Malaise and fatigue are symptoms that describe an overall feeling of sickness and tiredness. Malaise means feeling generally sick, uncomfortable, or in poor health, while fatigue means extreme tiredness (not just feeling sleepy) that affects the entire body. Malaise and fatigue often occur together due to a number of infections and illnesses, including influenza (the flu), thyroid abnormalities, anemia, cancer and cancer treatment, rheumatoid arthritis, fibromyalgia, and more. Malaise and fatigue may also be caused by mental health conditions, such as depression, or by experiencing grief. Chronic fatigue syndrome (CFS) can also cause malaise and fatigue, and the symptoms typically don't improve with rest.