Among some killer whale moms, lifelong feeding for adult sons but not daughters could be a long-term investment play. The delayed payoff? Greater grandmotherly glory.

Females in a quirky population of killer whales off the Pacific Coast of North America let their grown mama’s boys share fish that mom catches. Biologists have known that this pampering continues throughout a son’s life, which can last decades. Grown daughters, often feeding their own offspring, however, don’t get such a bonus.
Scrutinizing decades of data has now revealed what moms sacrifice to lavish a lifetime of food on a son, researchers report February 8 in Current Biology. A mother’s yearly chance of successfully weaning a calf drops by about half after she has a son, says behavioral ecologist Michael Weiss of the Center for Whale Research in Friday Harbor, Wash.

For the moms, “it’s a huge, huge cost that they’re taking on,” Weiss says. It “emphasizes kind of the uniqueness and the intensity of this mother-son bond in killer whales.” For creatures that bear their young in a series, he says, this finding is “our first kind of direct evidence of any animal showing lifetime parental investment.”

These killer whales off the coast of Washington State and British Columbia, in “the southern resident” population of Orcinus orca, don’t migrate. Instead they specialize in feeding year-round on the region’s fish, such as big chinook salmon.

When moms catch a fish, “they do this huge head jerk, and one half of the fish stays in the mouth and the other half kind of trails behind them as they swim on,” Weiss says. A son swimming with her can then grab that other half. “It’s not the son coming up and grabbing the fish out of her mouth,” he says.

The son’s company looks consensual to Weiss. Mothers and sons “spend a lot of time kind of floating at the surface together … just kind of enjoying each other’s company.” Whale watchers need to take care reading interpretations into behavior, he says, but his “intuition from watching them is more about the mom wanting to provide for the son.”

Weiss doesn’t think the decline in new births after producing a son comes from any lack of opportunity to mate. “These whales are really social,” he says. “They’re usually in quite large groups, and usually with at least one sexually mature male around.” When watching them from drones, “we see that social behavior in these whales often involves a lot of sexual behavior,” he says. Nevertheless, all those halved fishes may not give a mom enough nutrition for the demands of whale pregnancy.

Mom’s grandchild tally however can make up for her own limited reproduction as she coddles her sons, the whale records show. Sons don’t have to parent. They just deliver sperm to the right address. Plus, the longer males live, the better, Weiss says. For a few years, genetics suggested that the two oldest males in the southern resident population were siring more than half the new calves.
Female killer whales, however, face more constraints. Killer whale pregnancies last some 18 months. So a Casanova whale’s sister gets preoccupied for a long time producing just one wrinkly not-so-little darling and then nurturing it to independence.

Female killer whales do have a chance to help later generations survive, because the species is among the few nonhuman mammals that experience menopause (SN: 3/5/15; SN: 8/19/13). (Females can stop reproducing in their 30s or 40s, but can live into their 80s).

Whether moms in other killer whale populations also routinely and consequentially serve dinner for grown sons isn’t an easy question to answer. Weiss wonders whether the same male whales in another place, perhaps with more abundant fish, would still reduce their mothers’ success at later births.

No other killer whale population’s records can match the depth of the ones Weiss used, says cetacean biologist Eve Jourdain of the University of Oslo. Her research focuses on killer whales around Norway that follow the seasonal movements of herring and other food bonanzas.

Jourdain doesn’t recall moms flinging fish, but she watches the whales herding local herring into big fish balls of swimming dinner. Which they share. So there may be other kinds of food-based bonding yet to be analyzed.

If you’re a museum aficionado itching for a new place to explore, 2023 has you covered. New science museums and exhibitions are opening, and some zoos are expanding. This sampling of destinations to check out in the new year or beyond has something for everyone, whether you’re a wildlife lover, space nerd or history buff.

Grand Egyptian Museum
Outside Cairo
Opens: To be announced

2022 marked the 100th anniversary of the discovery of King Tut’s tomb (SN: 11/19/22, p. 14). Now, thousands of artifacts from the tomb — along with tens of thousands of other archaeological finds from ancient Egypt — will go on display when this museum, located within view of the Pyramids of Giza, opens. More than a decade in the making, it will be one of the largest archaeological museums in the world.
Richard Gilder Center for Science, Education and Innovation
American Museum of Natural History
New York City
Opens: February 17

This multistory building will add tons of new exhibit space to the more than 150-year-old museum. Visitors can explore an insectarium that includes one of the world’s largest displays of live leaf-cutting ants and come face-to-face with dozens of butterfly species in a vivarium. Meanwhile, the interconnectedness of life will be on display in the immersive, 360-degree “Invisible Worlds” exhibition.
Galápagos Islands
Houston Zoo
Opens: April 2023

If you can’t travel to the Galápagos Islands, a trip to Texas might be the next best thing. Giant tortoises, iguanas, penguins, sea lions, sharks and other creatures will inhabit this new exhibition that will re-create the land and marine ecosystems of the archipelago made famous by Charles Darwin.

Kansas City Zoo Aquarium
Opens: September 2023

The 34 exhibits of this new aquarium will allow visitors to glimpse a wide variety of ocean locales without having to leave the Midwest. Underwater residents will include sea urchins and sea anemones in a warm intertidal zone, fish swimming in a coral reef, comb jellies floating in the open ocean and sea otters playing along a rocky shore.
SPACE
Franklin Institute
Philadelphia
Opens: Fall 2023

To design this new two-story gallery dedicated to the future of space exploration, exhibit planners met with local students and teachers to find out what they wanted to learn. The result is an experience that, among other things, will showcase the current and future technologies needed to live and work in space as well as the many career paths into the aerospace industry.
Bird House
Smithsonian’s National Zoo
Washington, D.C.
Opens: To be announced

With a focus on bird migration and conservation in the Americas, the zoo’s new bird house will feature three aviaries: The first will show how the Delaware Bay is a key refueling spot for migratory shorebirds, the second will demonstrate how seasonal wetlands in the Midwest serve waterfowl and the third will illustrate how a tropical coffee farm can provide respite for songbirds in winter.
Robot & AI Museum
Seoul, South Korea
Opens: To be announced

Though details are still scant, this museum dedicated to furthering public knowledge of robotics, artificial intelligence and machine learning is expected to open later this year.

High-tech shrink art may be the key to making tiny electronics, 3-D nanostructures or even holograms for hiding secret messages.

A new approach to making tiny structures relies on shrinking them down after building them, rather than making them small to begin with, researchers report in the Dec. 23 Science.

The key is spongelike hydrogel materials that expand or contract in response to surrounding chemicals (SN: 1/20/10). By inscribing patterns in hydrogels with a laser and then shrinking the gels down to about one-thirteenth their original size, the researchers created patterns with details as small as 25 billionths of a meter across.
At that level of precision, the researchers could create letters small enough to easily write this entire article along the circumference of a typical human hair.

Biological scientist Yongxin Zhao and colleagues deposited a variety of materials in the patterns to create nanoscopic images of Chinese zodiac animals. By shrinking the hydrogels after laser etching, several of the images ended up roughly the size of a red blood cell. They included a monkey made of silver, a gold-silver alloy pig, a titanium dioxide snake, an iron oxide dog and a rabbit made of luminescent nanoparticles.
Because the hydrogels can be repeatedly shrunk and expanded with chemical baths, the researchers were also able to create holograms in layers inside a chunk of hydrogel to encode secret information. Shrinking a hydrogel hologram makes it unreadable. “If you want to read it, you have to expand the sample,” says Zhao, of Carnegie Mellon University in Pittsburgh. “But you need to expand it to exactly the same extent” as the original. In effect, knowing how much to expand the hydrogel serves as a key to unlock the information hidden inside.

But the most exciting aspect of the research, Zhao says, is the wide range of materials that researchers can use on such minute scales. “We will be able to combine different types of materials together and make truly functional nanodevices.”

A 120-million-year-old fossil bird found in China could offer some new clues about how landbound dinosaurs evolved into today’s flying birds. The dove-sized Cratonavis zhui sported a dinosaur-like head atop a body similar to those of today’s birds, researchers report in the January Nature Ecology & Evolution.

The flattened specimen came from the Jiufotang Formation, an ancient body of rock in northeastern China that is a hotbed for preserved feathered dinosaurs and archaic birds. CT scans revealed that Cratonavis had a skull that was nearly identical (albeit smaller) as those of theropod dinosaurs like Tyrannosaurus rex, paleontologist Li Zhiheng of the Chinese Academy of Sciences in Beijing and colleagues report. This means that Cratonavis still hadn’t evolved the mobile upper jaw found in modern birds (SN: 5/2/18).
It’s among just a handful of specimens that belong to a recently identified group of intermediate birds known as the jinguofortisids, says Luis Chiappe, a paleontologist at the Natural History Museum of Los Angeles County who was not involved in the study. Its dino-bird mishmash “is not unexpected.” Most birds discovered from the Age of Dinosaurs exhibited more primitive, toothed heads than today’s birds, he says. But the new find “builds on our understanding of this primitive group of birds that are at the base of the tree of birds.”

Cratonavis also had an unusually elongated scapula and hallux, or backward-facing toe. Rarely seen in Cretaceous birds, enlarged shoulder blades might have compensated for the bird’s otherwise underwhelming flight mechanics, the researchers say. And that hefty big toe? It bucks the trend of shrinking metatarsals seen as birds continued to evolve. Cratonavis might have used this impressive digit to hunt like today’s birds of prey, Li’s team says.

Filling those shoes may have been too big of a job for Cratonavis, though. Given its size, Chiappe says, the dino-headed bird would have most likely been a petite hunter, taking down the likes of beetles, grasshoppers and the occasional lizard rather than terrorizing the skies.

Supercooled water is two of a kind, a new study shows.

Scientists have long suspected that water at subfreezing temperatures comes in two distinct varieties: a high-density liquid that appears at very high pressures and a low-density liquid at lower pressures. Now, ultrafast measurements have caught water morphing from one type of liquid to the other, confirming that hunch. The discovery, reported in the Nov. 20 Science, could help explain some of water’s quirks.

The experiment “adds more and more evidence to the idea that water really is two components … and that that is the reason that underlies why water is so weird,” says physicist Greg Kimmel of Pacific Northwest National Laboratory in Richland, Wash., who was not involved in the study.

When free from impurities, water can remain liquid below its typical freezing point of zero degrees Celsius, forming what’s called a supercooled liquid. But the dual nature of supercooled water was expected to appear in a temperature realm so difficult to study that it’s been dubbed “no-man’s-land.” Below around –40° C, water remains liquid for mere instants before it crystallizes into ice. Making the task even more daunting, the high-density phase appears only at very high pressures. Still, “people have dreamt about how to do an experiment,” says Anders Nilsson of Stockholm University.
Thanks to speedy experimental maneuvers, Nilsson and colleagues have infiltrated that no-man’s-land by monitoring water’s properties on a scale of nanoseconds. “This is one of the major accomplishments of this paper,” says computational chemist Gül Zerze of Princeton University. “I’m impressed with their work.”

The scientists started by creating a type of high-density ice. Then, a pulse from an infrared laser heated the ice, forming liquid water under high pressure. That water then expanded, and the pressure rapidly dropped. Meanwhile, the researchers used an X-ray laser to investigate how the structure of the water changed, based on how the X-rays scattered. As the pressure decreased, the water transitioned from a high-density to low-density fluid before crystallizing into ice.

Previous studies have used ultrafast techniques to find hints of water’s two-faced demeanor, but those have been done mainly at atmospheric pressure (SN: 9/28/20). In the new work, the water was observed at about 3,000 times atmospheric pressure and –68° C. “It’s the first time we have real experimental data at these pressures and temperatures,” says physicist Loni Kringle of Pacific Northwest National Laboratory, who was not involved with the experiment.

The result could indicate that supercooled water has a “critical point” — a certain pressure and temperature at which two distinct phases merge into one. In the future, Nilsson hopes to pinpoint that spot.

Such a critical point could explain why water is an oddball liquid. For most liquids, cooling makes them become denser and more difficult to compress. Water gets denser as it is cooled to 4° C, but becomes less dense as it is cooled further. Likewise, its compressibility increases as it’s cooled.

If supercooled water has a critical point, that could indicate that the water experienced in daily life is strange because, under typical pressures and temperatures, it is a supercritical liquid — a weird state that occurs beyond a critical point. Such a liquid would not be the high-density or low-density form, but would consist of some regions with a high-density arrangement of water molecules and other pockets of low density. The relative amounts of those two structures, which result from different arrangements of hydrogen bonds between the molecules, would change as the temperature changes, explaining why water behaves strangely as it is cooled.

So despite the fact that the experiment involved extreme pressures and temperatures, Nilsson says, “it influences water in our ordinary life.”

2022 was the year many people decided the coronavirus pandemic had ended.

President Joe Biden said as much in an interview with 60 Minutes in September. “The pandemic is over,” he said while strolling around the Detroit Auto Show. “We still have a problem with COVID. We’re still doing a lot of work on it. But the pandemic is over.”

His evidence? “No one’s wearing masks. Everybody seems to be in pretty good shape.”

But the week Biden’s remarks aired, about 360 people were still dying each day from COVID-19 in the United States. Globally, about 10,000 deaths were recorded every week. That’s “10,000 too many, when most of these deaths could be prevented,” the World Health Organization Director-General Tedros Adhanom Ghebreyesus said in a news briefing at the time. Then, of course, there are the millions who are still dealing with lingering symptoms long after an infection.
Those staggering numbers have stopped alarming people, maybe because those stats came on the heels of two years of mind-boggling death counts (SN Online: 5/18/22). Indifference to the mounting death toll may reflect pandemic fatigue that settled deep within the public psyche, leaving many feeling over and done with safety precautions.

“We didn’t warn people about fatigue,” says Theresa Chapple-McGruder, an epidemiologist in the Chicago area. “We didn’t warn people about the fact that pandemics can last long and that we still need people to be willing to care about yourselves, your neighbors, your community.”

Public health agencies around the world, including in Singapore and the United Kingdom, reinforced the idea that we could “return to normal” by learning to “live with COVID.” The U.S. Centers for Disease Control and Prevention’s guidelines raised the threshold for case counts that would trigger masking (SN Online: 3/3/22). The agency also shortened suggested isolation times for infected people to five days, even though most people still test positive for the virus and are potentially infectious to others for several days longer (SN Online: 8/19/22).

The shifting guidelines bred confusion and put the onus for deciding when to mask, test and stay home on individuals. In essence, the strategy shifted from public health — protecting your community — to individual health — protecting yourself.
Doing your part can be exhausting, says Eric Kennedy, a sociologist specializing in disaster management at York University in Toronto. “Public health is saying, ‘Hey, you have to make the right choices every single moment of your life.’ Of course, people are going to get tired with that.”

Doing the right thing — from getting vaccinated to wearing masks indoors — didn’t always feel like it paid off on a personal level. As good as the vaccines are at keeping people from becoming severely ill or dying of COVID-19, they were not as effective at protecting against infection. This year, many people who tried hard to make safe choices and had avoided COVID-19 got infected by wily omicron variants (SN Online: 4/22/22). People sometimes got reinfected — some more than once (SN: 7/16/22 & 7/30/22, p. 8).
Those infections may have contributed to a sense of futility. “Like, ‘I did my best. And even with all of that work, I still got it. So why should I try?’ ” says Kennedy, head of a Canadian project monitoring the sociological effects of the COVID-19 pandemic.

Getting vaccinated, masking and getting drugs or antibody treatments can reduce the severity of infection and may cut the chances of infecting others. “We should have been talking about this as a community health issue and not a personal health issue,” Chapple-McGruder says. “We also don’t talk about the fact that our uptake [of these tools] is nowhere near what we need” to avoid the hundreds of daily deaths.

A lack of data about how widely the coronavirus is still circulating makes it difficult to say whether the pandemic is ending. In the United States, the influx of home tests was “a blessing and a curse,” says Beth Blauer, data lead for the Johns Hopkins University Coronavirus Resource Center. The tests gave an instant readout that told people whether they were infected and should isolate. But because those results were rarely reported to public health officials, true numbers of cases became difficult to gauge, creating a big data gap (SN Online: 5/27/22).
The flow of COVID-19 data from many state and local agencies also slowed to a trickle. In October, even the CDC began reporting cases and deaths weekly instead of daily. Altogether, undercounting of the coronavirus’s reach became worse than ever.

“We’re being told, ‘it’s up to you now to decide what to do,’ ” Blauer says, “but the data is not in place to be able to inform real-time decision making.”

With COVID-19 fatigue so widespread, businesses, governments and other institutions have to find ways to step up and do their part, Kennedy says. For instance, requiring better ventilation and filtration in public buildings could clean up indoor air and reduce the chance of spreading many respiratory infections, along with COVID-19. That’s a behind-the-scenes intervention that individuals don’t have to waste mental energy worrying about, he says.

The bottom line: People may have stopped worrying about COVID-19, but the virus isn’t done with us yet. “We have spent two-and-a-half years in a long, dark tunnel, and we are just beginning to glimpse the light at the end of that tunnel. But it is still a long way off,” WHO’s Tedros said. “The tunnel is still dark, with many obstacles that could trip us up if we don’t take care.” If the virus makes a resurgence, will we see it coming and will we have the energy to combat it again?

A group at the National Bureau of Standards at B­oulder, Colo., now reports an extremely accurate [speed of light] measurement using the wavelength and frequency of a helium-neon laser.… The result gives the speed of light as 299,792.4562 kilometers per second.

Update
That 1972 experiment measured the two-way speed of light, or the average speed of photons that traveled from their source to a reflective surface and back. The result, which still holds up, helped scientists redefine the standard length of the meter (SN: 10/22/83, p. 263). But they weren’t done putting light through its paces. In the late 1990s and early 2000s, photons set a record for slowest measured speed of light at 17 meters per second and froze in their tracks for one-thousandth of a second (SN: 1/27/01, p. 52). For all that success, one major hurdle remains: directly testing the one-way speed of light. The measurement, which many scientists say is impossible to make, could resolve the long-standing question of whether the speed of light is uniform in all directions.

Some immune defenses of the brain may have their roots in the gut.

A new study in mice finds that immune cells are first trained in the gut to recognize and launch attacks on pathogens, and then migrate to the brain’s surface to protect it, researchers report online November 4 in Nature. These cells were also found in surgically removed parts of human brains.

Every minute, around 750 milliliters of blood flow through the brain, giving bacteria, viruses or other blood-borne pathogens an opportunity to infect the organ. For the most part, the invaders are kept out by three membrane layers, called the meninges, which wrap around the brain and spinal cord and act as a physical barrier. If a pathogen does manage to breach that barrier, the researchers say, the immune cells trained in the gut are ready to attack by producing a battalion of antibodies.

The most common route for a pathogen to end up in the bloodstream is from the gut. “So, it makes perfect sense for these [immune cells] to be educated, trained and selected to recognize things that are present in the gut,” says Menna Clatworthy, an immunologist at the University of Cambridge.

Clatworthy’s team found antibody-producing plasma cells in the leathery meninges, which lie between the brain and skull, in both mice and humans. These immune cells produced a class of antibodies called immunoglobulin A, or IgA.

These cells and antibodies are mainly found in the inner lining of the gut and lungs, so the scientists wondered if the cells on the brain had any link to the gut. It turned out that there was: Germ-free mice, which had no microbes in their guts, didn’t have any plasma cells in their meninges either. However, when bacteria from the poop of other mice and humans were transplanted into the mice’s intestines, their gut microbiomes were restored, and the plasma cells then appeared in the meninges.

“This was a powerful demonstration of how important the gut could be at determining what is found in the meninges,” Clatworthy says.

Researchers captured microscope images of an attack in the meninges of mice that was led by plasma cells that had likely been trained in the guts. When the team implanted a pathogenic fungus, commonly found in the intestine, into the mice’s bloodstream, the fungus attempted to enter the brain through the walls of blood vessels in the meninges. However, plasma cells in the membranes formed a mesh made of IgA antibodies around the pathogen, blocking its entry. The plasma cells are found along the blood vessels, Clatworthy says, where they can quickly launch an attack on pathogens.

“To my knowledge, this is the first time anyone has shown the presence of plasma cells in the meninges. The study has rewritten the paradigm of what we know about these plasma cells and how they play a critical role in keeping our brain healthy,” says Matthew Hepworth, an immunologist at the University of Manchester in England who was not involved with the study. More research is needed to classify how many of the plasma cells in the meninges come from the gut, he says.

The finding adds to growing evidence that gut microbes can play a role in brain diseases. A previous study, for instance, suggested that in mice, boosting a specific gut bacterium could help fight amyotrophic lateral sclerosis, or ALS, a fatal neurological disease that results in paralysis (SN: 7/22/19). And while the new study found the plasma cells in the brains of healthy mice, previous research has found other gut-trained cells in the brains of mice with multiple sclerosis, an autoimmune disease of the brain and the spinal cord.

For now, the researchers want to understand what cues plasma cells follow in the guts to know it is time for them to embark on a journey to the brain.

When some bacteria manage to escape being killed by a virus, the microbes end up hamstringing themselves. And that could be useful in the fight to treat infections.

The bacterium Shigella flexneri — one cause of the infectious disease shigellosis — can spread within cells that line the gut by propelling itself through the cells’ barriers. That causes tissue damage that can lead to symptoms like bloody diarrhea. But when S. flexneri in lab dishes evolved to elude a type of bacteria-killing virus, the bacteria couldn’t spread cell to cell anymore, making it less virulent, researchers report November 17 in Applied and Environmental Microbiology.

The research is a hopeful sign for what’s known as phage therapy (SN: 11/20/02). With antibiotic-resistant microbes on the rise, some researchers see viruses that infect and kill only bacteria, known as bacteriophages or just phages, as a potential option to treat antibiotic-resistant infections (SN: 11/13/19). With phage therapy, infected people are given doses of a particular phage, which kill off the problematic bacteria. The problem, though, is that over time those bacteria can evolve to be resistant against the phage, too.

“We’re kind of expecting phage therapy to fail, in a sense,” says Paul Turner, an evolutionary biologist and virologist at Yale University. “Bacteria are very good at evolving resistance to phages.”
But that doesn’t mean the bacteria emerge unscathed. Some phages attack and enter bacteria by latching onto bacterial proteins crucial for a microbe’s function. If phage therapy treatments relied on such a virus, that could push the bacteria to evolve in such a way that not only helps them escape the virus but also impairs their abilities and makes them less deadly. People infected with these altered bacteria might have less severe symptoms or may not show symptoms at all.

Previous studies with the bacteria Pseudomonas aeruginosa, for instance, have found that phage and bacteria can engage in evolutionary battles that drive the bacteria to be more sensitive to antibiotics. The new study hints that researchers could leverage the arms race between S. flexneri and the newly identified phage, which was dubbed A1-1 after being found in Mexican wastewater, to treat shigellosis.

S. flexneri in contaminated water is a huge problem in parts of the world where clean water isn’t always available, such as sub-Saharan Africa and southern Asia, says Kaitlyn Kortright, a microbiologist also at Yale University. Every year, approximately 1.3 million people die from shigellosis, which is caused by four Shigella species. More than half of those deaths are in children younger than 5 years old. What’s more, antibiotics to treat shigellosis can be expensive and hard to access in those places. And S. flexneri is becoming resistant to many antibiotics. Phage therapy could be a cheaper, more accessible option to treat the infection.

The blow to S. flexneri’s cellular spread comes because to enter cells, A1-1 targets a protein called OmpA, which is crucial for the bacteria to rupture host cell membranes. The researchers found two types of mutations that made S. flexneri resistant to A1-1. Some bacteria had mutations in the gene that produces OmpA, damaging the protein’s ability to help the microbes spread from cell to cell. Others had changes to a structural component of bacterial cells called lipopolysaccharide.

The mutations in lipopolysaccharide were surprising, Kortright says, because the relationship between that structural component and OmpA isn’t fully worked out. One possibility is that those mutations distort OmpA’s structure in a way that the phage no longer recognizes it and can’t enter bacterial cells.

One lingering question is whether S. flexneri evolves in the same way outside a lab dish, says Saima Aslam, an infectious diseases physician at the University of California, San Diego who was not involved in the work. Still, the findings show that it’s “not always a bad thing” when bacteria become phage-resistant, she says.

The twilight time between fully awake and sound asleep may be packed with creative potential.

People who recently drifted off into a light sleep later had problem-solving power, scientists report December 8 in Science Advances. The results help demystify the fleeting early moments of sleep and may even point out ways to boost creativity.

Prolific inventor and catnapper Thomas Edison was rumored to chase those twilight moments. He was said to fall asleep in a chair holding two steel ball bearings over metal pans. As he drifted off, the balls would fall. The ensuing clatter would wake him, and he could rescue his inventive ideas before they were lost to the depths of sleep.

Delphine Oudiette, a cognitive neuroscientist at the Paris Brain Institute, and colleagues took inspiration from Edison’s method of cultivating creativity. She and her colleagues brought 103 healthy people to their lab to solve a tricky number problem. The volunteers were asked to convert a string of numbers into a shorter sequence, following two simple rules. What the volunteers weren’t told was that there was an easy trick: The second number in the sequence would always be the correct final number, too. Once discovered, this cheat code dramatically cut the solving time.
After doing 60 of these trials on a computer, the volunteers earned a 20-minute break in a quiet, dark room. Reclined and holding an equivalent of Edison’s “alarm clock” (a light drinking bottle in one dangling hand), participants were asked to close their eyes and rest or sleep if they desired. All the while, electrodes monitored their brain waves.

About half of the participants stayed awake. Twenty-four fell asleep and stayed in the shallow, fleeting stage of sleep called N1. Fourteen people progressed to a deeper stage of sleep called N2.

After their rest, participants returned to their number problem. The researchers saw a stark difference between the groups: People who had fallen into a shallow, early sleep were 2.7 times as likely to spot the hidden trick as people who didn’t fall asleep, and 5.8 times as likely to spot it as people who had reached the deeper N2 stage.

Such drastic differences in these types of experiments are rare, Oudiette says. “We were quite astonished by the extent of the results.” The researchers also identified a “creative cocktail of brain waves,” as Oudiette puts it, that seemed to accompany this twilight stage — a mixture of alpha brain waves that usually mark relaxation mingled with the delta waves of deeper sleep.

The study doesn’t show that the time spent in N1 actually triggered the later realization, cautions John Kounios, a cognitive neuroscientist at Drexel University in Philadelphia who cowrote the 2015 book The Eureka Factor: Aha Moments, Creative Insight, and the Brain. “It could have been possible that grappling with the problem and initiating an incubation process caused both N1 and the subsequent insight,” he says, making N1 a “by-product of the processes that caused insight rather than the cause.”

More work is needed to untangle the connection between N1 and creativity, Oudiette says. But the results raise a tantalizing possibility, one that harkens to Edison’s self-optimizations: People might be able to learn to reach that twilight stage of sleep, or to produce the cocktail of brain waves associated with creativity on demand.

It seems Edison was onto something about the creative powers of nodding off. But don’t put too much stock in his habits. He is also said to have considered sleep “a criminal waste of time.”