There are many causes of nocturia. The main cause is urinary tract infection (UTI) or excessive fluid consumption especially in the evening time. Some other causes are diabetes, overactive bladder, anxiety, organ failure such as heart or liver failure. Consult doctor for proper diagnosis.
Chewing Raisins before you hit the bed may help absorb any excess water from your vascular system, and delay the need for urination for quite some time.