Hi,
I was on nitrazapam on and off for about a year before ttc and when I spoke to the doctor he said that it isn't worth the risk as it stays in your system for a few days. In saying that, your GP might allow you to have something for the week you were on your period, at least then you know every three weeks you can catch up a little and that in itself will take away the anxiety of 'will I ever sleep again'. Thankfully in my case, after 6 years of sleep deprivation on and off I am sleeping fine now. I guess mine was mainly stress related (ex husband lol) followed by a fear of not sleeping. It is horrible isn't it and so I hope you find something that works for you.