Sign up for our daily briefing

Make your busy days simpler with Axios AM/PM. Catch up on what's new and why it matters in just 5 minutes.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on the day's biggest business stories

Subscribe to Axios Closer for insights into the day’s business news and trends and why they matter

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Stay on top of the latest market trends

Subscribe to Axios Markets for the latest market trends and economic insights. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sports news worthy of your time

Binge on the stats and stories that drive the sports world with Axios Sports. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Tech news worthy of your time

Get our smart take on technology from the Valley and D.C. with Axios Login. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Get the inside stories

Get an insider's guide to the new White House with Axios Sneak Peek. Sign up for free.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Catch up on coronavirus stories and special reports, curated by Mike Allen everyday

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Denver news?

Get a daily digest of the most important stories affecting your hometown with Axios Denver

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Des Moines news?

Get a daily digest of the most important stories affecting your hometown with Axios Des Moines

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Twin Cities news?

Get a daily digest of the most important stories affecting your hometown with Axios Twin Cities

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Tampa Bay news?

Get a daily digest of the most important stories affecting your hometown with Axios Tampa Bay

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Charlotte news?

Get a daily digest of the most important stories affecting your hometown with Axios Charlotte

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Nashville news?

Get a daily digest of the most important stories affecting your hometown with the Axios Nashville newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Columbus news?

Get a daily digest of the most important stories affecting your hometown with the Axios Columbus newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Want a daily digest of the top Dallas news?

Get a daily digest of the most important stories affecting your hometown with the Axios Dallas newsletter.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Sign up for Axios NW Arkansas

Stay up-to-date on the most important and interesting stories affecting NW Arkansas, authored by local reporters

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Why do we sleep? Is it to allow a weary mind to recover from a long day of making tens of thousands of decisions? Maybe. But two scientific teams working on different aspects of the question have come up with a startling, new answer. We sleep in order to forget some of what we learned during the day, they wrote in a pair of studies in Science.

When we learn, neurons in our brain form links between each other. They're called synapses, and these connections between neurons form memories and allow us to access information. But they also can become a tangled bundle of connections that are quite messy – much like the way in which wires become a tangled mess behind our cable TV system.

When we sleep, these researchers discovered, our brain prunes these newly formed synapses and untangles them so that the important parts of what we learned during the day are stored and accessed more efficiently. Because our memories are stored in these neural networks, the work to clean them up while we sleep is important.

Researchers have known for some time that these connections between neurons can grow wildly during the day as our brains process massive amounts of information.

What they didn't know until these news studies were conducted, however, was what happened to this explosive growth of these synapses in brains. So they studied the brains of mice, and found that these connections shrank nearly 20% overnight. That's an extraordinary amount, and confirms that this is clearly a vital part of the brain's effort to streamline neural networks.

In the second study in Science, researchers literally created a tiny window that allowed them to peer into a mouse brain while it slept. They then placed chemicals on top of the synapses so that they could watch how it functioned overnight. They watched, through that tiny window, as a particular surface protein shrank the synapses.

That convinced the researchers that this streamlining of the neural networks allowed us to forget some portion of what we process each day so that we can store memories more efficiently and actually learn. "You can forget in a smart way," one of the researchers, Dr. Giulio Tononi, a biologist at the University of Wisconsin-Wisconsin, told Carl Zimmer of The New York Times.

Go deeper

Biden rejects Trump's latest executive privilege claims

Photo: Jim Watson and Saul Loeb/AFP via Getty Images

The White House on Monday rejected two more of former President Trump's claims of executive privilege over documents that the House select committee investigating the Jan. 6 Capitol riot requested, CNN first reported.

Why it matters: Trump's legal team is seeking to block some of the panel's requests for records by invoking executive privilege, which can allow presidents and their aides to sidestep congressional scrutiny. The Biden administration has maintained that it will evaluate on a case-by-case basis.

Amazon warehouse workers in New York file petition to hold unionization vote

Amazon workers and their supporters rally outside the National Labor Relations Board's regional office in Brooklyn, New York City, after filing a petition requesting an election to form a union. Photo: Gabby Jones/Bloomberg via Getty Images

Amazon warehouse workers in New York City filed a petition on Monday with the National Labor Relations Board (NLRB) to hold a vote on unionization.

Why it matters: The move comes six months after an organizing effort was defeated at Amazon's distribution center in Alabama.

Updated 2 hours ago - World

U.S. freezes aid to Sudan over military coup

Protesting the coup in Khartoum. Photo: AFP via Getty

The Biden administration froze a $700 million aid package to Sudan after a military coup on Monday threatened to end the country's transition toward democracy.

Driving the news: At least three protesters have been killed and dozens wounded in the chaotic scenes that followed the announcements from Gen. Abdel Fattah al-Burhan, the head of Sudan's ruling council, dissolving the government and declaring a state of emergency.