I am so sorry that a Dr. would prescribe this class of drug for insomnia. Were you diagnosed as psychotic, bipolar, or something else? This class of drugs are called antipsychotics. When we need quality sleep, there are plenty of sleep aids available that are quite effective - Ambien, Sonata, etc., to name a few.
Who is rx'ing this drug to you? If you want to get off of this, I suggest you find another physician, hopefully a well qualified psychiatrist, who will help you in the withdrawal.