What could cause frequent nocturnal urination?

Many causes: Peeing at night can be caused by many different things. The first thing to do is keep a bladder diary for a couple days. This will help your provider when you see them for this problem. Here is a link to a bladder diary. Fill it out for 2-3 days before seeing a urologist. (http://kidney.Niddk.Nih.Gov/kudiseases/pubs/diary/index.Aspx).