Rheumatoid arthritis (RA) is an autoimmune disease where the body thinks the joints are foreign and attacks them. Part of the disease includes fatigue. Now, I've been experiencing this fatigue since the end of March, and some days I know I was on my feet too long or danced when I should've sat still, so not being able to move the next day makes sense. I just blame it on my forgetfulness—I still haven't had RA long enough to remember that my body needs more rest now. But I actually just came across a very informative Web site by the RA Warrior that not only shares pertinent info about RA but also explains where the fatigue comes from.
Naturally when your body is sick (or thinks it's sick, as it does with autoimmune diseases) it releases chemicals called cytokines. Some scientists blame these cytokines for the fatigue symptoms associations with the common cold or the flu. So since with RA your immune system is working overtime to fight a nonexistent foreign entity (your joints), your body is being overloaded with these fatigue-causing chemicals. It all makes sense now! No wonder some mornings I feel like I've been hit by a truck when all I did the day before was take a shower and sit at a desk. If you're interested in learning more about fatigue in RA click here.