>> We know about things unimaginably distant in scale or time -- like quarks and the Big Bang

Oh, we do?

That's funny, Afaik quarks still confuse physicists because they behave erratically and appear to be composed of other particles. And the big bang is simply an assumption that makes the cosmological model work well for our human brains, but it is not how the universe started specifically.

We don't know jack shit, that's the bottom line, and we like to pretend we do.

"We live in a culture of casual certitude. This has always been the case, no matter how often that certainty has failed. Though no generation believes there’s nothing left to learn, every generation unconsciously assumes that what has already been defined and accepted is (probably) pretty close to how reality will be viewed in perpetuity. And then, of course, time passes. Ideas shift. Opinions invert. What once seemed reasonable eventually becomes absurd, replaced by modern perspectives that feel even more irrefutable and secure—until, of course, they don’t."

http://www.goodreads.com/book/show/27068734-but-what-if-we-r...

Yes. We were, are and will always be living in "modern times"...

You might consider the The Relativity of Wrong:

http://chem.tufts.edu/answersinscience/relativityofwrong.htm

Sure, maybe we know jack shit. But we know unfathomably more jack shit than in previous ages.

> That's funny, Afaik quarks still confuse physicists because they behave erratically and appear to be composed of other particles.

I'd really like a source for the composite quark claim.

Well, String Theory.

Couldn't have given a worse answer.

1. String theory has no experimental backing.

2. It doesn't posit that currently fundamental particles become composite.

For a decent explanation see:

https://physics.stackexchange.com/questions/38767/relation-b...

What evidence is there for quarks being composite?

I think it is because of a few interrelated things:

1. Ill-posedness of the problems: what is sleep?, why do animals sleep?, etc. vs. the well-posed physics problems such as, what happened at the beginning of the universe?

2. Data sufficiency: there is too much variability across people and animals to have enough representative data marginalized on each variable for many biological systems in general, and sleep in particular

3. Complexity of the system: cosmological systems and even subatomic particles are less complex models than biological systems

On incentives for researchers, there is also the maxim that there are many unsolved and interesting problems to work on, but scientific judgement is in knowing which are solvable. Of course, the occasional maverick goes after the hardest, most ill-posed, most unsolvable problem. But the existence of such mavericks is not guaranteed for every problem, sleep biology included.

Brain is very active when you sleep, a lot is happening. Imagine sleep is just a mutex on big set of data on which computation needs to be made, compression, data reorganization, index optimizing. Data that you received that day is segregated , decisions are made which data to keep and which to delete. After that lock is freed and you wake up. If you don't sleep your system will run slower and slower over time and will timeout more and more queries until it will start to return corrupted data. You need to sleep to keep the system healthy.

That is a theory. There are many other theories too. The OP's observation was that we don't really have a firm grasp on which theory or theories is/are correct, in the way we (believe) that we understand something like the nature of chemical interactions, or the limits of finite-state computation. Sleep, like many many other functions of the brain, not the least of which being its most recognizable function (to us), remains something speculated about without broad consensus. As per the fantastic quote in the linked wiki article,

"As far as I know, the only reason we need to sleep that is really, really solid is because we get sleepy."

A theory, sure. Another thing to remember about biological systems is that complex features like sleep rarely serve just one purpose. There will generally be one cause that was killing lots of members of a population which the feature was developed to mitigate, but other "reasons" may have grown over time as evolution "discovered" other ways the feature can help.

I think in general, good-sounding theories produced by the "speculative evolutionary biology" game are actually very often right -- but only describe one facet of a supremely messy system with boundaries that don't conform cleanly to the mental models we try to impose.

Sure, but that's just pure speculation.

Sleep = vacuum freeze analyze

Garbage Collection

We need a concurrent GC.

It's called Red Bull. It gives you wings. Nature is now selling native advertising.

A better way of posing it might be to say that we don't know why the stuff accomplished during sleep can't be accomplished during wakefulness. We do know that the purpose of sleep is to maintain pretty much everything.

Sleep does more than one thing. One advantage is lower energy needs, so saying we don't know what it does is very misleading. We don't know Everything sleep does in Every situation, but the same is true of everything else.

Scientists still don't understand the mechanisms behind lightning formation! Turbulent flow is also another great unsolved physics problem.

You might call this bias of similar scales: things that happen within our attention must have similarly brief explanations.

It's meant to separate days. That way each day is a new day, and you have some sort of mental partition between each one.

What purpose does that serve? Why would it be more advantageous than a continuous time stream?

We don't have similar separation between morning & evening, for example. (though I've always been a fan of the siesta)

Its meant to serve physiological homeostasis in some way yet to be completely understood :)

as someone who has had a rotating schedule their entire life, I wonder what that would mean for my brain.

What do you mean by your "entire life"? Since you were an infant? I have non-24[1], but it didn't manifest until I was in my 20s.

[1] https://en.wikipedia.org/wiki/Non-24-hour_sleep-wake_disorde...

meant by who?

Whoever you want.