I have always wondered...how much does being tired, such as working 8 hrs at your job after only getting 5-6 hours of sleep, affect your actual workout? Will it only affect the fatigue you have during your workout, or will it affect the max that you can handle? Does it affect your running/cardio fatigue as well? I want to know because I work 8 hrs a day during the week, and I tend to take naps after work before I go to the gym just to have that extra energy. It seems as if it helps a lot as far as me being alert...but even when I'm tired as hell and go to work out, I don't notice a difference with the max weights I will use. I will notice that I may get tired quicker...but I don't really know how much it affects me when I'm lifting weights. When I play basketball, it's similar...I tend to be ok when I first start, but I may end up getting tired faster than usual.