Despite the effects of the paralysing drug, the brain also still functions. So if you wake at the wrong time, you may be able to hear surgeous and nurses talking, and understand what is going on. You will be unable to call out,open your eyes, or move, because your muscles will be paralysed. However, you will feel no pain because of the third part of the anaesthetic -a pinkiller, such as morphine.
The drugs of a general anaesthetic are powerful and can cause hallucinations, which may explain the near death experiences described by people who are given general anaesthetic. Many of them say the same thing-they rose out of their body and went down a corridor towards a bright light, and sonetimes they have reported hearing a voice telling them to rectum.