>>11
1) Did you not read the wikipedia article? We don't yet know what exactly the original purpose of sleep is for. It has only been in the last 5-10 years or so that we've actually made progress in understanding it.
2) You seem to be confused. Natural Selection does not work that way. There are no "solutions" in Natural Selection. Everything currently existing is merely the result of what has worked "good enough" for a species to survive with. The actual evolution of those features is a series of genetic accidents and not every change is for the better, nor is anything necessarily efficient.
3) As happens so often in Evolution, sleep has probably acquired additional purposes than what it was originally "developed" for. The observed memory functions could be indicative in this adaptation in species with larger brains. The original purpose may even have already been rendered unnecessary long ago by another process.
4) Not every species that sleeps is helpless and unaware of their environment. Traits like unihemispheric sleep (only one side of the brain is asleep) are quite common in birds and aquatic mammals. Other species have developed sleeping behaviors such as nesting that protects them (or gives them ample warning) from predators. Social species rarely all sleep at the same time, essentially having "gaurds", etc.
5) You haven't given an alternative "solution". Considering no one even knows what the "problem" actually IS, that isn't surprising. Since you don't know the reason and you obviously don't know what you're talking about in a larger sense, none of your arguments are valid.
6) Regarding your claim about testicles, perhaps you should read this:
http://en.wikipedia.org/wiki/Testicle#External_testicles
External testicles are not the norm by any stretch of the imagination. Only a relatively few species have external testicles.
And the previous point applies. That is, all the "criticisms" I've seen against the temperature regulation hypothesis have been arguments from personal incredulity, a logical fallacy. Simply saying it isn't a "satifactory explanation" is not a valid argument. As I've said, Natural Selection and Evolution do not work that way.
Anyway, there are two other major hypotheses as well. Read the article.