Comment by cyberax
4 days ago
> Mitochondria are too universal and sleep is too specific to the brain
The brain has uniquely high specific power requirements per gram of dry weight. Not even the heart is this power-hungry. This surely places a lot of uniquely high metabolic stress on the neural cells.
And neural cells are long-living, so they can't be easily replaced throughout the lifetime. So their housekeeping has to be very thorough, carefully cleaning up all the waste products.
So this hypothesis actually makes a lot of sense.
Mitochondrial dysfunction literally leads to Alzheimers, dementia, etc. The link is clear as day - don't sleep, lose your mind. Put a different way, life rusts (oxidizes) your brain, and sleep de-rusts it. And unfortunately I'm still someone who regularly pulls all nighters because of a combination of disorders, ADHD and sleep cycle issues. I'm killing myself rather prematurely. But then, all addictions tend to do that and tend to be things the addict has trouble controlling. :(
Also, the theory would better be expressed as "all mitochondria require rest, neuronal rest in the brain looks like sleep (but many cells in the body also get quite a bit of rest during this time)" - so many people here seem to be getting this backwards thinking sleep is the special thing - it's one way large scale mitochondrial rest (as well as lots of other important co-occuring processes) presents in the brain.
The really interesting question is... how do heart cells do it? Because they're a clear exception to this theory... Lactate?
Maybe the heart can just handle the stress longer before something visible breaks? It has a simpler function than the brain, which probably helps. If people tend to die of cancer first (or whatever), the heart only needs to withstand about 80 years of gunk buildup to not be the weakest link.