Stress exposure, sleep, and metabolic health all have both distinct and overlapping effects on immune health. Sleep has a profound effect on the immune system, and consistently getting enough of it can improve the ability to fight off infections (or avoid them altogether) and increase the efficacy of vaccines.[1] Excessive stress (either psychological or physiological) can have positive or negative effects on immune health, depending on the type of exposure. For example, temporary stress from exercise or public speaking can have positive effects on immune health,[2] while chronic stress exposure can impair immune health by limiting the ability of the immune system to fight off infections and/or increasing the risk of autoimmune disease.[3] Metabolic health — in particular the ability of the body to regulate blood sugar levels — also plays a significant role in immune health, since impaired blood sugar control and insulin resistance have widespread negative effects on the immune system.[4]