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But the study of adolescents in the US also showed that even those with better sleeping habits were not reaching the amount of sleep recommended for their age group. Sleep plays an important role in helping our bodies function. It is thought that while we are asleep, toxins that have built up in our brains are cleared out, and brain connections are consolidated and pruned, enhancing memory, learning, and problem-solving skills. Sleep has also been shown to boost our immune systems and improve our mental health. During adolescence, our sleep patterns change. We tend to start going to bed later and sleeping less, which affects our body clocks. All of this coincides with a period of important development in our brain function and cognitive development. The American Academy of Sleep Medicine says that the ideal amount of sleep during this period is between eight- and 10-hours’ sleep. Professor Barbara Sahakian from the Department of Psychiatry at the University of Cambridge said: “Regularly getting a good night’s sleep is important in helping us function properly, but while we know a lot about sleep in adulthood and later life, we know surprisingly little about sleep in adolescence, even though this is a crucial time in our development. How long do young people sleep for, for example, and what impact does this have on their brain function and cognitive performance?” Studies looking at how much sleep adolescents get usually rely on self-reporting, which can be inaccurate. To get around this, a team led by researchers at Fudan University, Shanghai, and the University of Cambridge turned to data from the Adolescent Brain Cognitive Development (ABCD) Study, the largest long-term study of brain development and child health in the United States. As part of the ABCD Study, more than 3,200 adolescents aged 11-12 years old had been given FitBits, allowing the researchers to look at objective data on their sleep patterns and to compare it against brain scans and results from cognitive tests. The team double-checked their results against two additional groups of 13-14 years old, totalling around 1,190 participants. The results are published today in Cell Reports. The team found that the adolescents could be divided broadly into one of three groups: Group One, accounting for around 39% of participants, slept an average (mean) of 7 hours 10 mins. They tended to go to bed and fall asleep the latest and wake up the earliest. Group Two, accounting for 24% of participants, slept an average of 7 hours 21 mins. They had average levels across all sleep characteristics. Group Three, accounting for 37% of participants, slept an average of 7 hours 25 mins. They tended to go to bed and fall asleep the earliest and had lower heart rates during sleep. Although the researchers found no significant differences in school achievement between the groups, when it came to cognitive tests looking at aspects such as vocabulary, reading, problem solving and focus, Group Three performed better than Group Two, which in turn performed better than Group One. Group Three also had the largest brain volume and best brain functions, with Group One the smallest volume and poorest brain functions. Professor Sahakian said: “Even though the differences in the amount of sleep that each group got was relatively small, at just over a quarter-of-an-hour between the best and worst sleepers, we could still see differences in brain structure and activity and in how well they did at tasks. This drives home to us just how important it is to have a good night’s sleep at this important time in life.” First author Dr Qing Ma from Fudan University said: “Although our study can’t answer conclusively whether young people have better brain function and perform better at tests because they sleep better, there are a number of studies that would support this idea. For example, research has shown the benefits of sleep on memory, especially on memory consolidation, which is important for learning.” The researchers also assessed the participants’ heart rates, finding that Group Three had the lowest heart rates across the sleep states and Group One the highest. Lower heart rates are usually a sign of better health, whereas higher rates often accompany poor sleep quality like restless sleep, frequent awakenings and excessive daytime sleepiness. Because the ABCD Study is a longitudinal study – that is, one that follows its participants over time – the team was able to show that the differences in sleep patterns, brain structure and function, and cognitive performance, tended be present two years before and two years after the snapshot that they looked at. Senior author Dr Wei Cheng from Fudan University added: “Given the importance of sleep, we now need to look at why some children go to bed later and sleep less than others. Is it because of playing videogames or smartphones, for example, or is it just that their body clocks do not tell them it’s time to sleep until later?” The research was supported by the National Key R&D Program of China, National Natural Science Foundation of China, National Postdoctoral Foundation of China and Shanghai Postdoctoral Excellence Program. The ABCD Study is supported by the National Institutes of Health. Reference Ma, Q et al. Neural correlates of device-based sleep characteristics in adolescents. Cell Reports; 22 Apr 2025; DOI: 10.1016/j.celrep.2025.115565 Adolescents who sleep for longer – and from an earlier bedtime – than their peers tend to have improved brain function and perform better at cognitive tests, researchers from the UK and China have shown. Even though the differences in the amount of sleep that each group got was relatively small, we could still see differences in brain structure and activity and in how well they did at tasksBarbara Sahakianharpazo_hope (Getty Images)Teenager asleep and wrapped in a blanket The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms. Yes

The UNESCO Memory of the World Programme serves as the documentary heritage equivalent of UNESCO World Heritage Sites, protecting invaluable records that tell the story of human civilisation. A collaboration between Cambridge University Library, the Natural History Museum, the Linnean Society of London, English Heritage’s Down House, the Royal Botanic Gardens, Kew and the National Library of Scotland, the Charles Darwin documentary heritage archive provides a unique window into the life and work of one of the world’s most influential natural scientists. The complete archive, comprising over 20,000 items across the six major institutions, includes Darwin’s records illustrating the development of his ground-breaking theory of evolution and extensive global travels. At Cambridge University Library, the Darwin Archive is a significant collection of Darwin’s books, experimental notes, correspondence, and photographs, representing his scientific and personal activities throughout his life. The collection in Cambridge includes Darwin’s pocket notebooks recording early statements of key ideas contributing to his theory of evolution, notably that species are not stable. These provide important insights into the development of his thought and feature the iconic ‘Tree of Life’ diagram which he drew on his return from the voyage of the HMS Beagle. The Linnean Society of London holds several of Darwin's letters, manuscripts and books. Here is also home to John Collier’s original iconic portrait of Charles Darwin, commissioned by the Society and painted in 1883 to commemorate the first reading of the theory of evolution by natural selection at a Linnean Society meeting in 1858. At the Natural History Museum, a letter written to his wife Emma in 1844, provides insight into Darwin’s perceived significance of his species theory research and holds instructions on what she should do in the case of his sudden death. This is alongside other letters to Museum staff and other family members which demonstrate the broad scope of his scientific thinking, research and communication ranging from caterpillars to volcanoes, dahlias to ants and the taking of photographs for his third publication Expression of the Emotions in Man and Animals. Correspondence with Darwin’s publisher John Murray, held at the National Library of Scotland document the transformation of his research into print, including the ground-breaking On the Origin of Species publication. At the Royal Botanic Gardens, Kew, documents include a highly significant collection of 44 letters sent around the HMS Beagle expedition from Darwin to Professor John Stevens Henslow, detailing his travels and the genesis of his theory of evolution as he comes in contact with new plants, wildlife and fossils; as well as a rare sketch of the orchid Gavilea patagonica made by Darwin. Other items include a letter from Darwin to his dear friend Joseph Hooker, Director of Kew in which he requests cotton seeds from Kew's collections for his research. Down House (English Heritage) in Kent was both a family home and a place of work where Darwin pursued his scientific interests, carried out experiments, and researched and wrote his many ground-breaking publications until his death in 1882. The extensive collection amassed by Darwin during his 40 years at Down paint a picture of Darwin’s professional and personal life and the intersection of the two. The archive here includes over 200 books from Darwin’s personal collection, account books, diaries, the Journal of the Voyage of the Beagle MSS, and Beagle notebooks and letters. More personal items include scrapbooks, Emma Darwin’s photograph album and Charles Darwin’s will. The collection at Down House has been mainly assembled through the generous donations of Darwin’s descendants. This inscription marks a significant milestone in recognising Darwin’s legacy, as it brings together materials held by multiple institutions across the UK for the first time, ensuring that his work's scientific, cultural, and historical value is preserved for future generations. In line with the ideals of the UNESCO Memory of the World Programme, much of the Darwin archive can be viewed by the public at the partner institutions and locations. The UNESCO International Memory of the World Register includes some of the UK’s most treasured documentary heritage, such as the Domesday Book, the Shakespeare Documents, alongside more contemporary materials, including the personal archive of Sir Winston Churchill. The Charles Darwin archive now joins this esteemed list, underscoring its historical, scientific, and cultural significance. The inscription of the Charles Darwin archive comes as part of UNESCO’s latest recognition of 75 archives worldwide onto the International Memory of the World Register. These newly inscribed collections include a diverse range of documents, such as the Draft of the International Bill of Human Rights, the papers of Friedrich Nietzche, and the Steles of Shaolin Temple (566-1990) in China. Baroness Chapman of Darlington, Minister of State for International Development, Latin America and Caribbean, Foreign, Commonwealth & Development Office (FCDO) said: "The recognition of the Charles Darwin archive on UNESCO's International Memory of the World Register is a proud moment for British science and heritage. "Darwin's work fundamentally changed our understanding of the natural world and continues to inspire scientific exploration to this day. By bringing together extraordinary material from our world class British institutions, this archive ensures that Darwin's groundbreaking work remains accessible to researchers, students, and curious minds across the globe." Ruth Padel, FRSL, FZS, poet, conservationist, great-great-grand-daughter of Charles Darwin and King’s College London Professor of Poetry Emerita, said: "How wonderful to see Darwin’s connections to so many outstanding scientific and cultural institutions in the UK reflected in the recognition of his archive on the UNESCO Memory of the World International Register. All these institutions are open to the public so everyone will have access to his documentary heritage." Dr Jessica Gardner, University Librarian and Director of Library Services at Cambridge University Libraries (CUL) said: "For all Charles Darwin gave the world, we are delighted by the UNESCO recognition in the Memory of the World of the exceptional scientific and heritage significance of his remarkable archive held within eminent UK institutions. "Cambridge University Library is home to over 9,000 letters to and from Darwin, as well as his handwritten experimental notebooks, publications, and photographs which have together fostered decades of scholarship and public enjoyment through exhibition, education for schools, and online access. "We could not be prouder of UNESCO’s recognition of this remarkable documentary heritage at the University of Cambridge, where Darwin was a student at Christ’s College and where his family connections run deep across the city, and are reflected in his namesake, Darwin College." Read the full, illustrated version of this story on the University Library's site.   Documentary heritage relating to the life and work of Charles Darwin has been recognised on the prestigious UNESCO International Memory of the World Register, highlighting its critical importance to global science and the necessity of its long-term preservation and accessibility. We could not be prouder of UNESCO’s recognition of this remarkable documentary heritageJessica GardnerCambridge University LibraryTwo of Charles Darwin’s pocket notebooks in Cambridge University Library The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. 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Scientists at the Medical Research Council (MRC) Mitochondrial Biology Unit, University of Cambridge, have worked out the structure of this machine and shown how it operates like the lock on a canal to transport pyruvate – a molecule generated in the body from the breakdown of sugars – into our mitochondria. Known as the mitochondrial pyruvate carrier, this molecular machine was first proposed to exist in 1971, but it has taken until now for scientists to visualise its structure at the atomic scale using cryo-electron microscopy, a technique used to magnify an image of an object to around 165,000 times its real size. Details are published today in Science Advances. Dr Sotiria Tavoulari, a Senior Research Associate from the University of Cambridge, who first determined the composition of this molecular machine, said: “Sugars in our diet provide energy for our bodies to function. When they are broken down inside our cells they produce pyruvate, but to get the most out of this molecule it needs to be transferred inside the cell’s powerhouses, the mitochondria. There, it helps increase 15-fold the energy produced in the form of the cellular fuel ATP.” Maximilian Sichrovsky, a PhD student at Hughes Hall and joint first author of the study, said: “Getting pyruvate into our mitochondria sounds straightforward, but until now we haven’t been able to understand the mechanism of how this process occurs. Using state-of-the-art cryo-electron microscopy, we’ve been able to show not only what this transporter looks like, but exactly how it works. It’s an extremely important process, and understanding it could lead to new treatments for a range of different conditions.” Mitochondria are surrounded by two membranes. The outer one is porous, and pyruvate can easily pass through, but the inner membrane is impermeable to pyruvate. To transport pyruvate into the mitochondrion, first an outer ‘gate’ of the carrier opens, allowing pyruvate to enter the carrier. This gate then closes, and the inner gate opens, allowing the molecule to pass through into the mitochondrion. “It works like the locks on a canal but on the molecular scale,” said Professor Edmund Kunji from the MRC Mitochondrial Biology Unit, and a Fellow at Trinity Hall, Cambridge. “There, a gate opens at one end, allowing the boat to enter. It then closes and the gate at the opposite end opens to allow the boat smooth transit through.” Because of its central role in controlling the way mitochondria operate to produce energy, this carrier is now recognised as a promising drug target for a range of conditions, including diabetes, fatty liver disease, Parkinson’s disease, specific cancers, and even hair loss. Pyruvate is not the only energy source available to us. Our cells can also take their energy from fats stored in the body or from amino acids in proteins. Blocking the pyruvate carrier would force the body to look elsewhere for its fuel – creating opportunities to treat a number of diseases. In fatty liver disease, for example, blocking access to pyruvate entry into mitochondria could encourage the body to use potentially dangerous fat that has been stored in liver cells. Likewise, there are certain tumour cells that rely on pyruvate metabolism, such as in some types of prostate cancer. These cancers tend to be very ‘hungry’, producing excess pyruvate transport carriers to ensure they can feed more. Blocking the carrier could then starve these cancer cells of the energy they need to survive, killing them. Previous studies have also suggested that inhibiting the mitochondrial pyruvate carrier may reverse hair loss. Activation of human follicle cells, which are responsible for hair growth, relies on metabolism and, in particular, the generation of lactate. When the mitochondrial pyruvate carrier is blocked from entering the mitochondria in these cells, it is instead converted to lactate. Professor Kunji said: “Drugs inhibiting the function of the carrier can remodel how mitochondria work, which can be beneficial in certain conditions. Electron microscopy allows us to visualise exactly how these drugs bind inside the carrier to jam it – a spanner in the works, you could say. This creates new opportunities for structure-based drug design in order to develop better, more targeted drugs. This will be a real game changer.” The research was supported by the Medical Research Council and was a collaboration with the groups of Professors Vanessa Leone at the Medical College of Wisconsin, Lucy Forrest at the National Institutes of Health, and Jan Steyaert at the Free University of Brussels. Reference Sichrovsky, M, Lacabanne, D, Ruprecht, JJ & Rana, JJ et al. Molecular basis of pyruvate transport and inhibition of the human mitochondrial pyruvate carrier. Sci Adv; 18 Apr 2025; DOI: 10.1126/sciadv.adw1489 Fifty years since its discovery, scientists have finally worked out how a molecular machine found in mitochondria, the ‘powerhouses’ of our cells, allows us to make the fuel we need from sugars, a process vital to all life on Earth. Drugs inhibiting the function of the carrier can remodel how mitochondria work, which can be beneficial in certain conditionsEdmund Kunjibob_bosewell (Getty Images)Bald young man, front view The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms. Yes

The ‘Barbarian Conspiracy’ of 367 CE was one of the most severe threats to Rome’s hold on Britain since the Boudiccan revolt three centuries earlier. Contemporary sources indicate that components of the garrison on Hadrian’s wall rebelled and allowed the Picts to attack the Roman province by land and sea. Simultaneously, the Scotti from modern-day Ireland invaded broadly in the west, and Saxons from the continent landed in the south. Senior Roman commanders were captured or killed, and some soldiers reportedly deserted and joined the invaders. Throughout the spring and summer, small groups roamed and plundered the countryside. Britain’s descent into anarchy was disastrous for Rome and it took two years for generals dispatched by Valentian I, Emperor of the Western Roman Empire, to restore order. The final remnants of official Roman administration left Britain some 40 years later around 410 CE. The University of Cambridge-led study, published today in Climatic Change, used oak tree-ring records to reconstruct temperature and precipitation levels in southern Britain during and after the ‘Barbarian Conspiracy’ in 367 CE. Combining this data with surviving Roman accounts, the researchers argue that severe summer droughts in 364, 365 and 366 CE were a driving force in these pivotal events. First author Charles Norman, from Cambridge’s Department of Geography, said: “We don’t have much archaeological evidence for the ‘Barbarian Conspiracy’. Written accounts from the period give some background, but our findings provide an explanation for the catalyst of this major event.” The researchers found that southern Britain experienced an exceptional sequence of remarkably dry summers from 364 to 366 CE. In the period 350 to 500 CE, average monthly reconstructed rainfall in the main growing season (April–July) was 51 mm. But in 364 CE, it fell to just 29mm. 365 CE was even worse with 28mm, and 37mm the following year kept the area in crisis. Professor Ulf Büntgen, from Cambridge’s Department of Geography, said: “Three consecutive droughts would have had a devastating impact on the productivity of Roman Britain’s most important agricultural region. As Roman writers tell us, this resulted in food shortages with all of the destabilising societal effects this brings.” Between 1836 and 2024 CE, southern Britain only experienced droughts of a similar magnitude seven times – mostly in recent decades, and none of these were consecutive, emphasising how exceptional these droughts were in Roman times. The researchers identified no other major droughts in southern Britain in the period 350–500 CE and found that other parts of northwestern Europe escaped these conditions. Roman Britain’s main produce were crops like spelt wheat and six-row barley. Because the province had a wet climate, sowing these crops in spring was more viable than in winter, but this made them vulnerable to late spring and early summer moisture deficits, and early summer droughts could lead to total crop failure. The researchers point to surviving accounts written by Roman chroniclers to corroborate these drought-driven grain deficits. By 367 CE, Ammianus Marcellinus described the population of Britain as in the ‘utmost conditions of famine’. “Drought from 364 to 366 CE would have impacted spring-sown crop growth substantially, triggering poor harvests,” Charles Norman said. “This would have reduced the grain supply to Hadrian’s Wall, providing a plausible motive for the rebellion there which allowed the Picts into northern Britain.” The study suggests that given the crucial role of grain in the contract between soldiers and the army, grain deficits may have contributed to other desertions in this period, and therefore a general weakening of the Roman army in Britain. In addition, the geographic isolation of Roman Britain likely combined with the severity of the prolonged drought to reduce the ability of Rome to alleviate the deficits. Ultimately the researchers argue that military and societal breakdown in Roman Britain provided an ideal opportunity for peripheral tribes, including the Picts, Scotti and Saxons, to invade the province en masse with the intention of raiding rather than conquest. Their finding that the most severe conditions were restricted to southern Britain undermines the idea that famines in other provinces might have forced these tribes to invade. Andreas Rzepecki, from the Generaldirektion Kulturelles Erbe Rheinland-Pfalz, said: “Our findings align with the accounts of Roman chroniclers and the seemingly coordinated nature of the ‘Conspiracy’ suggests an organised movement of strong onto weak, rather than a more chaotic assault had the invaders been in a state of desperation.” “The prolonged and extreme drought seems to have occurred during a particularly poor period for Roman Britain, in which food and military resources were being stripped for the Rhine frontier, while immigratory pressures increased.” “These factors limited resilience, and meant a drought induced, partial-military rebellion and subsequent external invasion were able to overwhelm the weakened defences.” The researchers expanded their climate-conflict analysis to the entire Roman Empire for the period 350–476 CE. They reconstructed the climate conditions immediately before and after 106 battles and found that a statistically significant number of battles were fought following dry years. Tatiana Bebchuk, from Cambridge’s Department of Geography, said: “The relationship between climate and conflict is becoming increasingly clear in our own time so these findings aren’t just important for historians. Extreme climate conditions lead to hunger, which can lead to societal challenges, which eventually lead to outright conflict.” Charles Norman, Ulf Büntgen, Paul Krusic and Tatiana Bebchuk are based at the Department of Geography, University of Cambridge; Lothar Schwinden and Andreas Rzepecki are from the Generaldirektion Kulturelles Erbe Rheinland-Pfalz in Trier. Ulf Büntgen is also affiliated with the Global Change Research Institute, Czech Academy of Sciences and the Department of Geography, Masaryk University in Brno. Reference C Norman, L Schwinden, P Krusic, A Rzepecki, T Bebchuk, U Büntgen, ‘Droughts and conflicts during the late Roman period’, Climatic Change (2025). DOI: 10.1007/s10584-025-03925-4 Funding Charles Norman was supported by Wolfson College, University of Cambridge (John Hughes PhD Studentship). Ulf Büntgen received funding from the Czech Science Foundation (# 23-08049S; Hydro8), the ERC Advanced Grant (# 882727; Monostar), and the ERC Synergy Grant (# 101118880; Synergy-Plague). Three consecutive years of drought contributed to the ‘Barbarian Conspiracy’, a pivotal moment in the history of Roman Britain, a new Cambridge-led study reveals. Researchers argue that Picts, Scotti and Saxons took advantage of famine and societal breakdown caused by an extreme period of drought to inflict crushing blows on weakened Roman defences in 367 CE. While Rome eventually restored order, some historians argue that the province never fully recovered. Our findings provide an explanation for the catalyst of this major event.Charles NormanAdam CuerdenMilecastle 39 on Hadrian's Wall The text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright ©University of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms. YesLicence type: Public Domain