For many years, sleep has been treated as a soft topic in biology, more psychology than hard neuroscience. However, that view has been turned upside down. Researchers are now studying sleep at the cellular and metabolic level to find out how sleep actually works in the brain.

“Sleep is widely conserved across the animal kingdom, so there should be the same basic function across species,” said Amita Sehgal, a molecular biologist at the institute. University of Pennsylvania.

This evolutionary milestone has led scientists to rethink sleep as more than just downtime. Growing evidence suggests that it functions as a maintenance mode for the brain.

Helps protect your energy system, eliminate metabolic damage, and keep your neurons healthy. These changes may also help explain why sleep disorders often appear with diseases such as Alzheimer’s disease.

Sleep through the lens of a fly

One of Sehgal’s early contributions was Drosophila A full-fledged model of sleep biology.

This may sound strange until you remember the gist of model organisms. You need a simple system that allows you to clearly trace cause and effect.

Her team’s recent research points to the core idea that sleep is intimately connected to metabolism. More specifically, sleep may specifically protect the brain’s mitochondria (the cells’ power generators).

That’s a far-fetched claim, but the logic is pretty well-founded. When you’re awake, your neurons are constantly firing. Its activities are mitochondria.

The problem is that energy production produces reactive oxygen species that can damage mitochondria and the cells they live in. In other words, brain activity causes attrition as a side effect of business.

Sleep protects brain energy

Sehgal’s group found evidence that sleep helps keep neurons functioning by transferring some of the oxidative damage from neurons to glial cells, supporting and maintaining the nervous system.

Damage is transferred in the form of oxidized lipids. Glial cells then process these lipids in several ways. Some of it is broken down as energy, and some of it is passed on to cells. blood cell It has receptors designed to receive them.

The image that emerges is not that “sleep shuts off the brain.” In fact, I feel like sleep changes our cleaning and maintenance mechanisms, especially when it comes to energy use and damage control.

“In order for these neurons to function, they need a reliable, clean energy source inside them to function,” Sehgal says.

“One of the ways sleep helps keep neurons healthy is by moving these lipids around and removing some of the oxidative damage.”

Sleep to match your brain’s clean-up shift

Alongside research on mitochondria, Sehgal’s lab has also studied other processes that appear to be altered by sleep.

The overall theme is consistent. Sleep appears to be a time for the brain to process. metabolic And housekeeping your phone in a way that is completely impossible to do while you’re awake.

Her team linked sleep to autophagy, the cell’s system for recycling parts and regenerating worn-out components, including mitochondria.

The researchers also studied how sleep affects the movement of molecules between the brain and blood across the blood-brain barrier.

The researchers looked at neuromodulators (chemicals that can increase or decrease the activity of nerve cells) and found that they change in response to changes in sleep, even though they are not necessarily the root cause of the need for sleep.

When you sleep less, your brain compensates.

The lab also linked feeding states to the types of memory the animals relied on, finding that sleep-dependent and sleep-independent memory use changed depending on whether the animals had eaten or not.

Taken together, these lines of research support the same basic hypothesis: sleep is driven by metabolic needs. The idea is that when you sleep less, metabolic waste products build up and your neurons can no longer function at full capacity.

When mitochondria within neurons become strained or damaged, the brain’s energy supply becomes less reliable. And everything downstream begins to wobble: attention, memory, resilience.

“We’re really excited about the research right now,” Sehgal said. “I feel like we’re really starting to solve the whole sleep problem.”

Sleep, Alzheimer’s disease, and mobile phone links

Sleep research is not just about solving universal mysteries. It also leads to real health problems.

including many neurodegenerative diseases alzheimer’s diseaseoften accompanied by sleep disturbances. Although the direction of cause and effect is complex, Sehgal’s work highlights a plausible bridge. Some of the cellular systems affected by sleep are the same systems that cause problems in neurodegeneration.

Two examples are lipid metabolism and autophagy. Sehgal’s lab has shown that both are regulated by sleep. Both are known to be involved in neurodegeneration when dysfunctional, and both become dysfunctional in patients with Alzheimer’s disease.

Her team discovered that in flies, damage can be transmitted from neurons to glia via lipid carriers similar to apolipoprotein E (APOE).

In humans, certain forms of APOE increase the risk of Alzheimer’s disease, but one form of APOE associated with risk is less effective at moving lipids from neurons to glia. Although this does not prove a direct link from sleep deprivation to Alzheimer’s disease, it does suggest a link worth taking seriously.

“In very basic research on sleep, we are discovering processes that are regulated by sleep, associated with Alzheimer’s disease, and inhibited in Alzheimer’s disease,” Sehgal said. “Sleep disturbances in Alzheimer’s disease may be due to impairments in these two processes.”

Sleep keeps the brain active

The broader hope here is that by understanding what sleep does at the cellular level – how it manages damage, energy, recycling and transport – researchers may gain clearer insight into why sleep disorders appear so frequently. brain decline.

Sleep science didn’t “wake up” because it became a fad. It was a wake-up call because biology is too basic to ignore.

The more researchers study it, the more sleep feels like maintenance mode for the brain rather than downtime.

The research will be published in a journal nature.

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