I have a similar reaction with temazepam - it keeps me awake.
I would tell your GP how it reacted as there are afew other options - its like any drug, some peoples bodies are better with one than another.

On the original q, yes I have the same problem, when DH is not home becuase he is at a gig or interstate I stay up til all hours until I am ready to collapse. Im worried at how this woll work when bub 2 comes along though