Final answer:
The nurse is demonstrating the therapeutic communication technique of restating.
Step-by-step explanation:
The nurse is demonstrating the therapeutic communication technique of restating. Restating involves repeating the client's statement in the form of a question, which encourages the client to elaborate and clarify their feelings or thoughts. In this case, the nurse restated the client's statement, 'I can't sleep. I stay up all night,' by saying, 'You are having difficulty sleeping?'