Does Going to Bed Too Late Cause Weight Gain?

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The importance of getting enough sleep cannot be overstated when it comes to your child’s health, development, and mood. Children who don’t get enough sleep are prone to irritability, difficulty concentrating at school, and reduced immunity. Now research shows regular sleep deprivation can lead to childhood obesity as well. 

A handful of recent studies have found an association between inadequate sleep and a sluggish metabolism—starting in children as young as 4 years old. Later bedtimes are also linked to an increased body mass index (BMI), excessive snacking, and higher levels of obesity. 

The amount of sleep each child needs is individual and based on age. Preschoolers will need more sleep than teenagers, who still need more sleep than adults. The American Academy of Pediatrics bases sleep recommendations by age as follows:

How Much Sleep Does Your Child Need?
Preschooler: 3 to 5 years old 10 to 13 hours (including naps)
Grade schoolers: 6 to 12 years old 9 to 12 hours
Teenagers: 13 to 18 years 8 to 10 hours
American Academy of Pediatrics

Sleep and Metabolism

Not getting enough sleep at night goes hand in hand with excessive weight gain, and research shows it starts in preschool. A 2015 study published in the journal Pediatric Obesity found that 4- and 5-year-old children who slept less than 9.5 hours a night had a greater likelihood of obesity than their peers who slept at least 10 hours a night. In addition, survey data showed preschoolers who regularly went to sleep after 9 p.m. or woke before 6:30 a.m. were more likely to have higher than average BMIs.

One reason for this may be that a lack of sleep has been shown to slow metabolism. A 2015 study in the journal Obesity measured resting metabolic rates in adults in a sleep lab study and found subjects who were only allowed to sleep 4 hours had lower resting metabolic rates in the morning, which researchers suggest is aimed at conserving energy. The good news is metabolism returned to normal after making up for lost sleep.

Late Bedtimes and Weight Gain

Further research shows teens and young adults who go to bed late on weeknights are more likely to gain weight. In a study of nearly 3,500 adolescents who were followed between 1994 and 2009 in the National Longitudinal Study of Adolescent Health, researchers looked at how bedtimes affected BMI.

Adolescents who kept later average bedtimes during the school week were more likely to see an increase in BMI over time. In addition, the researchers noted that consumption of fast food appears to play a role in the relationship between bedtimes and BMI.

Sleep Deprivation and Appetite

While research into the link between childhood sleep deprivation and obesity is still somewhat limited, a plethora of studies on sleep in adults suggests a chronic lack of sleep may lead to increased calorie consumption.

In a 2013 study published in the journal Sleep, 225 healthy young adults were randomly selected to spend either four or 10 hours in bed each night for five nights. Those in the sleep-restricted group consumed an additional 550 calories daily between the hours of 10 p.m. to 4 a.m. and gained an average of 2 pounds during the experiment.

A similarly designed study published in Sleep in 2016 linked this sleep-deprived appetite increase to changes in the endocannabinoid system, a key pathway involved in appetite and self-control. Sleep-restricted subjects were found to have altered levels of circulating endocannabinoids along with increased appetite and decreased willpower to resist palatable snacks.

Research also shows sleep impacts the hunger and satiety hormones leptin and ghrelin, which results in larger portion sizes and extra snacking when we don't get enough sleep.

How to Help Your Child Get More Sleep

Sleep researchers recommend putting young children to bed earlier in the evening to promote longer sleep duration to manage excessive weight gain. As any parent knows, however, that isn't always easy. Many kids—from preschool to high school—resist bedtime. The American Academy of Pediatrics offers these tips for encouraging better sleep habits:

Keep active during the day: Make sure your child gets a varied amount of activities including physical activities and fresh air. If your child's energy level seems to ramp up just before bedtime, try increasing physical activity an hour or so earlier in the evening to wear them out.

Be consistent: Keeping your child's day-to-day schedule largely the same, including when they eat, sleep, play, and wake, can help children feel secure and comfortable, which makes for easier bedtimes.

Set a bedtime routine: A calming bedtime ritual can help set the stage for falling asleep faster. Preparing for bed each night by following the same order of dressing for bed, brushing teeth, then reading a book or singing lullabies can help your child's body become ready for sleep. As your child grows through different stages, help them to develop new routines, such as washing their face, solitary reading, or meditating.

Turn off electronics: Blue light from screens can disrupt the body's natural sleep cycle. Avoiding screens for at least one hour before bed is recommended.

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  7. American Academy of Pediatrics: HealthyChildren.org. Healthy sleep habits: How many hours does your child need? Updated July 2, 2018.

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