Rest Changes Through the Life Cycle
Rest is required for growth and maturation, but the requirements change over the life cycle. We need separate kinds of rest for special purposes at every stage of life – infancy, childhood, adolescence, and adulthood. Recent work points out some of what’s required for growing kids:
Infancy – Growing While You Sleep
Michelle Lample at Emory University was fascinated by the erratic behaviors of infancy. So she had mothers – and research assistants – track hour by hour activities of their infants over 7 months.
Sometimes the infants would experience very long sleeps – in girls during set intervals, in boys more throughout the 24 hour day. After they slept long they grew.
They got bigger. Longer. Heavier. Growth spurts occurred after sleep spurts.
Adults, please take note. It’s not just kids who grow in sleep – so do you. You rewire your brain, grow plenty of new skin (ever hear of beauty sleep?) and remake most of the rest of your body.
Partly this reshaping of body and brain is accomplished through growth hormone – which is produced mostly in deep sleep – stages 3 and 4 of sleep where your brain gets as close to coma as it normally attains. Through deep sleep decreases with age in both sexes, it can be increased by improving the continuity of sleep (all sleep disorders are a problem here – including insomnia) and by properly timed physical activity. That goes for growth hormone, too.
Children and Weight Gain
Rachel Taylor at the University of Otago (New Zealand) decided to follow a large group of 3 years old through their next 4 years. What she and her colleagues found was the less they slept, the higher their weight.
The effect was literally sizable. If children slept on average less than 11 hours over that period, they got bigger. For every hour of sleep average less than that, BMI went up by about .5.
The results simply reflect what also happens in adults – sleep less, weigh more. Yet children with their greater growth have greater rest and sleep needs than adults.
The mechanisms of why sleep loss leads to increased weight are probably innumerable. Some that have been identified are changes in energy metabolism; changes in the hormones glucose, ghrelin, and leptin, with even slight sleep deprivation; and changes in brain anatomy.
Adolescents and School Grades
Mary Carskadon has been a leader in sleep research for decades. She started pointing out in the 1970’s that sleep was required for better test scores and grades, and more recently has been leading the fight to make school start times later.
Recently highlighted by Jane Brody in the New York Times, that fight has gained some recent successes. Some schools, particularly in the region near Brown where Carskadon teaches, have started school later with excellent results – students with better moods and better grades.
In part that’s because the nature of rest in adolescents is very different from that of adults.
First, adolescents have thoroughly different body clocks. They go to bed and get up later than adults – generally becoming true night owls for their post-pubertal years.
Second, they require more sleep to function. Many researchers would argue 9-9.5 hours minimum is required so that adolescents will grow properly, be able to remember and learn (sleep is necessary for both), and be moderately alert in classes.
Except many adolescents and their parents don’t know teenagers need more rest – and adolescents don’t want to bother getting it.
There are more interesting things to do – text, sext, surf the Net, games, multitext – with an occasional phone call to the parents. Add on the demands for social popularity expressed via Facebook, and kids see hardly any point in wasting time on sleep.
Recent data shows many adolescents texting more than 100 times a day, and spending perhaps two hours texting per 24. Much of that texting occurs at night – interrupting sleep – which then fouls up growth hormone production and normal hormonal changes controlling weight.
So not only are adolescents tired, dour, sleepy and unawake through the first half of the school day – they also remember less, have lower grades, worse athletic and physical performance (yes, you need sleep for those things, too), and get heavier.
They don’t know that their future depends on rest.
Regenerating At Any Age
We change all the time. Our bodies regenerate in order to survive.
But as we develop into adults the changes brought by brain and body growth occur more quickly. To grow, to generate and regenerate, you need rest.
And kids – from infancy through adolescence, which in the brain may main the early twenties – need more rest than adults. Because they’re growing more, and regenerating themselves with greater rapidity.
We need to let the kids sleep. And they need us to tell them.
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