Let your kids get more sleep, else they'll age faster.

Any parent knows the value of a nap when it comes to preventing crankiness. But why do kids need so much sleep? And what happens to them physically if they don't get it? A new study shows that lack of sleep can be harmful to kids on a cellular level, but don't worry. We've also dug up some science-backed solutions for when your kids aren't sleeping enough.

A lot of kids can't wait to grow up, but without a regular sleep schedule, they might get hit with all of the drawbacks of aging without any of the benefits. That's because, according to a new study published in The Journal of Pediatrics, a lack of sleep can cause cells to show some signs of early aging. Here's what happens:

Telomeres are little "tags" at the end of every chromosome, and they limit cellular division by shrinking every time a cell divides. Think of it like a fuse. When the fuse runs out, the cell dies. As the telomeres get too short, the cells can't divide anymore, and that cuts back on how well the body can repair and replenish itself. We call that process "aging."

But according to authors Sarah James and Daniel Notterham from Princeton University, a lack of sleep can cause telomeres to shrink as well. In a group of nearly 1,600 nine-year-old children, the researchers found that with every hour less of sleep, telomere length was on average 1.5 percent shorter. It's another way that early development health can have effects that last a lifetime.

Cellular damage isn't the only negative side effect of kids skipping sleepytime. Insomnia's impact on the brain is well documented in children and adults alike, and one study from 2016 suggested that children with sleep disorders are more likely to become adults with emotional disorders. So it's pretty important to let your kids get their recommended nightly shuteye—between 7 and 17 hours, depending on age.

It's one thing to know how important sleep is for growing kids, and something else entirely to actually convince a nine-year-old to go to bed. Fortunately, science has got your back on that front as well. In 2011, Jennifer Vriend and Penny Corkum from Dalhousie University released a study documenting exactly what works for what age group.

• For infants under 6 months, the key is parental education. Babies whose mothers had 45 minutes to talk about healthy sleep patterns with a nurse were shown to sleep longer and wake up less at night — and better yet, the mothers slept better as well.
• For older infants in the 6- to 12-month range, healthy sleep was easier to achieve when parents stopped reinforcing attention-seeking behavior. In other words, when mom and dad stopped going to check in on a crying baby, the baby got to sleep sooner. That can be tough, though, so the researchers suggested merely cutting back on check-ins could help as well.
• Toddlers and small children need to have good sleep hygiene reinforced. That means turning the lights out, keeping the room cool, and avoiding all glowing screens for a couple hours before bedtime.
• Older kids and tweens should be given the opportunity to judge their sleepiness for themselves. If they have serious issues falling asleep at a decent hour, though, parents might want to try setting a late bedtime that they can actually abide by, then gradually reeling it back 15 minutes at a time. The goal is that, by the time they're teenagers, most kids will just know the value of a good night's rest. If our teenage years were any indication, the real problem is going to be waking them up.

Curiosity.