What is true is that fatigue is far from being a key symptom. This can be seen in a number of diseases, such as different infections. However, it can also be a symptom of an autoimmune illness. People with broken immune systems often suffer from fatigue that does not improve even after a good night's sleep.
One such example would be that Hashimoto's sufferers can suffer from chronic sleep disturbances, which leads to consistent fatigue. For such cases, daytime sleepiness is a speculum writer, as well as nocturnal insomnia. This makes you sluggish both physically and mentally.
Another common autoimmune disease to consider as an adjunct to fatigue is Sjögren's syndrome. Other than the other disease-typical symptoms, patients also often have to deal with permanent fatigue as another life hamper. So when you find yourself overly sleepy and without strength for no apparent reason, think about autoimmunity.
