A recent article Awake or Knocked Out? The Line Gets Blurrier by James Gorman, published on April 12, 2012 in the New York Times, talks about experiments involving different states of consciousness.
According to what I infer from this article, if you 'wake' a sleepwalker you're then interacting with someone whose 'higher' brain function (i.e. the neocortex: I assume you know what that is) isn't active and in control.
- do not expect an intelligent reaction
- some unintelligent reactions are dangerous
- apart from that it's harmless (though bewildering, perhaps annoying)
See also en.wikipedia.org/wiki/Castle_doctrine#Origins
How is the Castle doctrine relevant? I jokingly expected sleepwalking to be an exception to the idea that a natural right existed to kill a robber or other home invader. But, I saw no mention of sleepwalking...
That citation starts with Exodus 22:2-3 saying: "it's OK to kill someone who invades your house" (I read: sleep) "during the night, but not ok during the day" (I read: awake). Also, re. castle doctrine: if you interact with someone in their sleep, and if they irrationally choose to be dangerous, they have no duty to retreat.
No duty to retreat: not because they're (sleepwalking) in their own house, but because they're unconscious (irresponsible, incapable of 'mens rea').
An example from the news, of someone waking up their co-pilot: Groggy Air Canada pilot ... caused injuries in jet dive: report.