Sleep to Learn

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Researchers are finally able to see what happens to specific neurons before and after periods of sleep and extended wakefulness. Cognitive decline is apparent in those who have not slept well, but the mechanism has not been well understood. It now appears that disordered sleep and chronic insomnia could actually be causing neuronal loss and damage. The hippocampus seems to be the primary area of concern, but other losses were noted in the thalamus and some others that I can’t recall but were super important for cognitive function, learning, memory, and behavior.

How many hours do you sleep each night? 7-9 is still recommended. I laugh at this number personally, thinking I could achieve that as easily as I could run a two minute mile. Or grow wings and fly. I’m a disordered sleeper, one of the many that struggle to get quality rest each night. I could give you names for why, but it doesn’t really matter what the label is. The outcome is that I have trouble falling asleep asleep, have trouble staying asleep, and experience horrific nightmares or spasms when I am asleep. Some days I am so sleepy I could fall asleep anywhere, like the fella in the pic above. But it won’t be for long, and it will never make up for all of the lost sleep and damage my tired little neurons have already suffered.

I have slept poorly for about 40 years now. It has taken its toll on my tired little neurons. More on this to come, but for now, here is some cool research on this topic.

https://go.aastweb.org/Resources/PDF/A2Zzz19_3/NeuronalLoss.pdf – “MRI scans detected no brain pathology among the study participants. From the scans, Riemann and colleagues measured each study participant’s total brain volume and the volume of the following brain areas: the prefrontal cortex, the orbitofrontal cortex, the anterior cingulate cortex, the amygdala, and the hippocampus. These structures play a role in memory, affect and decision-making. Riemann found that subjects with primary insomnia had a significantly smaller hippocampal volume than the controls. Since the subjects had no psychiatric disorders, Riemann concluded that the brain structural changes are associated with insomnia alone and that insomnia may either result from, or contribute to, brain structural changes. Ellenmarije Altena and colleagues in their recent study were the first scientists to demonstrate that the magnitude of brain structural changes is associated with the severity of insomnia.”

https://www.pennmedicine.org/news/news-releases/2014/march/penn-medicine-researchers-show – “Mice were examined following periods of normal rest, short wakefulness, or extended wakefulness, modeling a shift worker’s typical sleep pattern. The Veasey lab found that in response to short-term sleep loss, LC neurons upregulate the sirtuin type 3 (SirT3) protein, which is important for mitochondrial energy production and redox responses, and protect the neurons from metabolic injury. SirT3 is essential across short-term sleep loss to maintain metabolic homeostasis, but in extended wakefulness, the SirT3 response is missing. After several days of shift worker sleep patterns, LC neurons in the mice began to display reduced SirT3, increased cell death, and the mice lost 25 percent of these neurons.”

http://www.jneurosci.org/content/36/8/2355.full – “The raw behavioral data for the Mnemonic Similarity Task, for each of the three experimental conditions, are presented in Table 1. To first assess the impact of sleep deprivation and recovery sleep on hippocampus-dependent learning, a repeated-measures ANOVA was performed across the three conditions for the behavioral learning measure. A significant main effect of condition was identified (sleep-rested/sleep deprivation/sleep recovery) upon learning (F(2,28) = 21.47, p < 0.001; Fig. 2). Planned comparisons confirmed the expected condition impact of sleep deprivation, resulting in learning impairment relative to the sleep-rested condition (t(14) = 4.90, p < 0.001), consistent with prior studies (Yoo et al., 2007; Van Der Werf et al., 2009). Furthermore, a significant restoration of learning was observed following recovery sleep (t(14) = 5.38, p < 0.001), returning to performance levels that were not significantly different from those of the sleep-rested condition (t(14) = −1.09, p = 0.29). Thus, sleep deprivation significantly impaired hippocampus-dependent learning, while a recovery sleep period demonstrated the ability to restore learning ability.”

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