We had one individual who was dreaming that he had injured a deer and was going to kill it by snapping its neck, and he was awakened as he was trying to snap his wife's neck. Both sleepwalking and REM sleep behaviour disorder have been used in court cases, with varying degrees of success, as an excuse. And it's an interesting situation, because clearly, potentially violent and illegal behaviours can occur during the sleep period. On the other hand, this would be a handy defence if someone might want to use to get off the hook for an intentional or volitional act. And the answer to the first question is almost always yes.
People can perform extremely complex behaviours in the sleeping and therefore irresponsible state.
For people who have potentially violent or injurious behaviours during their sleep, then we suggest that they have a sleep study. Because there are a number of conditions that can cause these behaviours, and usually with a combination of the history and the results of the sleep study, we can come up with a specific diagnosis that leads to, in effect, a treatment recommendation. For the two most common parasomnias, the first being the disorders of arousal, like sleep walking and sleep terrors, those can be treated either with medication or with hypnosis. The medication is generally Clonazepam, which is a benzodiazepine. Which is a sedative-hypnotic and can be very effective.