Amnesia.
From an interesting recent
NY Times article on how the mattress industry wants to get in on the act:
In one six-week trial, for example, people taking Ambien every night fell asleep, on average, only 23 minutes faster than those taking the placebo. They spent 88 percent of their time in bed asleep, as opposed to 82 percent. Given that their objectively measured improvements are frequently this meager, why do sleeping pills create incommensurate feelings of having slept so well?
A popular theory is that one of the pill’s side-effects is actually contributing to their success. Most sleeping pills are known to block the formation of memories during their use, creating amnesia.
I never feel more like I'm living in some sci-fi version of a dystopic future than when I come across a pharmaceutical ad while I'm out in public. Happened in the break room at work the other day. On a plasma screen tv. Tuned to the Fox News channel.