I was prescribed Zimovane (Zopiclone) for a short while a few months ago to help me fall asleep: the first and hopefully last time I tried sleeping tablets. It is phenomenally effective: one pill and I was sound asleep within half an hour, and awake the next morning feeling alert and much more refreshed than normal. Therefore, I strongly suggest you never try it if you have even the slightest disposition to addiction.
The only downside was a strong metallic taste in the mouth until early afternoon.
From your description of your sleep patterns I'd guess it's just a sleep/stress thing. Daily or near-daily exercise may go a long way towards aiding you sleep.