Natural killer cells slay fatigue.

Up to 20% of adults report fatigue so severe that it impairs work and home life. Recent research that looks at the interaction of the body's immune, endocrine and nervous systems, as well as the role of specialized white blood cells called Natural Killer cells, offers new hope.

Natural Killer (NK) cells, discovered by immunologists in the 1980's, are a type of white blood cell that earn their name because they have a "natural," or innate, ability to identify and kill any "non-self cells" (the microscopic invaders or abnormal cells that mean us harm). NK cells patrol your tissues and blood stream on the look out for "non-self cells." Once identified, they immediately attack, destroying these harmful cells before they have a chance to take root and cause problems.

When NK cells are overwhelmed, they "sound the alarm" that the body is under attack or injured, initiating a cascade of cytokines (immune system messenger compounds), that recruit other white blood cells to the scene. The production of antibodies and inflammatory factors are stimulated, metabolism and body temperature change to make the body a hostile environment for abnormal cells (which is why we feel fatigued and tired), and the brain gets the message to seek rest and recovery. When the injury or infection is cleared, NK cells help rebalance the immune system and we feel better.

NK cell function fluctuates throughout our lives. It generally declines with age and in response to emotional stress (like grief, or pressure at work or home) and physical stress (such as ...