During a period of extreme stress in my life I took Ambien about 5 nights out of 7 for 3 weeks.
Almost exactly 15 minutes after I took it, it was like someone flipped a light switch and I was out. This is why you DO NOT do anything but get into bed after you take that pill.
Exactly 7.5 hours after I took an Ambien I woke up. Again, it was like flipping a switch. I experienced no lingering drowsiness, but your mileage may vary. You can experience that side effect, but not everyone does. I think they tell you “be able to devote 8 hours to sleep” so no one gets the idea that you can schedule four hours of sleep with this. You can’t. It lasts about 8, but I suspect if you normally only sleep 7 hours a night that’s likely what you’ll get. And if you normally sleep 8.5 or 9 you might wind up doing that. Note, that is your normal, natural sleep requirement, not the Corporate Warrior “I can live on 4 hours a night forever with enough Starbuck’s coffee for breakfast” sleep pattern.
I didn’t do any sleep eating, sleep cooking, sleep driving, etc. I just slept. This is good, really, since that was the whole point of the taking the drug. The first few nights the spouse kept watch over me, hid the car keys, etc. just in case but in my case all it did was make me sleep.
The spouse did try rousing me after I feel asleep under the influence, just to see if it was possible. I have no recollection of it, but according to him, he was able to rouse me sufficiently so that if, god forbid, there had been some emergency he could have gotten me out of the house or whatever. I probably wouldn’t have remembered such an excursion, but that’s a different question.
So, for me, Ambien worked very well for its intended purpose and with minimal side effects. Then again, I only took for a short while under very specific circumstances. As always, consult your doctor, your mileage may vary, and so forth.