[coss]

I feel like there must be some way to 'clean' our brains. As we get older it must accumulate 'gunk' that slow it down or weaken connections.

I guess sleep is the closest thing we have but to me that's like saying drink water to fix tooth decay.

[Bluestrike2]

We already do (in a multitude of ways) when we sleep. There's research that indicates that sleep is used to clear away neurotoxic waste.[0][1] The role of deposits of tau and beta-amyloid proteins in Alzheimer's[2] and aging are also of particular interest. Other papers supporting the synaptic homeostasis hypothesis suggest that sleep is when synaptic strength is renormalized.[3][4] Basically, memories are reinforced (the signal) in relation to existing knowledge while daily noise is effectively pruned (among other processes).

The analogy is flawed, but the brain already has some pretty intricate garbage control methods. As we learn more about them, it'll open up new paths for clinical treatments for a host of problems.

0. https://www.ncbi.nlm.nih.gov/pubmed/24136970

1. https://www.nih.gov/news-events/nih-research-matters/how-sle...

2. http://www.sciencemag.org/news/2018/01/alzheimer-s-protein-m...

3. http://science.sciencemag.org/content/355/6324/507

4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3921176/

[BLKNSLVR]

Taking your question conceptually, rather than physically, memories / experience would be 'gunk' if they're outdated (don't relate to how the world works anymore, or don't relate to how your body works anymore).

Your memories and experiences (potentially one and the same) colour your experience of the world and make you react in different ways, not always beneficial - but the phenomenon wouldn't exist if it wasn't historically, evolutionarily beneficial.

[rmwaite]

Drinking water (instead of sugary and/or acidic drinks) is actually a very good way to prevent tooth decay.

[Retra]

Even if you drink sugary/acidic drinks, water helps dilute them and rinse them away.