I feel tire d all the time. I did undergoa a lot medical tests like thyroid, liver function, ECG, treadmill, scanning and evreyting turned negatvie except Cholesterol. I am able to sleep well but feel very tired in the morning and have a foggy brain. Unable to concentrate.I amnot using alcahol, but one in a while. I try to avoid such occasion since very few drinks would make the next day horrible. I quit smoking two years back. Please help.