The anaesthetic wouold normally be completely out of your system within 46 hours at the outside. If you are still feeling sleepy, it may be becuse your body is diverting energy reserves to recovering from the surgery. If the problem persists, have a chat with your GP to make sure everything is alright. I've just researched, because I was uaware of what your condition actually is, and armed with the information, I can see that your surgery has been pretty serious, and explains why you are still feeling weak after it. It is not the anaesthetic that's affecting you, but the serious surgical invasion you have undergone, which will take time to recover from. You should be resting as long and often as possible until you feel better.