Study: Significant association between obesity and ADHD

A recent study showed a significant association between obesity and ADHD in adults and children.

Results from a meta-analysis published in the American Journal of Psychiatry indicated a significant association between obesity and attention-deficit/hyperactivity disorder among children and adults.

“The putative association between ADHD and obesity might seem paradoxical because, rather than being hyperactive, individuals with obesity are often described as ‘lazy.’ However, the impulsivity and inattention that characterize ADHD might lead to dysregulated eating patterns with consequent weight gain,” Samuele Cortese, MD, PhD, of the University of Southampton, United Kingdom, and colleagues wrote. “The role of possible confounders, including low socioeconomic status and comorbid mental health conditions, in explaining the association between obesity and ADHD is still unclear. In addition, the role of age, gender, study setting, or study country is also uncertain.”

Researchers conducted a meta-analysis of 42 studies to assess the association between ADHD and obesity. The analysis included 728,136 study participants, of which 48,161 had ADHD.

Researchers found a significant association between obesity and ADHD among children (OR = 1.2; 95% CI, 1.05-1.37) and adults (OR = 1.55; 95% CI, 1.32-1.81).

Pooled prevalence of obesity increased by approximately 70% for adults with ADHD compared with those without ADHD, and by approximately 40% for children with ADHD vs. those without ADHD.

The significant association between obesity and ADHD remained when limited to studies that adjusted for potential confounding factors, diagnosed ADHD by direct interview and directly measured height and weight.

Researchers also found a significant association between ADHD and overweight.

Individuals medicated for ADHD did not have a higher risk for obesity.

“We found meta-analytic evidence of a significant association between obesity/overweight and ADHD, regardless of possible confounders. Mediational effects and causal mechanisms underlying the association, as well as the long-term effects of ADHD medications on weight status in individuals with obesity and ADHD, deserve further attention because of their important public health implications,” the researchers concluded.”

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Childhood sleep disorders could hurt a child's heath

When you think of sleep disorders in children, the first types likely to spring to mind are night terrors, nightmares and sleepwalking. These fall into a class of sleep disorders known as parasomnias.

It is estimated that up to 6.5% of children - particularly those aged 4-12 years - experience night terrors, defined as episodes of intense fear, screaming and flailing during sleep. Approximately 3% of preschool and school-aged children experience nightmares, while up to 15% of children aged 4-12 years sleepwalk.

Perhaps less associated with children and adolescents is insomnia and obstructive sleep apnea. In fact, insomnia, the inability to fall asleep or frequent awakening, is estimated to affect around 25% of children and teenagers. Obstructive sleep apnea - when an individual stops breathing for long periods during sleep - affects around 2-4% of children.

What are the causes and symptoms of childhood sleep disorders?

There are a number of factors that can cause childhood and adolescent sleep disorders.

Just like adults, children and teenagers can experience stress, which can interfere with sleep. Consumption of energy drinks - which contain caffeine - is also known to disrupt sleep, as is use of certain medications, such as antidepressants and corticosteroids.

Children and adolescents are also more likely to develop sleep disorders if they have a family history of such conditions, and poor sleep habits, or poor "sleep hygiene" - such as going to bed at irregular times or attempting to sleep in an inadequate environment - can negatively affect sleep quality.

Increasingly, researchers are pointing to the use of technology as a driver for sleep disorders. Last month,Medical News Today reported on a study published in BMJ Open that found children are 50% more likely to have problems getting to sleep if they spend 4 hours a day or more using media devices.

"In adolescents, with the increase in popularity of technology, many teens are staying up very late communicating with friends on smartphones and tablets. The stimulation and light exposure from these devices are associated with late bedtimes and insomnia," Dr. Neil Kline, a sleep physician and internist at the American Sleep Association, told MNT.

Although often harmless, snoring can be a major indicator for a sleep disorder in children and adolescents. It can be a sign of sleep apnea or disturbed sleep quality.

Other symptoms of sleep disorders to look out for include difficulty getting to sleep, daytime fatigue, poor memory, lack of concentration, reduced attention span, irritability and mood swings, hyperactivity and depression.

"If there is any concern for a sleep problem, such as a child taking longer than 20-30 minutes to fall asleep, not sleeping through the night after about age 1 year, or snoring, it is important to discuss this with the child's pediatrician, health care provider or a sleep doctor," Dr. Shalini Paruthi, a spokesperson for the American Academy of Sleep Medicine (AASM), told us.

Children and teenagers are not getting enough sleep

According to recently updated recommendations from the National Sleep Foundation (NSF), the number of hours sleep children and adolescents need is as follows:

Over the past 20 years, the number of hours teenagers sleep each night has fallen.

• Newborns (0-3 months): 14-17 hours a day
• Infants (4-11 months): 12-15 hours
• Toddlers (1-2 years): 11-14 hours
• Preschoolers (3-5 years): 10-13 hours
• School-age (6-13 years): 9-11 hours
• Teenagers (14-17 years): 8-10 hours.

However, it seems many children and teenagers are failing to meet sleep recommendations.

A 2014 poll from the NSF, which asked parents to estimate how much sleep their child gets on a school night, found that children aged 6-10 are only getting around 8.9 hours sleep a night, while 13-14-year-olds are only getting around 7.7 hours sleep each night.

More recently, MNT reported on a study published in the journal Pediatrics revealing that the number of hours teenagers sleep each night has declined over the past 20 years.

The study, which involved more than 270,000 adolescents, found that 72% of 15-year-olds were getting at least 7 hours or sleep each night in 1991, but this fell to only 63% in 2012.

"Declines in self-reported adolescent sleep across the last 20 years are concerning and suggest that there is potentially a significant public health concern that warrants health education and literacy approaches," said lead study author Dr. Katherine W. Keyes, of Columbia University's Mailman School of Public Health.

But why is lack of sleep among children and adolescents a public health concern?

Sleep deprivation linked to obesity, diabetes and heart problems

Sleep deprivation can cause a number of health problems for children and adolescents, both in childhood and adulthood.

In 2011, a study published in The BMJ claimed that children who do not get enough sleep are at significantly higher risk of becoming overweight, compared with children who get sufficient sleep.

Another study published in The Journal of Pediatrics in December 2014 reported a similar finding, associating severe lack of sleep and sleep-disordered breathing in early childhood with increased risk of obesity.

The researchers found that children with the shortest sleep time at the ages of 5 and 6 years were at 60-100% increased risk of obesity by the age of 15, compared with children with sufficient sleep times.

"If impaired sleep in childhood is conclusively shown to cause future obesity, it may be vital for parents and physicians to identify sleep problems early, so that corrective action can be taken and obesity prevented," commented lead study author Prof. Karen Bonuck, from the Albert Einstein College of Medicine of Yeshiva University in New York, NY.

In March last year, another study published in the same journal found that overweight adolescents who do not get enough sleep may be at increased risk of diabetes, heart disease and stroke.

Past studies have also associated sleep apnea in children with delayed growth and heart failure.

Lack of sleep 'makes it nearly impossible for children to reach their full potential'

It is widely accepted that sleep is important for learning and memory. In June 2014, MNT reported on a study that suggested as such. It found that sleep after learning boosts growth of connections between brain cells, helping them to communicate with each other.

A more recent study found that sleep is particularly important for infants' learning skills. Published in theProceedings of the National Academy of Sciences, the researchers revealed that infants aged 6-12 months who had at least one 30 minute nap within 4 hours of learning a new skill were much more likely to demonstrate the skills they learned once they awoke.

With findings such as these, it is no wonder that lack of sleep and poor sleep quality has been associated with poor learning and educational attainment among children and adolescents.

A 2013 study conducted by researchers from Boston College in the UK found that sleep deprivation was a major contributor to poor grades in numerous countries. While taking literacy tests, 76% of American 9-10-years-olds were identified as sleep-deprived, and these students were found to have poorer results.

"I think we underestimate the impact of sleep. Our data show that across countries internationally, on average, children who have more sleep achieve higher in maths, science and reading. That is exactly what our data show," study co-author Chad Minnich told BBC News.

Dr. Paruthi believes sufficient sleep is crucial for a child's overall health and development. She told MNT:

"Sleep disorders in children and teens can hinder them in school, in social situations, in development and nearly every other aspect of their lives, with the negative impact potentially extending into adulthood. Without healthy sleep, it will be nearly impossible for children to reach their full potential."

Parents should not assume children will 'grow out' of sleep disorders

It is possible that as a child or teenager gets older, symptoms of their sleep disorder may ease. This is most likely for parasomnias, such as sleepwalking and night terrors.

But in some cases, sleep disorders can persist well into adulthood. "For example, children who have sleep apnea are more likely to develop sleep apnea as adults," noted Dr. Kline.

As such, sleep physicians say parents should not ignore signs of sleep disorders in children with the assumption they will "grow out" of them.

"Parents should never assume that their child will grow out of a sleep disorder," Dr. Paruthi told us. "Parents should talk to their child's doctor about how their child sleeps and discuss any potential sleep problems. It is important for a doctor to monitor sleep problems during childhood, identify any underlying causes and prescribe appropriate treatment when necessary."

Depending on what form of sleep disorder a child has, there are a number of treatments available. Doctors may recommend a melatonin supplement, for example. Melatonin is a natural hormone made by the body that helps regulate sleep.

Cognitive behavioral therapy may also be useful, in which psychological approaches - rather than medication - are used to improve a child's sleep time and quality.

Tips to improve a child's sleep

But while there are a number of therapies that can help treat symptoms of sleep disorders, there are many things the NSF say parents can do to improve the likelihood of their child getting a good night's sleep:

The NSF say parents should ensure their child is sleeping in an adequate environment; if it is too noisy, too cold or too hot, this can disrupt sleep.

• Make sleep a primary health priority in your family
• Talk to your child about the importance of sleep for their health and well-being
• Set regular bedtimes for yourself and your children and stick to them
• Be aware of how your child is using media devices in the bedroom and set boundaries for use before bedtime
• Ensure you and your child are educated on how light from media devices may impair sleep
• Rather than watching TV, playing video games or browsing the Internet before bedtime, encourage your child to read a book or listen to music
• Ensure your child is sleeping in an adequate environment; if it is too noisy, too cold or too hot, this can disrupt sleep
• Talk to your child's teacher to find out about their alertness during the school day, and ask them to inform you if they fall asleep in lessons.

To find out more about how to improve your child's sleep, visit the NSF website. Our Knowledge Center articles provide more general information on specific sleep disorders, including obstructive sleep apneaand insomnia.

Young kids' sleep and obesity

Young kids not getting enough sleep could lead to obesity later in life.

Lack of sleep and sleep-related breathing problems appear to boost children's risk of obesity, a new study finds.

What isn't clear from the study, however, is whether the sleep issues actually cause obesity, or if something else might explain the association between sleep problems and obesity.

Researchers analyzed data from about 1,900 youngsters in England. The researchers had about 15 years of follow-up on the children. Those who got the least amount of sleep at ages 5 and 6 had between a 60 percent and 100 percent increased risk of being obese at age 15. (For children aged 5 or 6, fewer than 10.5 hours of sleep a night is considered too little, according to the researchers.)

Children who got too little sleep at other ages were not at increased risk for obesity, according to the study.

The researchers also found that one-quarter of the children were at increased risk of obesity due to sleep-related breathing problems such as snoring and sleep apnea. Those with the most severe sleep-related breathing problems were twice as likely to become obese by ages 7, 10 and 15.

The risk was slightly lower in children whose sleep-related breathing problems peaked at ages 5 or 6, but was still 60 percent to 80 percent higher than among those without sleep-related breathing problems.

The researchers didn't look at whether children with both these risk factors had a higher risk of obesity than those with just one of the risk factors.

"In recent years, lack of sleep has become a well-recognized risk for childhood obesity," study author Karen Bonuck, a professor of family and social medicine, and obstetrics, gynecology and women's health at Albert Einstein College of Medicine in New York City, said in a college news release.

"We know that the road to obesity often begins early in life. Our research strengthens the case that insufficient sleep and SDB (sleep-disordered breathing) -- especially when present early in childhood -- increase the risk for becoming obese later in childhood," she added.

"If impaired sleep in childhood is conclusively shown to cause future obesity, it may be vital for parents and physicians to identify sleep problems early, so that corrective action can be taken and obesity prevented. With childhood obesity hovering at 17 percent in the United States, we're hopeful that efforts to address both of these risk factors could have a tremendous public health impact," Bonuck concluded.

A common cause of sleep-related breathing problems in children is enlarged tonsils or adenoids. If these are a problem, they can be removed through surgery. Another possible cause is misalignment of the jaws and teeth. This problem can be treated with a night guard or orthodontics.

Learning good sleep habits can help children get adequate sleep, Bonuck said.

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Short sleep and breathing issues increases obesity risk in children

A child's risk of obesity is increased by sleeping for short amounts of time and breathing issues while sleeping.

Too little sleep has officially been linked to an increased risk of obesity, particularly among young children. Recent findings published in The Journal of Pediatrics reveals a high connection between sleep-related breathing problems and obesity.

For the study, researchers analyzed data from 1,900 children in England and followed the participants for about 15 years. Study results showed that those who got the least amount of sleep between the ages 5 and 6 had between a 60 percent and 100 percent increased risk of obesity by age 15.

"In recent years, lack of sleep has become a well-recognized risk for childhood obesity," said lead study author Karen Bonuck, Ph.D., professor of family and social medicine and of obstetrics & gynecology and women's health at Einstein, in a news release. "Sleep-disordered breathing, or SDB, which includes snoring and sleep apnea, is also a risk factor for obesity but receives less attention. These two risk factors had not been tracked together in children over time to determine their potential for independently influencing weight gain. Our study aimed to fill in that gap."

Furthermore, researchers found that children with the most severe sleep-disorder breathing (SDB) had the highest obesity risk. Children whose SDB levels peaked at around 5 to 6 years old still had a 60 to 80 percent increased risk of obesity, but fared better overall.

"If impaired sleep in childhood is conclusively shown to cause future obesity, it may be vital for parents and physicians to identify sleep problems early, so that corrective action can be taken and obesity prevented. With childhood obesity hovering at 17 percent in the United States, we're hopeful that efforts to address both of these risk factors could have a tremendous public health impact," Bonuck concluded.

A common cause of sleep-related breathing problems in children is oftentimes due to enlarged tonsils or adenoids, which can be removed with surgery if a problem occurs. Misalignment of jaws or teeth can also cause issues.

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Teens who sleep less gain more weight in 20s

A study shows that less sleep during the teen years means a person gains more weight by age 21.

Lack of sleep not only puts teens at risk for poor grades, it also puts them at increased risk for obesity, researchers warn.

The study authors analyzed data collected from more than 10,000 Americans when they were aged 16 and 21. Nearly one-fifth of them got less than six hours of sleep a night when they were age 16, and this group was 20 percent more likely to be obese at age 21 than those who got more than eight hours of sleep per night at age 16, the investigators found.

Although lack of exercise and too much time spent watching television were also risk factors for obesity, these behaviors did not account for the link between lack of sleep and obesity, according to the study published online recently in the Journal of Pediatrics.

"Lack of sleep in your teenage years can stack the deck against you for obesity later in life. Once you're an obese adult, it is much harder to lose weight and keep it off. And the longer you are obese, the greater your risk for health problems like heart disease, diabetes, and cancer," study author Shakira Suglia, an assistant professor of epidemiology at the Mailman School of Public Health at Columbia University in New York City, said in a university news release.

"The message for parents is to make sure their teenagers get more than eight hours a night. A good night's sleep does more than help them stay alert in school. It helps them grow into healthy adults," Suglia added.

Teens should get nine to 10 hours of sleep a night, according to the U.S. Centers for Disease Control and Prevention.

It's known that daytime sleepiness and fatigue affect what and how people eat by triggering cravings and altering appetite. For example, sleep-deprived people find it easier to buy calorie-laden fast food rather than preparing a healthy meal.

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Sleep deprivation and obesity in children

This article explains that sleep deprived children are more likely to be obese than children who get enough sleep.

Tired and hungry. There is a reason why these two conditions seem to go together so easily.

A “well established” link in medical research suggests young children and infants who do not get enough sleep are likely to develop obesity —and a host of devastating related health conditions — before they enter their teen years.

And by then, reversing the obesity is almost impossible, health experts say.

A study published in May in the journal “Pediatrics” hypothesizes that children sleeping less in early childhood developed obesity by age 7.

But the findings — from researchers at Massachusetts General Hospital for Children — are hardly shocking, say local physicians.

While studies such as this are likely to be confirmed by additional research in the years ahead, the other non-controversial conclusion is that obese children who suffer from obstructive sleep apnea also experience a variety of health issues, according to Dr. Ignacio Tapia, a pediatric pulmonologist and sleep medicine specialist at the Sleep Center in The Children’s Hospital of Philadelphia.

Tapia notes that youngsters of normal weight who experience deep sleep and REM or rapid eye movement sleep find sleep restorative, resulting in benefit for everything from brain activity to hormone secretions.

But the obese often cannot attain deep sleep because of the apnea, a condition characterized by brief, numerous involuntary breathing pauses that prevent people from reaching restorative levels of slumber.

When children do not get the sleep they need, they are at risk for health, performance and difficulties in school; researchers find that sleep deficiencies in children can be misdiagnosed as attention-deficit or behavior disorders.

Young patients with sleep apnea can be treated effectively with surgery to remove their tonsils and adnoids but for obese children, such a procedure may not resolve the issue. Further treatment can involve wearing cumbersome masks that help regulate breathing.

“Remember when your grandparents told you you need to go to sleep to grow?” Tapia asked. “Well, that turned out to be true. Growth is associated with longer sleep. The people who sleep less (for example) may have less insulin secretion which can be related to diabetes and pre-diabetes.”

Since the 1800s, each generation has lived longer than the one that preceded it, said Tapia, also assistant professor of Pediatrics at the Perelman School of Medicine at the University of Pennsylvania. Such longevity can be linked to the development of antibiotics and advances in cardiac care.

Now, this generation may be the one that loses ground, because of the epidemic of obesity, which is a complex issue relating to social and cultural issues as well and having income components, physicians say. Those who earn less may not have ready access to healthy foods while eating at fast-food chains has been made increasingly affordable, Tapia said. Portion size also is an issue in this country.

“We are seeing patients who are not a little big but really really big,” he said. “It is not rare to see patients who have doubled their ideal weight. They do not weigh 20 or 30 percent more but 100 percent more’’ than growth charts indicate.

The “Pediatrics” study measured the effect of sleep deficiencies over time, using data from Project Viva, a longitudinal research study of women and children that examines the effects of mothers’ diets and other factors during pregnancy and after birth.

Obesity “definitely spans all ages,” said Dr. Tina Rakitt, a pediatric gastroenterologist at the Unterberg Children’s Hospital at Monmouth Medical Center. But the study published in May “is unique enough to say the obesity and sleep link even exists in young children,” she added. “There are many reasons for that link. People who don’t sleep well tend to eat more and they tend to eat more of the wrong things.”

The battle is lost once children are old enough to select their own snacks or meals, unless they are taught correctly. Physicians say healthy eating must be established when children are infants and must be carried on by the family. Obesity does not exist in a vacuum, the experts said.

“The obesity epidemic is not only an adult problem; it is a adult-pediatric problem,” Rakitt said. “We are seeing more sleep apnea…That is a terrible one. Children are developing fatty liver disease. We are starting to see some kids with serious complications either in their childhood or young adult years.”

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Whole family needs to sleep to protect against childhood obesity

A study looked into familial sleeping patterns and found that parents and children must get enough sleep to protect against childhood obesity.

Is sleep one of your most important family values? A new University of Illinois study suggests that it should be, reporting that more parental sleep is related to more child sleep, which is related to decreased child obesity.

"Parents should make being well rested a family value and a priority. Sleep routines in a family affect all the members of the household, not just children; we know that parents won't get a good night's sleep unless and until their preschool children are sleeping," said Barbara H. Fiese, director of the U of I's Family Resiliency Center and Pampered Chef Endowed Chair.

And the effects of sleeplessness go beyond just being tired the next day. Studies show that moms, dads, and their children are likely to gain weight as they lose sleep, she said.

Fiese suggests limiting your children's exposure to TV and other electronic devices to two hours a day and turning them off a half-hour before bedtime (needless to say, children should not have televisions in their bedrooms); spending some time in a calming, predictable routine, such as giving the child a bath or reading together; and making sure preschoolers are in bed in time to get the recommended 10 hours of sleep a night.

Then adults should follow a calming routine themselves. "We're learning more and more about how important it is to unplug for a half-hour or so before we go to bed. At a certain time, turn off your electronic devices -- even e-books -- and engage in whatever soothing ritual helps you to relax enough to sleep," she said.

Although the mechanism hasn't yet been identified, Fiese said that restorative sleep is thought to help regulate our metabolism. Her recent study showed that sleep is a protective factor in lowering the incidence of obesity in parents and being overweight in preschool children.

In the study, socioeconomic characteristics were assessed in relation to protective routines and prevalence of being obese or overweight for 337 preschool children and their parents. The routines assessed in parents included adequate sleep (over seven hours) and family mealtime routine. The four protective routines assessed in children were adequate sleep (10 or more hours per night), family mealtime routine, limiting screen-viewing time to less than two hours a day, and not having a bedroom TV.

The only significant individual protective factor against obesity or overweight in children was getting adequate sleep. Children who did not get enough sleep had a greater risk for being overweight than children who engaged in at least three of the protective routines regularly, even after controlling for parents' BMI and socio-demographic characteristics, Fiese said.

But the researchers also learned that the number of hours a parent sleeps is related to how much sleep children are getting, so that a parent's sleep has an effect on the likelihood that their children will be overweight or obese.

"We viewed how long parents slept and how long children slept as part of a household routine and found that they really did go together," she said.

In an earlier study, Fiese followed families for a year and was surprised when parents reported that their five- to seven-year-old children were going to bed as late as 11 p.m. When she looked deeper into the reason for these late bedtimes, she found that parents who worked late into the evening viewed those late-night hours with their children as a special time.

"They described cuddling on the couch, watching television, and the child falling asleep in his parent's arms at 10 or 11 p.m. and being carried to bed. You can understand how it happens, but that's too late for a child who has to get up and go to school the next day," she noted.

She noted that inadequate sleep is not just a problem for preschoolers but for elementary school children and high school students whose brains are still developing. Adults don't function well on inadequate sleep either, she noted.

Fiese sees obesity intervention as a three-legged stool in which every member of the family is able to eat well, play well, and sleep well.

"Paying attention to those three pillars of health -- good nutrition, enough exercise, and adequate sleep -- benefits everyone in the family," she said.

"Parent routines, child routines, and family demographics associated with obesity in parents and preschool-aged children" was published in the April 2014 issue of Frontiers in Psychology. Blake L. Jones of Purdue University and Barbara H. Fiese and the STRONG Kids Team of the University of Illinois co-authored the article. The Illinois Council for Agriculture Research, the U of I Health and Wellness Initiative, and USDA funded the study.

Members of the U of I's Strong (Synergistic Theory and Research on Obesity and Nutrition Group) Kids research team include Kristen Harrison, now of the University of Michigan, and the U of I's Kelly Bost, Sharon Donovan, Brent McBride, Diana Grigsby-Toussaint, Angela Wiley, and Margarita Teran-Garcia.

The University of Illinois Family Resiliency Center is dedicated to advancing knowledge and practices that strengthen families' abilities to meet life's challenges and thrive.

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Sleep quality and obesity in children

A new study provides more evidence that sleep and sleep quality are linked to obesity in children.

Young children who get too little sleep are more likely than others to be obese by age 7, according to a new study.

Previous research has suggested insufficient sleep before age 4 raised the risk of obesity. But the new study, published online May 19 inPediatrics, observed the link from infancy to mid-childhood.

"Insufficient sleep is an independent and strong risk factor for childhood obesity and the accumulation of total fat and abdominal fat," said study researcher Dr. Elsie Taveras, chief of general pediatrics at Massachusetts General Hospital for Children in Boston.

"The main strength of this study is we looked at sleep at multiple periods," she added.

Excess body fat in childhood sets the stage for serious health problems, such as heart disease and diabetes.

Taveras and her team studied more than 1,000 children. Curtailed sleep was defined as fewer than 12 hours a day from ages 6 months to 2 years, fewer than 10 hours daily for ages 3 and 4, and fewer than nine hours a day for ages 5 to 7.

Kids who were most sleep deprived were about 2.5 times more likely to be obese than those who slept the most, the study found.

They were also 2.5 times more likely to have higher total fat, higher abdominal fat and a higher waist and hip circumference, said Taveras.

Many possible explanations exist for this association, Taveras said.

"If you sleep too little, it disrupts some of the hormones that regulate how hungry we are and how full we are," Taveras said.

In households with no consistent bedtime for children, there is likely to be chaos around regular mealtimes, too, and that can affect weight, she added.

Children who don't sleep enough may watch more television than kids who go to bed earlier, she said. Watching TV has long been linked with eating more, especially in response to food commercials, she said.

Or the children may have other "high-tech distractions," she said.

The new findings don't surprise Dr. William Muinos, director of the weight management program at Miami Children's Hospital in Florida, who was not involved in the study.

His advice for parents? Set a consistent bedtime. "Limit caffeinated beverages late in the day. Cut out all those electronic distractions; get them out of the bedroom," Taveras said.

Insist that children go to bed earlier, Muinos said. "Lack of sleep does change the physiology," he added. "It will put you in what is called stress mode. The body will read it as, 'I need to hold onto calories and accumulate fat.'"

The new research, Muinos said, "is very good because it studied a large group of children for a long period of time."

Ongoing studies are looking at whether improving sleep may directly improve weight control in children, Taveras said. And it's already known that good sleep has other benefits. "There's really good evidence that shows it improves schoolwork," she said.

For the study, mothers reported their children's usual sleep duration in a 24-hour period, beginning at age 6 months. They also reported it every year from age 1 to 7.

The children got a sleep score, ranging from zero (insufficient sleep) to 13 (consistent sufficient sleep). The average sleep score was 10.2. However, about 4 percent of kids were in the insufficient range, zero to 4. About 40 percent had a score of 12 or 13, termed enough sleep.

Those who slept less than average were more likely to be from poorer families with less educated mothers, the study found.

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Obesity and body fat in children are affected by chronic insufficient sleep

A study shows that chronic insufficient sleep can affect obesity and body fat in children.

One of the most comprehensive studies of the potential link between reduced sleep and childhood obesity finds compelling evidence that children who consistently received less than the recommended hours of sleep during infancy and early childhood had increases in both obesity and in adiposity or overall body fat at age 7. The study from MassGeneral Hospital for Children (MGHfC) investigators, published in the June issue of Pediatrics, also finds no evidence of a specific period during which insufficient sleep has greater influence on later obesity.

"Our study found convincing evidence that getting less than recommended amounts of sleep across early childhood is an independent and strong risk factor for obesity and adiposity," says Elsie Taveras, MD, MPH, chief of General Pediatrics at MGHfC and lead author of the Pediatrics paper. "Contrary to some published studies, we did not find a particular 'critical period' for the influence of sleep duration on weight gain. Instead, insufficient sleep at any time in early childhood had adverse effects."

While several studies have found evidence of an association between sleep and obesity in young children, few have examined the effects of constant sleep deprivation across time or used measures other than body mass index (BMI), which determines obesity based solely on height and weight. The current study analyzed data from Project Viva, a long-term investigation of the health impacts of several factors during pregnancy and after birth. Information used in this study was gathered from mothers at in-person interviews when their children were around 6 months, 3 years and 7 years old, and from questionnaires completed when the children were ages 1, 2, 4, 5 and 6.

Among other questions, the mothers were asked how much time their children slept, both at night and during daytime naps, during an average day. Measurements taken at the seven-year visit included not only height and weight but also total body fat, abdominal fat, lean body mass, and waist and hip circumferences -- measurements that may more accurately reflect cardio-metabolic health risks than BMI alone. Curtailed sleep was defined as less than 12 hours per day from ages 6 months to 2 years, less than 10 hours per day for ages 3 and 4, and less than 9 hours per day from age 5 to 7. Based on the mothers' reports at each age, individual children were assigned a sleep score covering the entire study period -- from 0, which represented the highest level of sleep curtailment, to 13, indicating no reports of insufficient sleep.

Overall, children with the lowest sleep scores had the highest levels of all body measurements reflecting obesity and adiposity, including abdominal fat which is considered to be particularly hazardous. The association was consistent at all ages, indicting there was no critical period for the interaction between sleep and weight. Lower sleep scores were more common in homes with lower incomes, less maternal education and among racial and ethnic minorities; but the association between sleep and obesity/adiposity was not changed by adjusting for those and other factors.

Facts and tips for healthy sleeping habits

While more research is needed to understand how sleep duration affects body composition, Taveras notes, potential mechanisms could include the influence of sleep on hormones that control hunger and satiety; the disruptions of circadian rhythms or possible common genetic pathways involved in both sleep and metabolism; poor ability to make good decisions on food choices and eating behaviors caused by sleep deprivation, or household routines that lead to both reduced sleep and increased food consumption. Insufficient sleep may also lead to increased opportunities to eat, especially if time is spent in sedentary activities, such as TV viewing, when snacking and exposure to ads for unhealthy foods are common.

"While we need more trials to determine if improving sleep leads to reduced obesity," she says, "right now we can recommend that clinicians teach young patients and their parents ways to get a better night's sleep -- including setting a consistent bedtime, limiting caffeinated beverages late in the day and cutting out high-tech distractions in the bedroom. All of these help promote good sleep habits, which also may boost alertness for school or work, improve mood and enhance the overall quality of life." Taveras is an associate professor of Pediatrics and Population Medicine at Harvard Medical School (HMS).

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