You have asked an interesting question, but with little background information about how long she has done this, whether she does this every evening or occasionally. Is it during the week or only on weekends? Is she eating or just standing? Is it early in the evening or in the middle of the night after she has been asleep. Is she having sleep problems? It is possible that she might be needing quiet alone time to think about something? Has she been under stress? Has she had emotional problems?
It is hard to know why she is doing this without knowing more. You might want to do a little investigating.
The simplest way to answer to your question might be to ask your daughter about this behavior. You might be able to find out what is going on with a brief conversation. Be sure to use a gentle, no-shame approach, maybe best when she is not doing it. I am not sure that approaching her in the dark kitchen with, "What are you doing in here?" would get you the most effective response. However, gently coming to her in the kitchen with a non-confrontational question, such as, "Is something on your mind?" or "Are you having trouble sleeping?" might work.
What I would recommend is to try approaching her when she is not standing in the kitchen and asking questions like these: "I have noticed that sometimes you are standing in the kitchen in the dark. I am curious about why you are doing this? Can you tell me a little about this? Is it helping you in some way? Is there something bothering you that you would like to talk over?
Be on notice that she may not be able to tell you; she may not want to tell you;or she may not know herself. If that is the case, you might say something like, "Well, it is okay if you do not care to talk about it now, but I would like to
know if something is on your mind, so let me know if you want to talk another time."
Once you do this, if you still have questions, write us back and tell us a bit more.
Some of the savvy and wise Education.com members might have some other ideas.