REM sleep
Article
REM sleep is a recurring concept in the Astral Codex Ten archive, appearing 2 times across 2 issues between March 16, 2021 and May 13, 2022. The archive places it in contexts such as “What is the role of REM vs. non-REM sleep? Depressed people have much more REM sleep than non-depressed people”; “In dream phases (REM sleep), external stimulation usually does not spark consciousness”. It most often appears alongside Giulio Tononi, Scott Aaronson, Alaska.
Metadata
- Category: Concepts
- Mention count: 2
- Issue count: 2
- First seen: March 16, 2021
- Last seen: May 13, 2022
Appears In
Related Pages
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- Giulio Tononi (2 shared issues)
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- Scott Aaronson (2 shared issues)
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- Alaska (1 shared issues)
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- Are We Smart Enough To Know How Smart Animals Are? (1 shared issues)
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- Astralcodexten (1 shared issues)
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- attention (1 shared issues)
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- BERN (1 shared issues)
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- Bundespräsident (1 shared issues)
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- Chronotherapeutics Manual (1 shared issues)
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- conscious access (1 shared issues)
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- conscious perception (1 shared issues)
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- Consciousness and the Brain (1 shared issues)
External Links
Source Context
Recovered passages from the original issue text. When the raw archive preserved outbound links inside the source passage, they are listed directly under the quote.
What is the role of REM vs. non-REM sleep? Depressed people have much more REM sleep than non-depressed people. Serotonin seems to decrease REM sleep, so unsurprisingly SSRI antidepressants decrease REM sleep a lot (not just in depressed people, in everybody). This would lend itself very nicely to a theory where REM sleep is involved in decreasing synapse strength, depressed people have too much of it, they end up with overly weak synapses, and that's what depression is. In this model, antidepressants would treat depression by increasing serotonin levels in a way that represses REM. The problem with this is that in Tononi's original paper, he says that the best evidence supports synaptic renormalization in non-REM sleep; he doesn't have a great idea what REM is doing. He does mention one possibility is that non-REM sleep renormalizes most of the brain, but for some reason it doesn't work on the hippocampus, and REM sleep renormalizes the hippocampus. And some of the studies on depression and synaptic density point to the hippocampus in particular. But others don't, and this connection seems kind of forced. I think R&K mostly focus on slow-wave sleep and think it's renormalizing incorrectly rather than just too much or too little.
Inline links: decrease REM sleep a lot, original paper
How does this relate to circadian rhythm? We know disturbances of the circadian rhythm - when your body expects day vs. night - are heavily involved in depression, especially seasonal depression. We know circadian rhythm changes sleep architecture, altering the balance between REM vs. non-REM sleep. Is this why it has such a strong effect on depression? Maybe if we could figure this out we would have a better sense of whether it's REM vs. non-REM sleep which is the issue here.
Inline links: especially seasonal depression, changes sleep architecture
Now that we understand consciousness, we have quite a lot of tests to tell apart conscious from unconscious processing. Indirect clues come from abilities. It seems that working memory requires consciousness, and Dehaene has developed some very detailed tests to decide whether someone is conscious. Not just for fun; he works with patients in long-time coma (more precisely, in vegetative state). Some of them are fully conscious locked-in patients, but this is quite hard to detect. Dehaene has developed tools for detecting traces of consciousness in such patients, and they can predict (to some extent) whether the patients will eventually recover. They are also useful for developing communication devices for locked-in patients. But we can also apply the tests to healthy individuals and see what we get. We are not conscious during anesthesia (what a surprise), but sleeping is already more complicated. Most sleep phases are unconscious. In dream phases (REM sleep), external stimulation usually does not spark consciousness. However, the brain does react like a conscious brain if the stimulus is directly implanted into the brain via magnetic stimulation (TMS). So perhaps we are conscious in dreams, and we are only cut off from outside perception. But it is too early to be certain. Also, although the book does not discuss this point, I wonder whether we are conscious all of our daytime. Probably we don't use the full bandwidth of two conscious perceptions per second the whole day. How conscious are we when we enter the "flow" during a marathon? Can meditation suppress consciousness? I don't know.