of chronic stress, your body starts to run out of the hormone precursor material that it uses to make certain hormones. As this continues, it becomes more and more difficult for your body to produce the required levels of stress hormones, sex hormones, and other hormones and neurotransmitters. That’s when the ‘fatigue’ starts to kick in, and that’s when you need to offer your body some extra support.
Glucocorticoids are potent anti-inflammatories, regardless of the inflammation's cause; their primary anti-inflammatory mechanism is lipocortin-1 (annexin-1) synthesis. Lipocortin-1 both suppresses phospholipase A2 , thereby blocking eicosanoid production, and inhibits various leukocyte inflammatory events ( epithelial adhesion , emigration , chemotaxis , phagocytosis , respiratory burst , etc.). In other words, glucocorticoids not only suppress immune response, but also inhibit the two main products of inflammation, prostaglandins and leukotrienes . They inhibit prostaglandin synthesis at the level of phospholipase A2 as well as at the level of cyclooxygenase /PGE isomerase (COX-1 and COX-2),  the latter effect being much like that of NSAIDs , potentiating the anti-inflammatory effect.