How long have you been suffering from insomnia? Do you lead a stressful life? Do you exercise? These are some questions for you to answer and maybe need to change.
Try a couple of drops of lavender oil on a tissue and place it under your pillowslip. Apparently that helps to relax and bring on sleep.
Drink camomile tea, that assists also.
Have you visited a naturopath? There maybe also something that you are eating that indirectly brings on the insomnia.
Taking synthetic chemicals long term is not a good long term solution, you need to get to the bottom of the cause of the problem.