is a stimulant and can cause sleep disturbance. Melatonin
does help in sleep restoration. But along with medications you should always try all the sleep hygiene
measures. Firstly stop all tea/coffee/alcohol/chocolates/colas as all of them contain caffeine. Next you should start with daily exercise for 45 min to 1 hr. Take a warm bath at night, regularize sleeping timings. Dont try too hard to go to sleep. If not getting sleep, sit up, do some reading and again go to the bed when you feel drowsy. Use your bed exclusively for sleeping and keep bedroom lit dim. Any psychiatric medication will take time in acting and you should avoid switching psychiatrist
in short time.
If the problem still persists there could be a possibility that you might be having a co-morbid deprsion and in that case you should be taking an anti-depressant along with your sleep medication
Hope I am able to solve your concerns.