Sleep is critical for all sorts of reasons, but a team of international scientists has discovered a new incentive for getting eight hours of sleep every night: it helps the brain to store and learn a new language.

A study led by the University of South Australia (UniSA) and published in the Journal of Neuroscience has revealed that the coordination of two electrical events in the sleeping brain significantly improves our ability to remember new words and complex grammatical rules.

In an experiment with 35 native English-speaking adults, researchers tracked the brain activity of participants learning a miniature language called Mini Pinyin that is based on Mandarin but with similar grammatical rules to English.

Half of the participants learned Mini Pinyin in the morning and then returned in the evening to have their memory tested. The other half learned Mini Pinyin in the evening and then slept in the laboratory overnight while their brain activity was recorded. Researchers tested their progress in the morning.

Those who slept performed significantly better compared to those who remained awake.

Lead researcher  Dr Zachariah Cross, who did his PhD at UniSA but is now based at Northwestern University in Chicago, says sleep-based improvements were linked to the coupling of slow oscillations and sleep spindles – brainwave patterns that synchronise during NREM sleep.

“This coupling likely reflects the transfer of learned information from the hippocampus to the cortex, enhancing long-term memory storage,” Dr Cross says.

“Post-sleep neural activity showed unique patterns of theta oscillations associated with cognitive control and memory consolidation, suggesting a strong link between sleep-induced brainwave co-ordination and learning outcomes.”

UniSA researcher Dr Scott Coussens says the study underscores the importance of sleep in learning complex linguistic rules.

“By demonstrating how specific neural processes during sleep support memory consolidation, we provide a new perspective on how sleep disruption impacts language learning,” Dr Coussens says. “Sleep is not just restful; it’s an active, transformative state for the brain.”

The findings could also potentially inform treatments for individuals with language-related impairments, including autism spectrum disorder (ASD) and aphasia, who experience greater sleep disturbances than other adults.

Research on both animals and humans shows that slow oscillations improve neural plasticity – the brain’s ability to change and adapt in response to experiences and injury.

“From this perspective, slow oscillations could be increased via methods such as transcranial magnetic stimulation to accelerate aphasia-based speech and language therapy,” Dr Cross says.

In future, the researchers plan to explore how sleep and wake dynamics influence the learning of other complex cognitive tasks.

“Understanding how the brain works during sleep has implications beyond language learning. It could revolutionize how we approach education, rehabilitation, and cognitive training.”

The World Health Organization recommends no more than two to three hours per day of sedentary time for youth. However, adolescents worldwide are spending an average of 8 to 10 hours per day engaging in sedentary activities such as watching television, using electronic devices, playing video games and riding in motorized vehicles, according to a multinational study published in the Nov. 29, 2024 issue of the International Journal of Behavioral Nutrition and Physical Activity.

The most notable finding of the study, led by principal investigator James F. Sallis, Ph.D., distinguished professor at the Herbert Wertheim School of Public Health and Human Longevity Science at University of California San Diego, and colleagues from 14 countries, found that simply having a personal social media account was linked with higher total sedentary time in both males and females. Social media was also related to more self-reported screen time.

“Although there is great concern about negative effects of social media on youth mental health, this study documents a pathway for social media to harm physical health as well,” said Sallis, who is also a professorial fellow at the Australian Catholic University.

“These findings are concerning, as excessive sedentary behavior has been linked to a range of health problems, including obesity, diabetes and mental health issues.”

Researchers analyzed accelerometer data from 3,982 adolescents aged 11 to 19 and survey measures of sedentary behavior from 6,302 participants in the International Physical Activity and the Environment Network (IPEN) Adolescent Study, which covered 15 geographically and culturally diverse countries across six continents.

The number of electronic devices within a home, how many adolescents had their own social media accounts and neighborhood walkability were significantly different across countries.

For example, adolescents from India had an average of 1.2 electronic devices in the bedroom and 0.5 personal electronic devices, while the average number of such devices in Denmark was 4.2 and 2.3, respectively. In India and Bangladesh, fewer than 30% of adolescents reported having their own social media account, compared to higher socio-economic status countries where it was over 90%.

Parents reporting on walkability identified Australia as having high access to parks, while Nigerian parents reported no access, and parents in Bangladesh and India reported poor access. Traffic was a concern among parents in Brazil, Malaysia, Bangladesh, India, and Israel, and concerns about crime were high in the first three countries.

Adolescents who reported less recreational screen time lived in walkable neighborhoods and had better perceptions of safety from traffic and crime than others. Girls who lived in neighborhoods designed to support physical activity were less likely to be sedentary.

Despite differences in culture, built environments and extent of sedentary time, patterns of association were generally similar across countries, said the study’s lead author Ranjit Mohan Anjana, M.D., Ph.D., of Dr. Mohan’s Diabetes Specialties Centre and Madras Diabetes Research Foundation in India.

“Together, parents, policymakers and technology companies can work together to reduce access to screens, limit social media engagement and promote more physical activity, thus helping adolescents develop healthier habits and reduce their risk of chronic diseases,” said Anjana.

The study’s findings have significant implications for public health policy and highlight the need for further research into the causes and consequences of sedentary behavior among teenagers.

Countries involved in study: Australia, Bangladesh, Belgium, Brazil, China, Czechia, Denmark, India, Israel, Malaysia, Nigeria, Portugal, Spain and United States.

People who use both vapes and cigarettes are less likely to quit compared to people who only smoke or only vape, according to a study published in ERJ Open Research. Instead, the research suggests that over time, most of these ‘dual users’ tend to revert to only smoking cigarettes.

The researchers say their findings suggest that taking up vaping while continuing to smoke will probably not help people to stop smoking.

The study, by researchers from Germany, the USA and Denmark, was authored by Josef Hamoud from the University Medical Center Göttingen, Germany. It is a systematic review and meta-analysis, meaning researchers reviewed all existing research on people using both vapes and cigarettes and combined the data into one study.

Hamoud said: “Vaping has become widespread among adolescents and adults worldwide. Given the extensive marketing of vapes as healthier alternatives to conventional smoking, they have gained popularity among people trying to quit smoking. Some people are using them in addition to their conventional cigarettes, classifying them as dual users.

“There is still a lot we don’t know about the long-term health effects of vaping. However, credible studies have already delivered concerning results indicating that dual use might be even more harmful than conventional smoking.”

The review brings together 16 individual studies looking at whether groups of dual users went on to quit smoking, switch to vaping only, switch to smoking only or continue dual use over time. The analyses incorporate data on up to 9,337 people including 2,432 dual users.

When researchers compared dual users with people who only smoked cigarettes or only vaped, they found that dual users were less likely to quit completely. Over time, the analysis showed that the majority of dual users reverted to smoking conventional cigarettes.

The proportion of dual users who quit completely was 3% over a period of four to eight months, 5% by eight to 16 months, 13% by 16 to 24 months and 24% by 24 to 48 months. This compares to 6%, 7%, 17% and 25% respectively over the same time periods in people who only smoke and 8%, 19%, 26% and 35% respectively in people who only vape.

Over a period of four to eight months, 30% of dual users switched to cigarettes only. Between eight and 16 months, 47% of dual users switched to cigarettes only. Between 16 and 24 months, the proportion was 58% and after 24 to 48 months, the proportion was 55%.

Most dual users continued to use cigarettes across the time periods. Combining those who continued dual use with those who transitioned to smoking only, the total proportion using cigarettes ranged from 90% to 63%.

The researchers also point out that over the medium term (eight to 16 months), 38% of dual users were still using both vapes and cigarettes. “This cannot be considered a simple ‘transitional state’, but rather a risk for prolonged double exposure,” Hamoud said.

He continued: “Given these findings, we believe that dual use might prove to be a major hinderance in achieving smoking abstinence and this practice should not be recommended for treating nicotine addiction. In addition, while long term health effects of vapes need to be studied further, the double exposure to large amounts of nicotine and toxicants from both conventional cigarettes and vapes are a great concern for public health.”

The researchers say that because they were combining several studies, each with a slightly different approach, it was not possible to categorise different types of dual use, such as people who mostly smoke but occasionally vape.

Hamoud added: “While it may have been argued that heavy smokers might benefit from dual use by reducing their daily cigarette consumption, the high nicotine content of vapes adds to the risk of continued nicotine addiction. Future studies must further stratify dual-use groups to investigate the health implications over time.”

Dr Filippos Filippidis is Chair of the European Respiratory Society Tobacco Control Committee, a reader in public health at Imperial College London, UK, and was not involved in the research. He said: “We know that vaping is commonplace and that many people use e-cigarettes as well as cigarettes, often in the hopes of cutting down on smoking or quitting the habit. This large study examined all existing evidence on dual users, and it showed that, for most people, this is not a stepping stone to quitting”.

“Nicotine in vapes is highly addictive, so we need to do all we can to discourage non-smokers from starting to vape. E-cigarettes may have a role in smoking cessation for some people, but we need to make sure appropriate support is freely available to help people to quit, as it’s clear that many end up being dual users, which can actually undermine smoking cessation attempts.”