I never leave BTC on the table overnight. Cause you never know when the big surprise is going to hit.
Want to be awake and react when that happens.
This is important. I cannot stress this enough. Leaving stops/limits on Bitcoinica open overnight are a surefire way to screw yourself over, because they take into account only the price, and not market depth, direction, or volatility (the things you would normally consider if you were manually trading on Bitcoinica). Also, just watch what happens when a spike triggers your stop or limit at a very bad price. In volatile markets, I've even had both the stop and limit get triggered, and this can lead to extremely unpredictable results.
Bottom line: please trade while conscious