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Sleep Is the Ultimate Brainwasher
sciencehabit writes "Every night since humans first evolved, we have made what might be considered a baffling, dangerous mistake. Despite the once-prevalent threat of being eaten by predators, and the loss of valuable time for gathering food, accumulating wealth, or having sex, we go to sleep. Scientists have long speculated and argued about why we devote roughly a third of our lives to sleep, but with little concrete data to support any particular theory. Now, new evidence (abstract, full text paywalled) has refreshed a long-held hypothesis: During sleep, the brain cleans itself."
During sleep, the Cerebrospinal fluid fills channels in the brain, collecting waste products. It uses a lot of energy, leading to the hypothesis that the brain can't clean up waste while also processing sensory input.
I wonder how well this accounts for the extremely variable sleeping periods of various animals? See http://faculty.washington.edu/chudler/chasleep.html .
Many neurological diseases—from Alzheimer's disease to stroke and dementia—are associated with sleep disturbances, Nedergaard notes. The study suggests that lack of sleep could have a causal role, by allowing the byproducts to build up and cause brain damage. "This could open a lot of debate for shift workers, who work during the nighttime,” Nedergaard predicts. "You probably develop damage if you don’t get your sleep."
Beta amyloids are specifically mentioned, those make up the plaques that are found in Alzheimers.
Worth pointing out that the effects of sleep deprivation are well known, this is simply trying to explain HOW those symptoms occur.
I went almost a week without sleep and it definitely screws you up. On day 5, I was hallucinating that there were people around me and seeing things out of the corner of my eye. I had a constant fuzzy feeling and had very little energy. It was an interesting experiment and it was not easy to get to sleep. It took me over a month to get back into a proper rhythm.
Der Tod ist der einzige Weg hier raus!
A higher order species that has brains that can "cleans" itself without requiring sleep would have so much evolutionary advantage that they would rapidly take over the entire planet (sort of like flowering plants). Why hasn't 3+ billion years of evolutionary produced such a species?
I agree that it doesn't seem like night or day would matter much.
The second point, you're responding to a new hypothesis put forth by the researcher based on the current findings. The current findings are only that it's cleared out during sleep, not saying that low neural activity is the reason. That part is just speculation. I'd suggest it's probably more complex, that the glial cleaning activity causes abnormal neuronal activity when it's in that mode. Perhaps the reason it happens during sleep is because if it happened while you were awake, you'd hallucinate, act even more irrationally and irregularly etc. Perhaps that's part of the reason that dreams are so bizarre. Pure speculation.
Remember how Defrag in Windows 98 used to move the little colored blocks around? One night I got more or less the same thing. When I was about 11, several years before Windows 95 existed, I dreamed I walked into an M/E Root Beer restaurant (apparently a fictional counterpart of A&W restaurants) and in the back room, an anthropomorphic rabbit was sorting a bunch of pieces of paper with pictures on them into various piles. I looked at a few of them, and they appeared to be my memories.
I'm still convinced that dreams are artifacts of calibration routines, and only race conditions allow you to remember them.
Not that I remember. It was rough for the first two days but by day 3 I just didn't feel like sleeping anymore. I watched TV or played games all night until people were alive again and continued on with my day. I was exhausted though both mentally and physically somehow. The day after I finally slept was probably the worst. Still no energy but now coupled with nausea and no appetite. It was like a withdrawal of some sort... not recommended :P
I already kick into REM sleep really fast as it is so when I was not sleeping, I would sort of dream while being awake. It's a crazy experience for sure.
Der Tod ist der einzige Weg hier raus!
A few rare people can achieve a REM-like state while awake. I am one of them. In my case, I learned to do it due to having a lifelong hereditary sleep disorder. Going without sleep for up to five days is a common occurrence. I enter a trance state and begin to dream. I have more control over these dreams than during normal sleep but, I am mostly unaware of my environment though it is not hard to snap me out of it. I'm aware enough that if my name is called or someone touches me, I come out of it. On rare occasions, the dream state does not end right away and I have both stimuli at the same time. It is awkward but, navigateable. The state give me most of but, not all of the benefits of real sleep. My mind responds as if rested, it stops dulusions that occur because of sleep loss and the general mental slowdown that naturally occurs. What it doesn't do is some of the more complex physical cleaning that the body does when you sleep such as clearing substance P from your pain receptors. As I have fibromyalgia, this last point is very relevant.
"Be particularly skeptical when presented with evidence confirming what you already believe." -