I have dealt with fatigue for the past 8 years. I have tried a variety of diets and supplements (including those mentioned in James Wilson's book),with little success, and last September, began seeing a naturopath. He diagnosed me with adrenal fatigue, and I spent a small fortune on visits and supplements over the next 9 months. Better, but not 100%. Then in February, went to the doctor for my annual check up, and mentioned the fatigue. She decided to check my vitamin D and calcium levels. My calcium was 10.4, slightly elevated and my D was very low. I was vaguely familiar with the relationship between elevated calcium and the parathyroid from a friend's experience with this in the past. Long story short, after having my calcium levels drawn 3 times over a 4 month period, all in the 10 range (10.4, 10.9, and 10.1), and being told by 2 doctors this was fine, I researched the internet and consulted an expert on parathyroid disease out of state, who diagnosed me with a parathyroid tumor. I went to him for surgery, had the tumor removed (minimally invasive, radioguided parathyroid surgery), and within 10 days, the fatigue and brain fog were gone. I would highly recommend anyone suffering from fatigue to visit parathyroid.com and get your calcium levels checked. If they are in the 10s, you have a problem, and don't let your doctor tell you otherwise. The human body was meant to live in the 9s, and does not feel good in the 10s, when it comes to calcium. I realize not all fatigue is caused by this, but hyperparathyroidism is an underdiagnosed disease with an EASY CURE!! Rule it out with a calcium check.