It's related to dehydration. Similar effects r caused by caffeine intake in some individuals when not adequately hydrated. In layman terms, creatine draws the water from vital parts of the body, into the muscle itself, and caffeine just flushes water out of the body. Either way, when your body is not adequately hydrated, it causes a dehydrating effect thus causing lethargy. So drink more water and spread it out evenly throughout the day. BION