I almost never use an actual alarm (when I expect one to go off, it makes me sleep fitfully) but when I've been woken up and don't have to get up yet, I can fall into a light doze which leaves me pleasantly conscious of being comfortable and relaxed in a way that being outright asleep does not. I don't think I'd take a magic pill that caused me to be instantly alert and energetic on waking if I couldn't have that dozing period for at least a few minutes.