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Washington D.C, Feb 10: Children's vulnerability towards depression, anxiety, impulsive behaviour, and poor cognitive performance could be determined by considering the hours of sleep they manage to get.

Sleep states are active processes that support the reorganisation of brain circuitry. This makes sleep especially important for children, whose brains are developing and reorganising rapidly.

In a study by researchers from the University of Warwick -- recently published in the journal Molecular Psychiatry -- cases of 11,000 children aged between 9 and 11 years from the Adolescent Brain Cognitive Development dataset were analyzed to find out the relationship between sleep duration and brain structure.

The study was carried out by researchers Professor Jianfeng Feng, Professor Edmund Rolls, Dr. Wei Cheng and colleagues from the University of Warwick's Department of Computer Science and Fudan University.

Measures of depression, anxiety, impulsive behaviour and poor cognitive performance in the children were associated with shorter sleep duration. Moreover, the depressive problems were associated with short sleep duration one year later.

The reduced brain volume of areas such as orbitofrontal cortex, prefrontal, and temporal cortex, precuneus, and supramarginal gyrus was found to be associated with the shorter sleep duration.

Professor Jianfeng Feng, from the University of Warwick's Department of Computer Science, comments: "The recommended amount of sleep for children 6 to 12 years of age is 9-12 hours. However, sleep disturbances are common among children and adolescents around the world due to the increasing demand on their time from school, increased screen time use, and sports and social activities."

A previous study showed that about 60 per cent of adolescents in the United States receive less than eight hours of sleep on school nights.

Professor Jianfeng Feng further added: "Our findings showed that the total score for behavior problems in children with less than 7 hours sleep was 53 per cent higher on average and the cognitive total score was 7.8 per cent lower on average than for children with 9-11 hours of sleep. It highlights the importance of enough sleep in both cognition and mental health in children."

Professor Edmund Rolls from the University of Warwick's Department of Computer Science also commented: "These are important associations that have been identified between sleep duration in children, brain structure, and cognitive and mental health measures, but further research is needed to discover the underlying reasons for these relationships."

17-year-old Pratyusha Jha, wakes up scrambling for newspapers these days to look for any news about her pending board exams and is anxious about what the future has in store for her.

Similar concerns are shared by Bipin Kumar, a class 12 student, who says the announcement of board exams from July 1 to 15 brought limited clarity as the larger questions remain unanswered.

The COVID-19 lockdown, came with a different set of concerns for class 12 students, whose board exams were postponed midway following the outbreak of coronavirus, putting on hold their future plans as well.

"Everyday I have been looking for news about the exams and about entrance exam dates. I feel unfortunate that this happened during the year I was supposed to take the big college leap. I don't want my future decisions to be shaped by this very year as what I opt to study now will remain with me lifelong," Pratyusha told PTI.

Ending some uncertainty for students, HRD Minister Ramesh Pokhriyal 'Nishank' on Friday announced that the pending class 10 and 12 board exams will be held from July 1 to 15. While class 12 exams will be conducted across the country, the class 10 exams are only pending in North East Delhi where they were affected due to the law and order situation.

"The anxiety doesn't end here, there is no date sheet yet. What will be the modalities of exams, how will we reach centres, what protocols have to be followed, there is no clarity on that. My friends and I keep calling our school teachers and also the CBSE helpline to seek some clarity," Bipin Kumar said.

Vaibhav Sharma, a class 12 student in Gurgaon said, "There is no clarity yet. I wanted to apply for DU, but now that the exams are taking place in July when will the results be declared, when will cut offs be announced. If I don't get a good college here, will I be able to travel to different cities for admission, nothing is known yet."

Similarly, for the students in northeast Delhi, the wait for the exams has become a "test of patience" as they were postponed first in the area due to law and order situation, and later due to the coronavirus outbreak, resulting in a four-month-long wait for the exams.

"It has become an endless wait and now I don't feel like studying too. Right from childhood, we are taught that board exams are too crucial and have to be focussed at least two years in advance. But now, it is a different picture altogether," Rani Kumari, a resident of Chandbagh said.

Universities and schools across the country have been closed and exams postponed since March 16 when the Centre announced a countrywide classroom shutdown as one of the measures to contain the COVID-19 outbreak.

Later, a nationwide lockdown was announced on March 24, which has now been extended till May 17.

The board was not able to conduct class 10 and 12 exams on eight examination days due to the coronavirus outbreak. Further, due to the law and order situation in North East Delhi, the board was not able to conduct exams on four examination days, while a very small number of students from and around this district were not able to appear in exams on six days.

The board had last month announced that it will only conduct pending exams in 29 subjects which are crucial for promotion and admission to higher educational institutions. The modalities of assessment for the subjects for which exams are not being conducted will be announced soon by the board.

The schedule has been decided in order to ensure that the board exams are completed before competitive examinations such as engineering entrance JEE-Mains, which is scheduled from July 18-23, and medical entrance exam NEET, which is scheduled on July 26.

The University Grants Commission (UGC) has issued guidelines to universities that new academic session for freshers will begin from September while for the existing students from August.

The American pharmaceutical giant Pfizer Inc. and the European biotechnology company BioNTech SE have conducted an experimental trial of a COVID-19 vaccine candidate and found it to be safe, well-tolerated, and capable of generating antibodies in the patients.

The study, which is yet to be peer-reviewed, describes the preliminary clinical data for the candidate vaccine -- nucleoside-modified messenger RNA (modRNA), BNT162b1.

It said the amount of antibodies produced in participants after they received two shots of the vaccine candidate was greater than that reported in patients receiving convalescent plasma from recovered COVID-19 patients.

"I was glad to see Pfizer put up their phase 1 trial data today. Virus neutralizing antibody titers achieved after two doses are greater than convalescent antibody titers," tweeted Peter Hotez, a vaccine scientist from Baylor College of Medicine in the US, who was unrelated to the study.

Researchers, including those from New York University in the US, who were involved in the study, said the candidate vaccine enables human cells to produce an optimised version of the receptor binding domain (RBD) antigen -- a part of the spike (S) protein of SARS-CoV-2 which it uses to gain entry into human cells.

"Robust immunogenicity was observed after vaccination with BNT162b1," the scientists noted in the study.

They said the program is evaluating at least four experimental vaccines, each of which represents a unique combination of mRNA format and target component of the novel coronavirus, SARS-CoV-2.

Based on the study's findings, they said BNT162b1 could be administered in a quantity that was well tolerated, potentially generating a dose dependent production of immune system molecules in the patients.

The research noted that patients treated with the vaccine candidate produced nearly 1.8 to 2.8 fold greater levels of RBD-binding antibodies that could neutralise SARS-CoV-2.

"We are encouraged by the clinical data of BNT162b1, one of four mRNA constructs we are evaluating clinically, and for which we have positive, preliminary, topline findings," said Kathrin U. Jansen, study co-author and Senior Vice President and Head of Vaccine Research & Development, Pfizer.

"We look forward to publishing our clinical data in a peer-reviewed journal as quickly as possible," Jansen said.

According to Ugur Sahin, CEO and Co-founder of BioNTech, and another co-author of the study, the preliminary data are encouraging as they provide an initial signal that BNT162b1 is able to produce neutralising antibody responses in humans.

He said the immune response observed in the patients treated with the experimental vaccine are at, or above, the levels observed from convalescent sera, adding that it does so at "relatively low dose levels."

"We look forward to providing further data updates on BNT162b1," Sahin said.

According to a statement from Pfizer, the initial part of the study included 45 healthy adults 18 to 55 years of age.

It said the priliminary data for BNT162b1 was evaluated in 24 subjects who received two injections of 10 microgrammes ( g) and 30 g -- 12 subjects who received a single injection of 100 g, and 9 subjects who received two doses of a dummy vaccine.

The study noted that participants received two doses, 21 days apart, of placebo, 10 g or 30 g of BNT162b1, or received a single dose of 100 g of the vaccine candidate.

According to the scientists, the highest neutralising concentrations of antibodies were observed seven days after the second dose of 10 g, or 30 g on day 28 after vaccination.

They said the neutralising concentrations were 1.8- and 2.8-times that observed in a panel of 38 blood samples from people who had contracted the virus.

In all 24 subjects who received two vaccinations at 10 g and 30 g dose levels, elevation of RBD-binding antibody concentrations was observed after the second injection, the study noted.

It said these concentrations are 8- and 46.3-times the concentration seen in a panel of 38 blood samples from those infected with the novel coronavirus.

At the 10 g or 30 g dose levels, the scientists said adverse reactions, including low grade fever, were more common after the second dose than the first dose.

According to Pfizer, local reactions and systemic events after injection with 10 g and 30 g of BNT162b1 were "dose-dependent, generally mild to moderate, and transient."

It said the most commonly reported local reaction was injection site pain, which was mild to moderate, except in one of 12 subjects who received a 100 g dose, which was severe.

The study noted that there was no serious adverse events reported by the patients.

Citing the limitations of the research, the scientists said the immunity generated in the participants in the form of the T cells and B cells of their immune system, and the level of immunity needed to protect one from COVID-19 are unknown.

With these preliminary data, along with additional data being generated, Pfizer noted in the statement that the two companies will determine a dose level, and select among multiple vaccine candidates to seek to progress to a large, global safety and efficacy trial, which may involve up to 30,000 healthy participants if regulatory approval to proceed is received.