Can sleepwalking really overcome survival instinct?

I’m wondering if the stories I’ve read about the more extreme things sleepwalkers do are true. Specifically, I’m talking about tales of sleepwalkers murdering others, mutilating themselves, and committing suicide in their sleep.

(In case you’re wondering about how you’d know in the last case, I read an anecdote once about a man who cut his throat. His last actions as he bled to death was to signal for a piece of paper and pen, with which he wrote, “I dreamt that I was killing myself. I awoke to find it true,” or something like that.

Possible? Exaggeration? How deep a sleepwalker would you need to be to completely overcome conscious morality and survival instinct? Heck, if it’s possible, I’d like to try writing a story in which a straight man has gay sex while sleepwalking!

One of my friends went sleepwalking right off a seventh story hotel balcony. That was long before I met him, but his wife told me about it. I don’t know how much damage was done at the time, but it’s amazing that he lived. The only residual effect that is noticeable is a lack of clarity in his speech. There’s nothing wrong with his mind though!

Zoe: Yes, but I’m not sure I really count cases like that. Your friend wasn’t violating survival instinct; he simply thought he was walking somewhere safe (probably). Whereas there’s not many ways that I can think of to dream that you’re slitting your own throat, actually DO it, and NOT realize it, you know what I mean? And how deep a 'walker was he?