I have a fetish that I have found out is called somnophilia, or the attraction to sexual activity with a sleeping person. I have told this to my girlfriend and she has no problem with it, or with allowing me to fulfill my fantasy with her, since she is very submissive. The only problem is, she's an extremely light sleeper. As in, she wakes up at the drop of a hat. For this reason, there's really no way for me to do it naturally.
I have tried artificial methods such as OTC sleeping pills. However, these just make her drowsy, but don't affect her depth of sleep, ie. she still wakes up right away. So here's my problem. I am looking for either a method or a drug that will put her into a very deep sleep, or even leave her unconscious, such as you would be under the influence of a general anesthetic during surgery. I guess I would need a very powerful sedative/hypnotic. I have heard of drugs such as Rohypnol, but I know that these are illegal in the US, and I'm not trying to get into any trouble here.
I figured I'd try posting this here, since a medical site would offer me the benefit of people who know about drugs and how safe they are, since I don't want to risk her safety or health. I considered asking a pharmacist, but I'm worried they'd think I'm looking for a "date rape drug" for illegal purposes and call the cops on me.
Does anyone have any suggestions? To summarize, I'm looking for something that'll knock her out and will withstand a vigorous activity like sex.