Snoozing, or using intermittent alarms to get in a few more minutes of sleep in the morning, may have benefits for some people, according to research published in the Journal of Sleep Research.
In a study of 1732 adults who described their waking habits, 69% of participants reported using the snooze function or setting multiple alarms at least “sometimes.” In those who snoozed, the average time spent snoozing per morning was 22 minutes, ranging from 1 to 180 minutes. Snoozers tended to be younger than non-snoozers and were more likely to be evening types. Morning drowsiness and shorter sleep were also more common in those who snoozed.
In a second study of 31 habitual snoozers, 30 minutes of snoozing improved or did not affect performance on cognitive tests directly upon rising compared with waking up abruptly. Snoozing resulted in about 6 minutes of lost sleep, but it prevented awakening from slow-wave sleep. There were no clear effects of snoozing on stress hormone levels, morning sleepiness, mood, or overnight sleep structure.
“The findings indicate that there is no reason to stop snoozing in the morning if you enjoy it, at least not for snooze times around 30 minutes. In fact, it may even help those with morning drowsiness to be slightly more awake once they get up,” said corresponding author Tina Sundelin, PhD, of Stockholm University.
University of Bristol researchers have created a robotic hand that could carry out Clinical Breast Examinations (CBE). The device is able to apply very specific forces over a range similar to forces used by human examiners and can detect lumps using sensor technology at larger depths than before.
This could revolutionise how women monitor their breast health by giving them access to safe electronic CBEs, located in easily accessible places, such as pharmacies and health centres, which provide accurate results. The technology is described in the journal Sensors.
Precision, repeatability and accuracy are of paramount importance in these tactile medical examinations to ensure favourable patient outcomes. A range of automatic and semi-automatic devices have been proposed to aid with optimising this task, particularly for difficult to detect and hard to reach situations such as during minimally invasive surgery.
The research team included a mix of postgraduate and undergraduate researchers, supervised by Dr Antonia Tzemanaki from Bristol Robotics Laboratory. Lead author George Jenkinson explained: “There are conflicting ideas about how useful carrying out Clinical Breast Examinations (CBE) are for the health outcomes of the population.
“It’s generally agreed upon that if it is well performed, then it can be a very useful and low risk diagnostic technique.
“There have been a few attempts in the past to use technology to improve the standard to which healthcare professionals can perform a CBE by having a robot or electronic device physically palpate breast tissue. But the last decade or so of technological advances in manipulation and sensor technology mean that we are now in a better position to do this.
“The first question that we want to answer as part of this is whether a specialised manipulator can be demonstrated to have the dexterity necessary to palpate a realistic breast size and shape.”
The team created their manipulator using 3D printing and other Computerised Numerical Control techniques and employed a combination of laboratory experiments and simulated experiments on a fake (silicone) breast and its digital twin, both modelled on a volunteer at the Simulation and Modelling in Medicine and Surgery research group at Imperial College London.
The simulations allowed the team to perform thousands of palpations and test lots of hypothetical scenarios such as calculating the difference in efficiency when using two, three, or four sensors at the same time. In the lab, they were able to carry out the experiments on the silicone breast to demonstrate the simulations were accurate and to experimentally discover the forces for the real equipment.
George added: “We hope that the research can contribute to and complement the arsenal of techniques used to diagnose breast cancer, and to generate a large amount of data associated with it that may be useful in trying to identify large scale trends that could help diagnose breast cancer early.
“One advantage that some doctors have mentioned anecdotally is that this could provide a low-risk way to objectively record health data. This could be used, for example, to compare successive examinations more easily, or as part of the information packet sent to a specialist if a patient is referred for further examination.”
As a next step, the team will combine CBE techniques learned from professionals with AI, and fully equip the manipulator with sensors to determine the effectiveness of the whole system at identifying potential cancer risks.
The ultimate goal is that the device and sensors will have the capability to detect lumps more accurately and deeper than it is possible only from applying human touch. It could also be combined with other existing techniques, such as ultrasound examination.
“So far we have laid all of the groundwork,” said George. “We have shown that our robotic system has the dexterity necessary to carry out a clinical breast examination – we hope that in the future this could be a real help in diagnosing cancers early.”
In the early 1900s, Japanese scientist Kikunae Ikeda first proposed umami as a basic taste in addition to sweet, sour, salty and bitter. About eight decades later, the scientific community officially agreed with him. Now, scientists led by researchers at the USC Dornsife College of Letters, Arts and Sciences have evidence of a sixth basic taste, which fans of salt licorice will recognise.
In research published in Nature Communications, USC Dornsife neuroscientist Emily Liman and her team found that the tongue responds to ammonium chloride through the same protein receptor that signals sour taste.
Salt licorice has been a popular sweet in northern European countries since at least since the early 20th century, and also appears on South African shelves. The treat counts among its ingredients salmiak salt, or ammonium chloride.
Scientists have for decades recognised that the tongue responds strongly to ammonium chloride. However, despite extensive research, the specific tongue receptors that react to it remained elusive.
Liman and the research team thought they might have an answer. In recent years, they uncovered the protein responsible for detecting sour taste. That protein, called OTOP1, sits within cell membranes and forms a channel for hydrogen ions moving into the cell.
Hydrogen ions are the key component of acids, and as foodies everywhere know, the tongue senses acid as sour, such as the citric acid in lemon juice. Hydrogen ions from these acidic substances move into taste receptor cells through the OTOP1 channel.
Because ammonium chloride can affect the concentration of acid – that is, hydrogen ions – within a cell, the team wondered if it could somehow trigger OTOP1.
To answer this question, they introduced the Otop1 gene into lab-grown human cells so the cells produce the OTOP1 receptor protein. They then exposed the cells to acid or to ammonium chloride and measured the responses.
“We saw that ammonium chloride is a really strong activator of the OTOP1 channel,” Liman said. “It activates as well or better than acids.”
Ammonium chloride gives off small amounts of ammonia, which moves inside the cell and raises the pH, meaning fewer hydrogen ions.
“This pH difference drives a proton influx through the OTOP1 channel,” explained Ziyu Liang, a PhD student in Liman’s lab and first author on the study.
To confirm that their result was more than a laboratory artifact, they turned to a technique that measures electrical conductivity, simulating how nerves conduct a signal. Using taste bud cells from normal mice and from mice the lab previously genetically engineered to not produce OTOP1, they measured how well the taste cells generated electrical responses called action potentials when ammonium chloride is introduced.
Taste bud cells from wildtype mice showed a sharp increase in action potentials after ammonium chloride was added while taste bud cells from the mice lacking OTOP1 failed to respond to the salt. This confirmed their hypothesis that OTOP1 responds to the salt, generating an electrical signal in taste bud cells.
The same was true when another member of the research team, Courtney Wilson, recorded signals from the nerves that innervate the taste cells. She saw the nerves respond to addition of ammonium chloride in normal mice but not in mice lacking OTOP1.
Then the team went one step further and examined how mice react when given a choice to drink either plain water or water laced with ammonium chloride. For these experiments, they disabled the bitter cells that also contribute to the taste of ammonium chloride. Mice with a functional OTOP1 protein found the taste of ammonium chloride unappealing and did not drink the solution, while mice lacking the OTOP1 protein did not mind the alkaline salt, even at very high concentrations.
“This was really the clincher,” Liman said. “It shows that the OTOP1 channel is essential for the behavioral response to ammonium.”
But the scientists weren’t done. They wondered if other animals would also be sensitive to and use their OTOP1 channels to detect ammonium. They found that the OTOP1 channel in some species seems to be more sensitive to ammonium chloride than in other species. And human OTOP1 channels were also sensitive to ammonium chloride.
So, what is the advantage in tasting ammonium chloride and why is it evolutionarily so conserved?
Liman speculates that the ability to taste ammonium chloride might have evolved to help organisms avoid eating harmful biological substances that have high concentrations of ammonium.
“Ammonium is found in waste products – think of fertiliser – and is somewhat toxic,” she explained, “so it makes sense we evolved taste mechanisms to detect it. Chicken OTOP1 is much more sensitive to ammonium than zebra fish.” Liman speculates that these variations may reflect differences in the ecological niches of different animals. “Fish may simply not encounter much ammonium in the water, while chicken coops are filled with ammonium that needs to be avoided and not eaten.”
But she cautions that this is very early research and further study is needed to understand species differences in sensitivity to ammonium and what makes OTOP1 channels from some species sensitive and some less sensitive to ammonium.
Towards this end, they have made a start. “We identified a particular part of the OTOP1 channel – a specific amino acid – that’s necessary for it to respond to ammonium,” Liman said. “If we mutate this one residue, the channel is not nearly as sensitive to ammonium, but it still responds to acid.”
Moreover, because this one amino acid is conserved across different species, there must have been selective pressure to maintain it, she says. In other words, the OTOP1 channel’s ability to respond to ammonium must have been important to the animals’ survival.
In the future, the researchers plan to extend these studies to understand whether sensitivity to ammonium is conserved among other members of the OTOP proton family, which are expressed in other parts of the body, including in the digestive tract.
And who knows? Perhaps ammonium chloride will join the other five basic tastes to bring the official count to six.
Researchers have used wearable technology to measure electrical impulses in the skin and other physiological biomarkers possibly linked to mood changes in bipolar disorder. Though at an early stage, they hope their work will be able to build on these patterns to detect mood swings in bipolar disorder sufferers, so helping in diagnosis and potentially offering more rapid and personalised treatments. They presented their research at the 36th ECNP Congress in Barcelona, and more information is available on GitHub.
Bipolar disorder (formerly called manic-depressive illness or manic depression) is a mental illness that causes swings in a person’s mood, energy, activity levels, and concentration. These shifts can make it difficult to carry out day-to-day tasks and can make interactions with other people difficult. The degree of mood swing can vary from person to person, from feeling manic (very “up”) to feeling depressed. At present, these mood swings are mostly diagnosed subjectively, through interview with doctors or by questionnaires. This takes time, and requires an immediate medical presence.
Now a group of Barcelona-based psychiatrists, in collaboration with data scientist in Edinburgh, have used a research grade wearable device to continuously collect several physiological biomarkers during the diverse phases and episodes of bipolar disorder. Among the collected physiological biomarkers is electrodermal activity which uses changes in the skin’s electrical conductivity to indicate the level of stress through the reactivity of the nervous system. This is a potential immediate indicator of whether someone is in a manic, depressive or in a normal mood state.
They recruited 38 patients with bipolar disorder, and 19 healthy controls, all from the Barcelona area.
Researcher Diego Hidalgo-Mazzei said “Each participant was fitted with a commercially available Empatica E4 bracelet, which they were asked to wear for around 48 hours. This can measure a variety of physiological changes, but we were most interested in measuring small electrophysiological changes in the skin of the wearer. We found that bipolar disorder patients in their depressed phase had on average a significantly lower skin electrical activity than the rest of the bipolar group or the healthy control group. We also found that as an individual moved from manic to depressive state (or vice versa), this was detectable by a change in skin surface electrical activity.
“It is important for the patient and doctor to know how and when these mood fluctuations take place. It is important also to highlight that the treatment is different for manic or depressive states. This can help with a prompt diagnosis and early personalized treatment, but it can also help in preventing adverse outcomes, for example in alerting to an increased risk of suicide, or of mood swings which may lead to dangers with activities such as driving. It is also easier to treat patients if we know if they are in a manic phase or a depressed phase. Until now, these mood swings have mostly been diagnosed subjectively, through interview with doctors or by questionnaires, and this had led to real difficulties. Arriving at the correct drug is difficult, with only around 30 to 40% of treated individuals having the expected response. We hope that the additional information these systems can provide will give us greater certainty in treating patients.
“We are still some way from that though. This is an exploratory observational study, so we need to look at a larger sample and use machine learning to analyse all the biomarkers collected by the wearers to confirm the findings to determine patterns which might indicate a specific episode. This may not be ideal for every bipolar disorder sufferer, in every circumstance, but a potential pattern may help in the future the people hardest hit by the mood changes which affect their lives”.
Improved modelling of male and female livers can help lead to safer drugs
Photo by Danilo Alvesd on Unsplash
Researchers report in PLOS Computational Biology that they developed a powerful new tool to understand how medications affect men and women differently, and that will help lead to safer, more effective drugs in the future.
Women are known to suffer a disproportionate number of liver problems from medications but also usually underrepresented in drug testing. To address this, University of Virginia scientists have developed sophisticated computer simulations of male and female livers and used them to reveal sex-specific differences in how the tissues are affected by drugs.
The new model has already provided unprecedented insights into the biological processes that take place in the liver, the organ responsible for detoxifying the body, in both men and women. But the model also represents a powerful new tool for drug development, helping ensure that new medications will not cause harmful side effects.
“There are incredibly complex networks of genes and proteins that control how cells respond to drugs,” said UVA researcher Jason Papin, PhD, one of the model’s creators. “We knew that a computer model would be required to try to answer these important clinical questions, and we’re hopeful these models will continue to provide insights that can improve healthcare.”
Harmful side effects
Papin, of UVA’s Department of Biomedical Engineering, developed the model in collaboration with Connor Moore, a PhD student, and Christopher Holstege, MD, a UVA emergency medicine physician and director of UVA Health’s Blue Ridge Poison Center. “It is exceedingly important that both men and women receive the appropriate dose of recommended medications,” Holstege noted. “Drug therapy is complex and toxicity can occur with subtle changes in dose for specific individuals.”
Before developing their model, the researchers first looked at the federal Food and Drug Administration’s Adverse Event Reporting System to evaluate the frequency of reported liver problems in men and women. The scientists found that women consistently reported liver-related adverse events more often than did men.
The researchers then sought to explain why this might be the case. To do that, they developed computer models of the male and female livers that integrated vast amounts of data on gene activity and metabolic processes within cells. These cutting-edge liver simulations provided important insights into how drugs (xenobiotics) affect the tissue differently in men and women and allowed the researchers to understand why.
They found that xenobiotic metabolism was more active in untreated males, while pentose and glucoronate interconversions were female-biased, suggesting a difference in pretreatment gene expression, which may result in different initial responses of phase I and phase II metabolism to hepatotoxic drugs. They also observed sex-bias in bile acid biosynthesis, which in combination with xenobiotic metabolism, this result may suggest differences in bacterial deconjugation driven by sex differences in the gut microbiome. Differences were also found in several essential metabolic pathways, such as glycolysis/gluconeogenesis, nucleotide metabolism, and lipid metabolism with supporting evidence in human or rat hepatocytes.
“We were surprised how many differences we found, especially in very diverse biochemical pathways,” said Moore, a biomedical engineering student in Papin’s lab. “We hope our results emphasise how important it is for future scientists to consider how both men and women are affected by their research.”
The work has already identified a key series of cellular processes that explain sex differences in liver damage, and the scientists are calling for more investigation of it to better understand “hepatotoxicity” — liver toxicity. Ultimately, they hope their model will prove widely useful in developing safer drugs.
“We’re hopeful these approaches will be help address many other questions where men and women have differences in drug responses or disease processes,” Papin said. “Our ability to build predictive computer models of complex systems in biology, like those in this study, is truly opening all kinds of new avenues for tackling some of the most challenging biomedical problems.”
Interfaces for DoF augmentation (figure by Tobias Pistohl). From Eden at al., Nature Communications. 2022
Busy doctors and nurses may have often found themselves wishing they had an extra arm to help with a patient or help with a difficult suture. Researchers around the world are developing supernumerary robotic arms to help workers achieve certain tasks unaided, or with less strain – but how long would it take to master learning an additional limb? The answer is: not long at all. One hour’s worth of training is enough for people to carry out a task with their ‘third arm’ as effectively as with a partner, according to the results of a new study published in IEEE Open Journal of Engineering in Medicine and Biology.
A new study by researchers at Queen Mary University of London, Imperial College London and The University of Melbourne has found that people can learn to use supernumerary robotic arms as effectively as working with a partner in just one hour of training.
The study investigated the potential of supernumerary robotic arms to help people perform tasks that require more than two hands. The idea of human augmentation with additional artificial limbs has long been a staple of science fiction.
Demonstrating performing a suture with an assistant robotic arm.
“Many tasks in daily life, such as opening a door while carrying a big package, require more than two hands,” said Dr Ekaterina Ivanova, lead author of the study from Queen Mary University of London. “Supernumerary robotic arms have been proposed as a way to allow people to do these tasks more easily, but until now, it was not clear how easy they would be to use.”
The study involved 24 participants who were asked to perform a variety of tasks with a supernumerary robotic arm. The participants were either given one hour of training in how to use the arm, or they were asked to work with a partner.
The results showed that the participants who had received training on the supernumerary arm performed the tasks just as well as the participants who were working with a partner. This suggests that supernumerary robotic arms can be a viable alternative to working with a partner, and that they can be learned to use effectively in a relatively short amount of time.
“Our findings are promising for the development of supernumerary robotic arms,” said Dr Ivanova. “They suggest that these arms could be used to help people with a variety of tasks, such as surgery, industrial work, or rehabilitation.”
Researchers have reported in Circulation that the vagus nerve, known for its parasympathetic role in ‘resting and digesting’, also has an important role in exercise, helping the heart pump blood.
Exercise science currently holds that the ‘fight or flight’ (sympathetic) nervous system is active during exercise, helping the heart beat harder, and the ‘rest and digest’ (parasympathetic) nervous system is lowered or inactive. However, University of Auckland physiology Associate Professor Rohit Ramchandra says that this current understanding is based on indirect estimates and a number of assumptions which this new study has proven to be wrong.
“Our study finds the activity in these ‘rest and digest’ vagal nerves actually increases during exercise,” Dr Ramchandra says. “Our group has used ‘tour de force’ electrical recording techniques to directly monitor vagal nerve activity in exercising sheep and has found the activity in these vagal nerves going to the heart increases during exercise.
”For the heart to sustain a high level of pumping, it needs a greater blood flow during exercise to fuel the increased work it is doing: our data indicate that the increase in vagal activity does just this.”
During exercise, there is a four to five-fold increase in the amount of blood pumped out by the heart per minute, requiring increased cardiac output. This is modulated by autonomic nerves that travel from the brain, including the sympathetic and parasympathetic vagal nerves.
The vagal nerve connects the brain to the heart, and other internal organs including the gut, regulating the ‘rest and digest’ parasympathetic nervous system responses. The new research finds the parasympathetic and sympathetic nervous systems work together in exercise to help increase cardiac output. The researchers also investigated the role of mediators released by the cardiac vagal nerve.
“The cardiac vagus nerve releases multiple mediators, and previous research has focused on a neurotransmitter, acetylcholine, which has no impact on our ability to exercise,” says Dr Ramchandra. “Our study focused on a different mediator, vasoactive intestinal peptide (VIP) and it shows that the vagus nerve releases this peptide during exercise, which helps the coronary vessels dilate allowing more blood to pump through the heart.”
The first and co-corresponding author Dr Julia Shanks says, “Vasoactive intestinal peptide was first found in the gut and it does help in digestion, but what we now know is that it is also important in exercise.”
The trial was conducted in sheep, because of their similarity to humans in many important respects including cardiac anatomy and physiology. They are also well-established as an animal model to assist with finding ways to combat heart disease that translate to humans.
These fundamental findings could have applications in diseases, including heart failure, where people cannot tolerate exercise.
“This inability to carry out simple tasks involving exertion means that quality of life is severely compromised in these patients,” Dr Ramchandra says. “One potential reason why exercise tolerance is reduced is that the diseased heart simply does not receive enough blood. Our follow-up study will try to see whether we can use this important role of cardiac vagal nerves to improve exercise tolerance in heart failure.”
There is a lot of interest in trying to ‘hack’ or improve vagal tone as a means to reduce anxiety. Investigating this was outside the scope of the current study.
Dr Ramchandra says we do know that the vagus mediates the slowing down of heart rate and if we have high vagal activity, then our hearts should beat slower.
“Whether this is the same as relaxation, I am not sure, but we can say that regular exercise can improve vagal activity and has beneficial effects.”
‘Long COVID’ is a mysterious constellation of symptoms associated with having recovered from COVID infection – but how many cases represent a true condition, and how many fall under a poorly-defined umbrella of currently known ones? Overly broad definitions, a lack of appropriate, or any, comparison groups, among other things, in studies looking at the epidemiology of the condition have distorted the risks, say the authors of a review published in BMJ Evidence-based Medicine.
This is further compounded by inclusion of poorly conducted studies into systematic reviews and pooled data analyses that end up overstating the risk yet again, they add.
Likely consequences include increased public anxiety and healthcare spend; misdiagnoses; and diversion of funds from those who really do have other long term conditions secondary to COVID infection, suggest the researchers.
Many after-effects of COVID infection include post-ICU syndrome, which is a constellation of health issues that are present when the patient is in intensive care and which persist after discharge home, and shortness of breath following pneumonia. The trouble is that these are common to many upper respiratory viruses, the researchers point out.
None of the working definitions of ‘long COVID’ used by influential health bodies, such as the US Centers for Disease Control and Prevention, the World Health Organization, the UK National Institute for Health and Care Excellence (NICE), Scottish Intercollegiate Guidelines Network (SIGN), and the Royal College of General Practitioners requires a causal link between SARS-CoV2 and a range of symptoms.
Not only should comparator (control) groups be included in ‘long COVID’ studies, when they often aren’t, but they should also be properly matched to cases, ideally by age, sex, geography, socioeconomic status and, if possible, underlying health and health behaviours, which they rarely are, say the researchers.
During the early stages of the pandemic, when SARS-CoV-2 testing wasn’t widely available, studies were more likely to include a non-representative sample of SARS-CoV-2-positive patients by including fewer patients with mild or no symptoms.
This is known as sampling bias, which occurs when certain members of a population have a higher probability of being included in a study sample than others, potentially limiting the generalisability of a study’s findings, explain the researchers.
“Our analysis indicates that, in addition to including appropriately matched controls, there is a need for better case definitions and more stringent [‘long COVID’] criteria, which should include continuous symptoms after confirmed SARS-CoV-2 infection and take into consideration baseline characteristics, including physical and mental health, which may contribute to an individual’s post COVID experience, “ they write, adding that the umbrella term ‘long COVID’ should be jettisoned in favour of different terms for specific after effects.
While the results of high quality population studies on ‘long COVID’ in adults and children have been reassuring, they point out, the body of research “is replete with studies with critical biases” they add, setting out common pitfalls.
“Ultimately, biomedicine must seek to aid all people who are suffering. In order to do so, the best scientific methods and analysis must be applied. Inappropriate definitions and flawed methods do not serve those whom medicine seeks to help,” they insist.
“Improving standards of evidence generation is the ideal method to take long COVID seriously, improve outcomes, and avoid the risks of misdiagnosis and inappropriate treatment,” they include.
Using data from a consumer sleep tracker, a new study has shown that not only do people in Asia go to sleep later and have shorter sleep, they also have lower sleep quality than those in other parts of the world. The study, published in Sleep Medicine, also showed that South Africans, Australians and New Zealanders went to bed and rose earlier than the other parts of the world included in the research, but also got the most sleep.
This finding surfaced after a team of researchers from the Centre for Sleep and Cognition at the Yong Loo Lin School of Medicine, National University of Singapore (NUS Medicine) in partnership with Oura Health Oy (Finland), analysed 50 million nights of anonymised sleep data, contributed by over 220 000 users of the “Oura Ring”, a consumer sleep tracker, from across 35 countries. Most of the users were working adults, aged between 30 and 55 years. To provide a comprehensive analysis of sleep measures for each user, the team gathered sleep data from multiple nights across a whole year – on average, each user contributed 242 nights of data. Weekday and weekend sleep were analysed separately to assess the impact of the working week on sleep patterns.
The results showed that people in Asia have shorter sleep, and display higher variability in both sleep timing and duration on weekdays. They also fall asleep later than those living in Europe, Oceania and North America. Previous studies have shown that shorter sleep duration is usually associated with higher sleep efficiency as people try to make the most of their sleep opportunity; however, in this study, despite sleeping less, people in Asia also had lower sleep efficiency. This may be because factors that result in short sleep (eg, work-related anxiety) also lead to lower quality sleep.
People often sleep for longer at the weekends than during the week, a phenomenon known as weekend sleep extension. While there was a clear association between shorter weekday sleep and longer weekend sleep extension, suggesting that people caught up on sleep at the weekend, even after accounting for this, people in Asia had the shortest weekend sleep extension.
While there are many socio-cultural factors that affect sleep patterns, the team hypothesises that because it plays such a fundamental role in our lives, work (and the broader work culture) is one of the most influential factors affecting how we sleep. Previous evidence from time use studies have demonstrated a strong association between long work hours and short sleep. Additionally, there is evidence that preoccupation with work demands and the inability to stop thinking about work contribute to sleep disturbances.
Dr Adrian Willoughby, Senior Research Fellow at NUS Medicine’s Centre for Sleep and Cognition, said, “In Europe, weekends are generally considered time for relaxation, and engaging in social activities with friends and family. In Asia, however, people may use the weekends to catch up on work, do the things they didn’t have time for during the week or attend to more family responsibilities. We think that longer working hours and the difference in work culture in Asia means that people don’t catch up on sleep as much at the weekends, but try to catch up whenever they have the opportunity over the course of the week.”
Prof Michael Chee, Director of the Centre for Sleep and Cognition at NUS Medicine said, “Sleep is a significant issue to address, especially for people living in Asia, who seem to sleep less than other global regions. Access to such a large dataset has allowed us to have unique insights into global sleep patterns. This research enables us to work towards our goal of giving customised sleep advice that considers individual sleep needs, environment factors and larger socio-cultural pressures that affect sleep. We want people to practise sleep routines that fit different contexts, but also promote health, well-being and performance.”
Singapore scientists have developed a flexible battery as thin as a human cornea, which can store electricity when immersed in a saline solution such as tears. The scientists described their research in Nano Energy, and believe that this technology could one day power smart contact lenses.
Smart contact lenses are high-tech contact lenses capable of displaying visible information on the cornea and can be used to access augmented reality as well as monitoring health and their normal function of correcting vision. But they need power, and existing rechargeable batteries rely on wires or induction coils that contain metal and are unsuitable for use in the human eye, as they are uncomfortable and present risks to the user.
The battery, developed by Nanyang Technological University, is made of biocompatible materials and does not contain wires or toxic heavy metals, such as those in lithium-ion batteries or wireless charging systems. It has a glucose-based coating that reacts with the sodium and chloride ions in the saline solution surrounding it, while the water the battery contains serves as the ‘wire’ or ‘circuitry’ for electricity to be generated.
The battery could also be powered by human tears as they contain sodium and potassium ions, at a lower concentration. Testing the current battery with a simulated tear solution, the researchers showed that the battery’s life would be extended an additional hour for every twelve-hour wearing cycle it is used. The battery can also be charged conventionally by an external power supply.
Associate Professor Lee Seok Woo, from NTU’s School of Electrical and Electronic Engineering (EEE), who led the study, said: “This research began with a simple question: could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.
“However, previous techniques for lens batteries were not perfect as one side of the battery electrode was charged and the other was not. Our approach can charge both electrodes of a battery through a unique combination of enzymatic reaction and self-reduction reaction. Besides the charging mechanism, it relies on just glucose and water to generate electricity, both of which are safe to humans and would be less harmful to the environment when disposed, compared to conventional batteries.”
The research team has filed for a patent through NTUitive, NTU’s innovation and enterprise company. They are also working towards commercialising their invention.
Cry me a current
The team demonstrated their invention using a simulated human eye. The battery, which is about 0.5 millimetres-thin generates electrical power by reacting with the basal tears – the constant tears that create a thin film over our eyeballs – for the devices embedded within the lenses to function.
The flexible and flat battery discharges electricity through a process called reduction when its glucose oxidase coating reacts with the sodium and chloride ions in the tears, generating power and current within the contact lenses.
The team demonstrated that the battery could produce a current of 45 microamperes and a maximum power of 201 microwatts, which would be sufficient to power a smart contact lens.
Laboratory tests showed that the battery could be charged and discharged up to 200 times. Typical lithium-ion batteries have a lifespan of 300 to 500 charging cycles.
The team recommends that the battery should be placed for at least eight hours in a suitable solution that contains a high quantity of glucose, sodium and potassium ions, to be charged while the user is asleep.
