Heh not to brag but this week I've been just full of energy, feeling just amazing. I attribute most of it to my diet though, I have been on a high protein, high carb, low fat diet and eating extremely clean and been feeling just great. For me it could be just the contrast between this diet and my last diet which was low cal ckd style.. I was so used to being out of it and completely lethargic that perhaps actually having the normal/above average energy levels I have now seems like a massive high. Could be you're just real busy and outdoing yourself abit mojo.. or maybe not getting enough quality carbs. Most of my carbs have been coming from whole grains, bananas and veggies these days and I find my energy levels remain more or less consistent throughout the day. I've also been drinking a fair amount of skim milk and I won't go more than three hours without eating something. I'm human though, will usually be a little tired for a couple hours after the wrokout but shower and food always helps. My guess is it's etiher or schedul or your diet.. also how well do you sleep? Even if you are sleeping 8 hours, it may not be quality sleep. PErsonally I often wake up alot during the night and then can make me tired the next day.