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 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!

Denver news in your inbox

Catch up on 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!

Des Moines news in your inbox

Catch up on 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!

Minneapolis-St. Paul news in your inbox

Catch up on 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!

Tampa Bay news in your inbox

Catch up on 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!

Charlotte news in your inbox

Catch up on 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!

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!

Neural activity in a zebrafish transitioning from waking to sleeping. Credit: Leung et. al. Nature 2019.

Most animals sleep, but scientists still lack a complete understanding of why, the biological factors that regulate sleep cycles and how the behavior evolved.

Driving the news: A new study in Nature on tiny zebrafish finds how humans sleep today may have first evolved in vertebrates more than 430 million years ago.

Why it matters: Scientists hope a better understanding of how zebrafish sleep, down to the cellular level, could unlock avenues for new treatments of sleep disorders that affect 50-70 million Americans but are often undiagnosed. It could also improve their understanding of sleep's role in memory and our physical health.

What they did: Zebrafish lack a neocortex — the part of the mammalian brain involved in higher order functions such as sleep and the target of sleep studies — so the scientists from Stanford University and institutions in Japan and France needed to find a workaround.

  • They developed an imaging platform that allowed them to view proxies for brain and muscle activity via fluorescence, as well as heart rate and eye movement.
  • They used two-week-old zebrafish since they are transparent, and therefore ideal for fluorescent imaging techniques.
  • They also performed other experiments to determine the effects of particular compounds on zebrafish sleep and wake cycles.

What they found: Ependymal cells — present in humans and zebrafish, and known to play a role in the brain and spinal cord — are among the first to be activated as the fish fall asleep.

  • The researchers also found human hypnotics — compounds found in sleeping pills and anesthetics — can also induce sleep phases in the fish that are analogous to humans.
  • And similar to what is seen in humans, chemicals released by neurons in the zebrafish brain regulate the creature's muscles and sleep.

What's new: Scientists had observed invertebrates (octopi, insects) and vertebrates (fishes, amphibians, birds, mammals) sleeping but the physiological signatures of sleep, like rapid eye movements, had only been observed in mammals, birds and reptiles, study co-author Philippe Mourrain of Stanford University tells Axios.

What they're saying: “You can’t just say sleep is sleep,” Jerry Siegel, a sleep scientist at UCLA who was not involved in the study, told National Geographic. He cautioned that connections between sleep in young zebrafish and sleep in humans are less straightforward than the study suggests. For example, he said, many mammals lack REM sleep completely, and some mammals sleep 20 hours a day whereas others just need 6 to 8 hours or less.

The study's lead author, Louis C. Leung of Stanford, tells Axios:

"I encourage everyone to cherish what has taken 100's of millions of years to create and hope there is soon a change in the public narrative regarding the importance of sleep — we should be proud not embarrassed to get enough sleep."

What's next: Developing animal models that examine sleep functions at the cellular level, like the one in this study, could lead to treatments for sleep disturbances that are linked to psychiatric disorders as well as Parkinson's and Alzheimer's.

Go deeper: Americans are sleeping more

Go deeper

Fringe right plots new attacks out of sight

Illustration: Aïda Amer/Axios

Domestic extremists are using obscure and private corners of the internet to plot new attacks ahead of Inauguration Day. Their plans are also hidden in plain sight, buried in podcasts and online video platforms.

Why it matters: Because law enforcement was caught flat-footed during last week's Capitol siege, researchers and intelligence agencies are paying more attention to online threats that could turn into real-world violence.

Kids’ screen time up 50% during pandemic

Illustration: Sarah Grillo/Axios

When the coronavirus lockdowns started in March, kidstech firm SuperAwesome found that screen time was up 50%. Nearly a year later, that percentage hasn't budged, according to new figures from the firm.

Why it matters: For most parents, pre-pandemic expectations around screen time are no longer realistic. The concern now has shifted from the number of hours in front of screens to the quality of screen time.

In photos: D.C. and U.S. states on alert for pre-inauguration violence

National Guard troops stand behind security fencing with the dome of the U.S. Capitol Building behind them, on Jan. 16. Photo: Kent Nishimura / Los Angeles Times via Getty Images

Security has been stepped up in Washington, D.C., and state capitols across the U.S. as authorities brace for potential violence this weekend.

Driving the news: Following the Jan. 6 insurrection at the U.S. Capitol by some supporters of President Trump, the FBI has said there could be armed protests in D.C. and in all 50 state capitols in the run-up to President-elect Joe Biden's inauguration Wednesday.

You’ve caught up. Now what?

Sign up for Mike Allen’s daily Axios AM and PM newsletters to get smarter, faster on the news that matters.

Please enter a valid email.

Please enter a valid email.

Subscription failed
Thank you for subscribing!