I wouldn't say asinine but still some
loopholes which is normal for
evolutionary hypotheses. (And I would like to point out that,
YEAH!, the
Pragmatists &
Evolutionists have taken over the
teleological argument. Nyah-nyah.)
*cough*
Another idea is that sleep-attacks might just have simply selected for other characteristics: light sleep, improved hearing, better vision, habitat-matching fur/feathers/scales/etc. And, it is reasonable enough to say that a species switched from diurnal to nocturnal or the other way around due to evolutionary forces. All of these can be clearly driven by evolution.
Sleep, on the other hand, not so. The argument that an animal after sleep performs better is not answering the question. The problem here is that evolution "should" have selected for an animal that didn't sleep yet still performed. Since it didn't, there are 3 choices: 1) oops, 2) it's not actually more beneficial to survival, 3) sleep is über-evolutionary.
The correct answer lies presumably in (3) due to cellular biology/histology rather than evolution. The study of the daily rhythm in all organisms and, in fact, in every cell has been progressing. Apparently, there is an enzyme-feedback mechanism which approximates the day. This means a certain chemical is produced and builds up until it reaches a critical point where it is no longer produced. Then an enzyme breaks it down until a certain point at which there is so little that it is produced again. For the cycle to occur once is about 22-24 hours.
Though this isn't proof of sleep, these rhythms make it more more reasonable to assume that there's a natural need for sleep. I'm not saying I know the mechanism which requires sleep, but I would say that it's a much more basic necessity than an evolution-selected characteristic. The need for this energy renewal exists at the cellular level, and so is there to stay.