Final answer:
The nurse is demonstrating the therapeutic communication technique of restating.
Step-by-step explanation:
The nurse in this situation is demonstrating the therapeutic communication technique of restating. Restating involves repeating or summarizing the client's words to show understanding and encourage further discussion. In this case, the nurse restates the client's statement about difficulty sleeping. This technique helps to validate the client's feelings and encourages them to continue expressing their thoughts and concerns.