Cyclobenzaprine hydrochloride is a commonly prescribed centrally acting muscle relaxant, which is structurally similar to tricyclic antidepressants (TCAs) and differs from amitriptyline by only one double bond.

In essence it is an antidepressant. The reaction you had would be a side effect of the medication. Also it's possible that you might be feeling some withdrawal effects. I would advise you to share here next time you have problems, e.g. with insomnia, and find out what natural remedies people recommend <img src="/ubbthreads/images/graemlins/smile.gif" alt="" />