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Children who do not get enough sleep for one night can be cranky, groggy, or meltdown prone the next day.
Over time, though, insufficient sleep may impair neurodevelopment in ways that can be measured on brain scans and tests long term, a new study shows.
Research published in The Lancet Child & Adolescent Health found that 9- and 10-year-olds who do not get at least 9 hours of sleep most nights tend to have less gray matter and smaller areas of the brain responsible for attention, memory, and inhibition control, relative to children who do get enough sleep.
The researchers also found a relationship between insufficient sleep and disrupted connections between the basal ganglia and cortical regions of the brain. These disruptions appeared to be linked to depression, thought problems, and impairments in crystallized intelligence, a type of intelligence that depends on memory.
The overall patterns persisted 2 years later, even as those who got enough sleep at baseline gradually slept less over time, while those who were not getting enough sleep to begin with continued to sleep about the same amount, the researchers reported.
The results bolster the case for delaying school start times, as California recently did, according one researcher who was not involved in the study.
The ABCD Study
To examine how insufficient sleep affects children’s mental health, cognition, brain function, and brain structure over 2 years, Ze Wang, PhD, professor of diagnostic radiology and nuclear medicine at the University of Maryland, Baltimore, and colleagues analyzed data from the ongoing Adolescent Brain Cognitive Development (ABCD) Study. The ABCD Study is tracking the biologic and behavioral development of more than 11,000 children in the United States who were recruited for the study when they were 9 or 10 years old.
For their new analysis, Dr. Wang’s group focused on 6,042 participants: 3,021 children with insufficient sleep who were matched with an equal number of participants who were similar in many respects, including sex, socioeconomic status, and puberty status, except they got at least 9 hours of sleep. They also looked at outcomes 2 years later from 749 of the matched pairs who had results available.
The investigators determined sleep duration based on how parents answered the question: “How many hours of sleep does your child get on most nights in the past 6 months?” Possible answers included at least 9 hours, 8-9 hours, 7-8 hours, 5-7 hours, or less than 5 hours. They also looked at functional and structural MRI scans, test results, and responses to questionnaires.
Negative effects of inadequate sleep were spread over “several different domains including brain structure, function, cognition, behavior, and mental health,” Dr. Wang said.
The strength of the relationship between sleep duration and the various outcomes was “modest” and based on group averages, he said. So, a given child who does not sleep for 9 hours most nights won’t necessarily perform worse than a child who gets enough sleep.
Still, modest effects may accumulate and have lasting consequences, Dr. Wang said.
Crystallized intelligence
The researchers looked at 42 behavioral outcomes, 32 of which were significantly different between the groups. Four outcomes in particular – depression, thought problems, performance on a picture-vocabulary test, and crystallized intelligence – were areas where insufficient sleep seemed to have a larger negative effect.
Sleep duration’s relationship with crystallized intelligence was twice that for fluid intelligence, which does not depend on memory.
“Sleep affects memory,” Dr. Wang said. “Crystallized intelligence depends on learned skills and knowledge, which are memory. In this sense, sleep is related to crystallized intelligence.”
One limitation of the study is that some parents may not accurately report how much sleep their child gets, Dr. Wang acknowledged. Children may be awake when parents think they are asleep, for example.
And although the results show getting 9 hours of sleep may help neurocognitive development, it’s also possible that excessive amounts of sleep could be problematic, the study authors wrote.
Further experiments are needed to prove that insufficient sleep – and not some other, unaccounted for factor – causes the observed impairments in neurodevelopment.
To promote healthy sleep, parents should keep a strict routine for their children, such as a regular bedtime and no electronic devices in the bedroom, Dr. Wang suggested. More physical activity during the day also should help.
If children have high levels of stress and depression, “finding the source is critical,” he said. Likewise, clinicians should consider how mental health can affect their patients’ sleep.
More to healthy sleep than duration
“This study both aligns with and advances existing research on the importance of sufficient sleep for child well-being,” said Ariel A. Williamson, PhD, DBSM, a psychologist and pediatric sleep expert in the department of child and adolescent psychiatry and behavioral sciences at Children’s Hospital of Philadelphia and assistant professor of psychiatry and pediatrics at University of Pennsylvania, also in Philadelphia.
The researchers used rigorous propensity score matching, longitudinal data, and brain imaging, which are “innovative methods that provide more evidence on potential mechanisms linking insufficient sleep and child outcomes,” said Dr. Williamson, who was not involved in the study.
While the investigators focused on sleep duration, child sleep health is multidimensional and includes other elements like timing and perception of sleep quality, Dr. Williamson noted. “For example, some research shows that having a sleep schedule that varies night to night is linked to poor child outcomes.”
Dr. Williamson tells families and clinicians that “sleep is a pillar of health,” equal to diet and exercise. That said, sleep recommendations need to fit within a family’s life – taking into account after school activities and late-night homework sessions. But extending sleep by just “20-30 minutes can make a meaningful difference for daytime functioning,” Dr. Williamson said.
Start school later?
Researchers have only relatively recently begun to understand how insufficient sleep affects adolescent neurocognitive development long term, and this study provides “crucial evidence” about the consequences, Lydia Gabriela Speyer, PhD, said in an editorial published with the study. Dr. Speyer is affiliated with the department of psychology at the University of Cambridge (England).
“Given the novel finding that insufficient sleep is associated with changes in brain structure and connectivity that are long-lasting, early intervention is crucial because such neural changes are probably not reversible and might consequently affect adolescents’ development into adulthood,” Dr. Speyer wrote.
Delaying school start times could be one way to help kids get more sleep. The American Academy of Pediatrics and the American Academy of Sleep Medicine recommend that middle schools and high schools start no earlier than 8:30 a.m. to better align with students’ circadian rhythm, Dr. Speyer noted.
As it is in the United States, most schools start closer to 8 a.m. In California, though, a law that went into effect on July 1 prohibits high schools from starting before 8:30 a.m. Other states are weighing similar legislation.
The research was supported by the National Institutes of Health. Dr. Wang and his coauthors and Dr. Speyer had no conflict of interest disclosures. Dr. Williamson is a sleep expert for the Pediatric Sleep Council (www.babysleep.com), which provides free information about early childhood sleep, but she does not receive compensation for this role.
Children who do not get enough sleep for one night can be cranky, groggy, or meltdown prone the next day.
Over time, though, insufficient sleep may impair neurodevelopment in ways that can be measured on brain scans and tests long term, a new study shows.
Research published in The Lancet Child & Adolescent Health found that 9- and 10-year-olds who do not get at least 9 hours of sleep most nights tend to have less gray matter and smaller areas of the brain responsible for attention, memory, and inhibition control, relative to children who do get enough sleep.
The researchers also found a relationship between insufficient sleep and disrupted connections between the basal ganglia and cortical regions of the brain. These disruptions appeared to be linked to depression, thought problems, and impairments in crystallized intelligence, a type of intelligence that depends on memory.
The overall patterns persisted 2 years later, even as those who got enough sleep at baseline gradually slept less over time, while those who were not getting enough sleep to begin with continued to sleep about the same amount, the researchers reported.
The results bolster the case for delaying school start times, as California recently did, according one researcher who was not involved in the study.
The ABCD Study
To examine how insufficient sleep affects children’s mental health, cognition, brain function, and brain structure over 2 years, Ze Wang, PhD, professor of diagnostic radiology and nuclear medicine at the University of Maryland, Baltimore, and colleagues analyzed data from the ongoing Adolescent Brain Cognitive Development (ABCD) Study. The ABCD Study is tracking the biologic and behavioral development of more than 11,000 children in the United States who were recruited for the study when they were 9 or 10 years old.
For their new analysis, Dr. Wang’s group focused on 6,042 participants: 3,021 children with insufficient sleep who were matched with an equal number of participants who were similar in many respects, including sex, socioeconomic status, and puberty status, except they got at least 9 hours of sleep. They also looked at outcomes 2 years later from 749 of the matched pairs who had results available.
The investigators determined sleep duration based on how parents answered the question: “How many hours of sleep does your child get on most nights in the past 6 months?” Possible answers included at least 9 hours, 8-9 hours, 7-8 hours, 5-7 hours, or less than 5 hours. They also looked at functional and structural MRI scans, test results, and responses to questionnaires.
Negative effects of inadequate sleep were spread over “several different domains including brain structure, function, cognition, behavior, and mental health,” Dr. Wang said.
The strength of the relationship between sleep duration and the various outcomes was “modest” and based on group averages, he said. So, a given child who does not sleep for 9 hours most nights won’t necessarily perform worse than a child who gets enough sleep.
Still, modest effects may accumulate and have lasting consequences, Dr. Wang said.
Crystallized intelligence
The researchers looked at 42 behavioral outcomes, 32 of which were significantly different between the groups. Four outcomes in particular – depression, thought problems, performance on a picture-vocabulary test, and crystallized intelligence – were areas where insufficient sleep seemed to have a larger negative effect.
Sleep duration’s relationship with crystallized intelligence was twice that for fluid intelligence, which does not depend on memory.
“Sleep affects memory,” Dr. Wang said. “Crystallized intelligence depends on learned skills and knowledge, which are memory. In this sense, sleep is related to crystallized intelligence.”
One limitation of the study is that some parents may not accurately report how much sleep their child gets, Dr. Wang acknowledged. Children may be awake when parents think they are asleep, for example.
And although the results show getting 9 hours of sleep may help neurocognitive development, it’s also possible that excessive amounts of sleep could be problematic, the study authors wrote.
Further experiments are needed to prove that insufficient sleep – and not some other, unaccounted for factor – causes the observed impairments in neurodevelopment.
To promote healthy sleep, parents should keep a strict routine for their children, such as a regular bedtime and no electronic devices in the bedroom, Dr. Wang suggested. More physical activity during the day also should help.
If children have high levels of stress and depression, “finding the source is critical,” he said. Likewise, clinicians should consider how mental health can affect their patients’ sleep.
More to healthy sleep than duration
“This study both aligns with and advances existing research on the importance of sufficient sleep for child well-being,” said Ariel A. Williamson, PhD, DBSM, a psychologist and pediatric sleep expert in the department of child and adolescent psychiatry and behavioral sciences at Children’s Hospital of Philadelphia and assistant professor of psychiatry and pediatrics at University of Pennsylvania, also in Philadelphia.
The researchers used rigorous propensity score matching, longitudinal data, and brain imaging, which are “innovative methods that provide more evidence on potential mechanisms linking insufficient sleep and child outcomes,” said Dr. Williamson, who was not involved in the study.
While the investigators focused on sleep duration, child sleep health is multidimensional and includes other elements like timing and perception of sleep quality, Dr. Williamson noted. “For example, some research shows that having a sleep schedule that varies night to night is linked to poor child outcomes.”
Dr. Williamson tells families and clinicians that “sleep is a pillar of health,” equal to diet and exercise. That said, sleep recommendations need to fit within a family’s life – taking into account after school activities and late-night homework sessions. But extending sleep by just “20-30 minutes can make a meaningful difference for daytime functioning,” Dr. Williamson said.
Start school later?
Researchers have only relatively recently begun to understand how insufficient sleep affects adolescent neurocognitive development long term, and this study provides “crucial evidence” about the consequences, Lydia Gabriela Speyer, PhD, said in an editorial published with the study. Dr. Speyer is affiliated with the department of psychology at the University of Cambridge (England).
“Given the novel finding that insufficient sleep is associated with changes in brain structure and connectivity that are long-lasting, early intervention is crucial because such neural changes are probably not reversible and might consequently affect adolescents’ development into adulthood,” Dr. Speyer wrote.
Delaying school start times could be one way to help kids get more sleep. The American Academy of Pediatrics and the American Academy of Sleep Medicine recommend that middle schools and high schools start no earlier than 8:30 a.m. to better align with students’ circadian rhythm, Dr. Speyer noted.
As it is in the United States, most schools start closer to 8 a.m. In California, though, a law that went into effect on July 1 prohibits high schools from starting before 8:30 a.m. Other states are weighing similar legislation.
The research was supported by the National Institutes of Health. Dr. Wang and his coauthors and Dr. Speyer had no conflict of interest disclosures. Dr. Williamson is a sleep expert for the Pediatric Sleep Council (www.babysleep.com), which provides free information about early childhood sleep, but she does not receive compensation for this role.
Children who do not get enough sleep for one night can be cranky, groggy, or meltdown prone the next day.
Over time, though, insufficient sleep may impair neurodevelopment in ways that can be measured on brain scans and tests long term, a new study shows.
Research published in The Lancet Child & Adolescent Health found that 9- and 10-year-olds who do not get at least 9 hours of sleep most nights tend to have less gray matter and smaller areas of the brain responsible for attention, memory, and inhibition control, relative to children who do get enough sleep.
The researchers also found a relationship between insufficient sleep and disrupted connections between the basal ganglia and cortical regions of the brain. These disruptions appeared to be linked to depression, thought problems, and impairments in crystallized intelligence, a type of intelligence that depends on memory.
The overall patterns persisted 2 years later, even as those who got enough sleep at baseline gradually slept less over time, while those who were not getting enough sleep to begin with continued to sleep about the same amount, the researchers reported.
The results bolster the case for delaying school start times, as California recently did, according one researcher who was not involved in the study.
The ABCD Study
To examine how insufficient sleep affects children’s mental health, cognition, brain function, and brain structure over 2 years, Ze Wang, PhD, professor of diagnostic radiology and nuclear medicine at the University of Maryland, Baltimore, and colleagues analyzed data from the ongoing Adolescent Brain Cognitive Development (ABCD) Study. The ABCD Study is tracking the biologic and behavioral development of more than 11,000 children in the United States who were recruited for the study when they were 9 or 10 years old.
For their new analysis, Dr. Wang’s group focused on 6,042 participants: 3,021 children with insufficient sleep who were matched with an equal number of participants who were similar in many respects, including sex, socioeconomic status, and puberty status, except they got at least 9 hours of sleep. They also looked at outcomes 2 years later from 749 of the matched pairs who had results available.
The investigators determined sleep duration based on how parents answered the question: “How many hours of sleep does your child get on most nights in the past 6 months?” Possible answers included at least 9 hours, 8-9 hours, 7-8 hours, 5-7 hours, or less than 5 hours. They also looked at functional and structural MRI scans, test results, and responses to questionnaires.
Negative effects of inadequate sleep were spread over “several different domains including brain structure, function, cognition, behavior, and mental health,” Dr. Wang said.
The strength of the relationship between sleep duration and the various outcomes was “modest” and based on group averages, he said. So, a given child who does not sleep for 9 hours most nights won’t necessarily perform worse than a child who gets enough sleep.
Still, modest effects may accumulate and have lasting consequences, Dr. Wang said.
Crystallized intelligence
The researchers looked at 42 behavioral outcomes, 32 of which were significantly different between the groups. Four outcomes in particular – depression, thought problems, performance on a picture-vocabulary test, and crystallized intelligence – were areas where insufficient sleep seemed to have a larger negative effect.
Sleep duration’s relationship with crystallized intelligence was twice that for fluid intelligence, which does not depend on memory.
“Sleep affects memory,” Dr. Wang said. “Crystallized intelligence depends on learned skills and knowledge, which are memory. In this sense, sleep is related to crystallized intelligence.”
One limitation of the study is that some parents may not accurately report how much sleep their child gets, Dr. Wang acknowledged. Children may be awake when parents think they are asleep, for example.
And although the results show getting 9 hours of sleep may help neurocognitive development, it’s also possible that excessive amounts of sleep could be problematic, the study authors wrote.
Further experiments are needed to prove that insufficient sleep – and not some other, unaccounted for factor – causes the observed impairments in neurodevelopment.
To promote healthy sleep, parents should keep a strict routine for their children, such as a regular bedtime and no electronic devices in the bedroom, Dr. Wang suggested. More physical activity during the day also should help.
If children have high levels of stress and depression, “finding the source is critical,” he said. Likewise, clinicians should consider how mental health can affect their patients’ sleep.
More to healthy sleep than duration
“This study both aligns with and advances existing research on the importance of sufficient sleep for child well-being,” said Ariel A. Williamson, PhD, DBSM, a psychologist and pediatric sleep expert in the department of child and adolescent psychiatry and behavioral sciences at Children’s Hospital of Philadelphia and assistant professor of psychiatry and pediatrics at University of Pennsylvania, also in Philadelphia.
The researchers used rigorous propensity score matching, longitudinal data, and brain imaging, which are “innovative methods that provide more evidence on potential mechanisms linking insufficient sleep and child outcomes,” said Dr. Williamson, who was not involved in the study.
While the investigators focused on sleep duration, child sleep health is multidimensional and includes other elements like timing and perception of sleep quality, Dr. Williamson noted. “For example, some research shows that having a sleep schedule that varies night to night is linked to poor child outcomes.”
Dr. Williamson tells families and clinicians that “sleep is a pillar of health,” equal to diet and exercise. That said, sleep recommendations need to fit within a family’s life – taking into account after school activities and late-night homework sessions. But extending sleep by just “20-30 minutes can make a meaningful difference for daytime functioning,” Dr. Williamson said.
Start school later?
Researchers have only relatively recently begun to understand how insufficient sleep affects adolescent neurocognitive development long term, and this study provides “crucial evidence” about the consequences, Lydia Gabriela Speyer, PhD, said in an editorial published with the study. Dr. Speyer is affiliated with the department of psychology at the University of Cambridge (England).
“Given the novel finding that insufficient sleep is associated with changes in brain structure and connectivity that are long-lasting, early intervention is crucial because such neural changes are probably not reversible and might consequently affect adolescents’ development into adulthood,” Dr. Speyer wrote.
Delaying school start times could be one way to help kids get more sleep. The American Academy of Pediatrics and the American Academy of Sleep Medicine recommend that middle schools and high schools start no earlier than 8:30 a.m. to better align with students’ circadian rhythm, Dr. Speyer noted.
As it is in the United States, most schools start closer to 8 a.m. In California, though, a law that went into effect on July 1 prohibits high schools from starting before 8:30 a.m. Other states are weighing similar legislation.
The research was supported by the National Institutes of Health. Dr. Wang and his coauthors and Dr. Speyer had no conflict of interest disclosures. Dr. Williamson is a sleep expert for the Pediatric Sleep Council (www.babysleep.com), which provides free information about early childhood sleep, but she does not receive compensation for this role.
FROM THE LANCET CHILD & ADOLESCENT HEALTH