I've noticed that if I take codeine or one of the synthetic forms of codeine, not only do I get pain relief, but fatigue lifts. So much so that I can't sleep! I am also able to think more clearly. Most people get groggy and sleepy if they take codeine, but I have read somewhere (I think here?) that codeine helps concentration in people with CFIDS/ME. Certainly relieving chronic pain would remove that distraction and impediment, but I can't think why codeine would (at least in me) relieve fatigue. Anyone else?