My twins have serious seizure disorder and take Valproic Acid (500mgs BID).
I have researched natural products as well to deal with sleep disorders and seizures and found Melatonin. Here is an article to read -
http://www.neurology-asia.org/articles/20043_114.pdf.
There are many articles on Melatonin and seizure disorder. This is one place I would start if you are looking for "natural products." It's the only one that I know of.