Comment by hn_throwaway_99 | Hacker News Reader

Comment by hn_throwaway_99 | Hacker News Reader

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hn_throwaway_99

As a Gen Xer, the relatively recent discoveries around the purpose of sleep are pretty fascinating to me. Throughout most of my life, we basically didn't know why we need sleep. It's very clear we (and essentially all vertebrates) do need sleep, but we really didn't know why.

Now we basically do: sleep is when you clear out waste products in your brain. As someone who definitely doesn't understand all the details, it's when "channels" it your brain get opened up so these waste products can be swept away. This study (based on the title) claims to show the mechanism for doing that:

1. Norepinephrine-mediated: norepinephrine is a neurotransmitter, so this is saying it's responsible for the mechanism of action.

2. slow vasomotion - you can Google what vasomotion means, but it's essentially a rhythmic change it the walls of blood vessels - this is essentially the "sweeping away" part I mentioned above.

3. glymphatic clearance - the glymphatic system in the brain is that network of fluid filled spaces in the brain, and it's what clears away brain waste products, so glymphatic clearance means allowing the glymphatic system to "wash away" those waste products.

So, this study claims to explain the mechanism by which waste products get cleared from the brain during sleep, and the larger context is that it is indeed why we need sleep in the first place.

I'm also squarely GenX. While studying mechanical engineering, one of my roommates was in psychology. He said "we" didn't need sleep. He said one of his professors told them that. I said, "But we ALL do it." He said it was just a convenience thing.

To his credit, he decided to test his theory. By not sleeping. During FINALS WEEK. He said, by the third day, he saw Tom Sawyer and Huck Finn walk across the pages of the book he was reading, and decided it was time to take a nap.

But, hey, I tried smoking banana peel, ala the Anarchist's Cookbook, so I don't have any room to talk.

Even before I went to college I knew that Race Across America winners would sleep only a couple hours a night, timed to wake at sunrise to trick their brains into thinking they’d gotten more sleep. They’d be hallucinating by the end, which did not sound like fun.

I think the longest I ever made it was 70 hours. Maybe 80. I had two finals on consecutive days so I stayed up to cram for the second. Fibbed to my parents about when I was available to come home for the holidays, so I went to the computer lab to binge games with a couple friends, never made it to sleep that night.

I went to bed when the blue background on the computer terminal started to swim. That’s enough internet for me today.

The older you get the more dangerous it is to do this. You can start dying sometime between 70 and 120 hours. And the quality of whatever you’re doing is declining rapidly after 30 or so. Go to bed.

Another big learning from this is that "not all sleep is created equal." What happens during NREM isn't the same as what happens during REM.

Which surprises me because I thought we were all taught that REM is the best kind of sleep (and the hardest to induce). But also doesn't Ambien reduce the amount of time in REM and increase NREM.

I'm confused again. Someone better educated than me care to explain?

Hmm, I don't know about Ambien, but I didn't hear that REM is the best kind of sleep. On the contrary, REM sleep is the sleep level just below being awake, while what you really need is deep sleep, and when you're in really deep sleep, you're not dreaming.

> sleep is when you clear out waste products in your brain.

It's unfortunately more complicated than this: we also clear out the same waste products in our brain during wakefulness. Mostly at a higher rate, too. Perhaps there's some unique way in which this happens during sleep but this certainly isn't the "key" (if there is in fact one) to why we need to sleep.

Your questions around why we need sleep make me wonder if we could develop a drug cocktail to do that work for us while we're awake. Similar to Iain M. Banks' "Culture" book series where humans can inject themselves with their "drug glands" to improve their capabilities.

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