What is when a guy asks how did you sleep reply?

When a guy asks how did you sleep, it means that he is showing concern about your well-being and is interested in knowing how well you slept the previous night. It could also be a way of wanting to start a conversation or make small talk. It's important to give a genuine response and share any issues or concerns that may have affected your sleep. It can also be an opportunity to share any good experiences or pleasant dreams you may have had. Overall, it's a casual way of showing interest and starting a conversation.