How to send a good night text message to a girl?

Have had similar experiences.

First of all, you can ask her to go for a walk at night, which will help her sleep and communicate.

Then, give her some soothing sachets or the like. Remind girls to drink some milk before going to bed.

When communicating via text messages at night, just don’t say too exciting things. Just send text messages as you normally would.

If she tells you to sleep, just sleep. Don't think too much. Just pay more attention to it.

Hope it helps.