[jklp]

I remember watching this TED talk a couple years ago which stuck with me, though am not 100% sure on its validity.

http://www.ted.com/talks/jeff_iliff_one_more_reason_to_get_a...

The theory being that sleep was a way to clear out waste from the brain during normal operation, due to the lymphatic system not extending to the brain, it has to put itself into "sleep mode" to drain the waste.

This might explain why memory is usually better after a good night's sleep, and also the cause of dreams - which is just misfiring of neurons while the waste is being cleared.

[fian]

So sleep is something like garbage collection in Java? Some perceptions/thoughts you experience during the day need to be mived from a finite sized young generational heap to a long kived heap (ie convert important short term memories to long term memories). This then frees uo space in the young gen. heap for the next day. Dreams could potentially be the result of a reference check being performed to see which memories to move to a different heap and which can be discarded.

[spyder]

It's already in the article:

"Neuroscientists discovered a previously unrecognised network of vessels in the brain that flush out the fluids between brain cells: the “glymphatic system”."