I had the same problem and actually got a sleep test but they didnt find anything. I finally found a psychotherapist who specializes in sleep disorders- once u have a sleep disorder for awhile it leads to a vicious cycle of anxiety, which keeps you up at night. There are also sleep hygeine techniques that you can research online. Overcoming Insomnia: A Cognitive-Behavioral Therapy Approach Workbook (Treatments That Work) by Jack D. Edinger and Colleen E. Carney (Mar 27, 2008)
Good Luck