I just got here. To add my personal experience with Ambien.

I can take one, maybe two Ambiens and it's likely I will fall asleep. I mix it with alcohol, I'll be fine, then pass out and remember nothing.
I take three Ambiens and it is like taking cocaine (not that I have, just descriptions). 3 Ambiens will knock me out cold for about 2-3 hours, then I bolt straight up, completely wired, desperate to crawl out of my skin, and I can't. I try everything, lotion, showers, scratching, nothing works. I eat trying the old wives tale that food will absorb the alcohol and medication. Nothing. Eventually, after wandering around the house, trying to watch TV, surfing the web, it calms down enough where I can go back to bed and lay down.

Sometimes these medications have the opposite effect when you take more than the prescribed dosage.

The same thing happens when you take Benedryl. The active ingredient, dyphenhydramine is an antihistamine which helps you with allergic reactions and a central nervous system depressant, which means it will make you sleepy and groggy. You take one, you can mostly function. You take two, you are out cold for 6 hours. You take 3, you get the same manic reaction I mentioned above. Crawling out of skin, rapid heartbeat, inability to stay still. You can accomplish the same miserable feeling by taking Benedryl with a NyQuil chaser. I learned this the hard way. I hate the discomfort of a cold. I thought if I had the Benedryl and the NyQuil together, I would have a restful sleep, my sinuses would dry up faster, I would be able to breath, and ultimately feel better.