That's exactly what happened to me. Not enough sleep, thinking I can run all nite chasing the international markets, and playing superhero for the US day session.
Quote from mr_minty:
for me, it's any time i get taken out of flow..sometimes it's because i become very conscious of myself, my p&l, my emotions etc...
the worst is when i can't even get into flow, which usually happens when i don't get enough rest, exercise or when personal problems start intruding on my trading.