I've done 2 separate sleep studies in my life and both times apnea was ruled out. My B/P hovers around 122/74 usually and I take no meds other than Ambien and Lexapro. Lexapro doesn't affect the sleep because I had insomnia issues before and after I was on it. I'm out of Ambien though and it's killing my sleep. As for narcotics/benzos and respiratory depression, my body has dealt with much more powerful drugs without a problem (Dilaudid, Ativan, etc).
I've simply been a terrible insomniac since my earliest memories (4 years old), and only 20mg of Ambien a night seems to help--but even then I need to take a week off of that every month so my body doesn't build up a tolerance to it. I exercise regularly, generally eat well, and have stopped the recreational drugs.
I simply cannot sleep.