Ever witness a child struggle with school studies after a short night of sleep, get sick to their stomach from shoveling back Halloween candy or act lethargic after spending too much time parked on the couch? The immediate, short-term effects of not respecting the three pillars of health — a good night’s sleep, proper diet and ample physical activity — can be obvious.

Research also shows that in kids and adults, a lack of adequate rest can affect everything from mental health — associated with increases in impulsiveness and depressive symptoms — to our body’s ability to fend off the common cold. “Even in the short-term, sleep deprivation changes how we can fight off infection,” says Dr. Sally Ward, chief of pediatric pulmonology and sleep medicine at Children’s Hospital Los Angeles. It’s also easy enough to observe how being sedentary can lead to lower energy levels and eating poorly can undercut performance on physical and mentally challenging tasks.

What’s more difficult to fully appreciate is how kids’ healthy — or unhealthy — habits will affect them when they’re grown up — from their risk of disease to their expected lifespan. “Certainly we can link things like insulin resistance and Type 2 diabetes as well as elevated blood pressure and liver disease directly to obesity in children,” says Dr. Claudia Borzutzky, an adolescent medicine specialist who’s also board certified in obesity medicine and medical director of Empower Weight Management Clinic at CHLA. That’s not to say all kids who are overweight or obese will develop these issues as adults, or that those who aren’t overweight couldn’t; but excess weight can contribute to risk for these and other health conditions. “Kids who are overweight or obese are very, very likely to be overweight or obese as adults,” Borzutzky says, and she notes the longer a person carries excess weight, the greater the chances of developing weight-related problems.

[See: 8 Weird Ways Obesity Makes You Sick.]

Nor are such health issues relegated to adulthood. “We are seeing more kids who have … hypertension or high blood pressure as a result of their excess weight gain,” says Sonali Patel, a pediatric cardiologist at Children’s Hospital Colorado in Aurora, Colorado, who focuses on prevention. As is often the case, falling down on one pillar of health can topple another. Eating lots of junk food, especially late at night, can undermine sleep. Not getting enough sleep can make it harder to be active. “We know that poorer sleep increases your risk of having high blood pressure. We know poorer sleep increases your risk of having weight gain,” Patel says. “There’s a very clear association between our weight and sleep, and then all of the consequences that … stem from having excess weight — so things like high blood pressure and high cholesterol.”

Ultimately, experts say risk factors like obesity, a poor diet that’s low on fruits and veggies and other plant-based nutritonal powerhouses like nuts, and a lack of sleep in childhood can potentially affect a person’s long-term trajectory, and may even contribute to aging at a cellular level. One way to look at this is by evaluating the length of what are called telomeres, DNA-protein structures that form the ends of chromosomes in our cells. In most cells, telomeres become shorter as we age, shortening each time cells divide. However, habits ranging from smoking to getting inadequate sleep are also associated with shorter telomere length; and, though cause and effect has not been proven, studies have linked shorter telomeres with a higher risk for everything from heart disease and cancer to diabetes.

Studies of telomere length have focused mainly on adults. But recent research in the Journal of Pediatrics, first published online in June, found that in 9-year-old kids studied, getting less sleep was associated with having shorter telomeres compared with peers who got more sleep. “This finding is consistent with a broader literature indicating that suboptimal sleep duration is a risk for increased physiological stress and impaired health,” the researchers concluded. The American Academy of Pediatrics recommends kids ages 6 to 12 years get nine to 12 hours of sleep daily to promote optimal health.

[See: 8 Steps to Fall Asleep Fast.]

Though the association between shorter sleep duration and shorter telomeres had been established in adults, it hadn’t previously been studied in kids, says lead study author Sarah James, a Ph.D. student pursuing her doctorate in sociology and social policy at Princeton University, explaining the impetus for the study.

Senior study author Dr. Daniel Notterman, a pediatrician and professor of molecular biology at Princeton University, emphasized that a cause and effect relationship hasn’t been established between telomere length and later life health problems, like cardiovascular issues. But the researchers note, “Telomere length may be a particularly useful biomarker when assessing health in pediatric populations, because disparities in telomere length emerge before the manifestation of chronic health conditions in adulthood.”

To parents, experts say one thing is becoming increasingly clear: The good and the bad related to kids’ health today can have a profound impact on their tomorrow. So, for starters, it’s probably a good idea to help them rest easy. “Sleep is important, and sleep needs to be regular and routine,” Notterman says. He stresses consistency — there’s no making up for inadequate shuteye on the weekends — and having an established bedtime routine. That’s especially important when trying to get younger children ready for bed. Older kids — including teens — need to hear how getting to bed at a reasonable hour is crucial to their well-being, not to mention performance in the classroom and on the playing field, experts say — so they’ll be more likely to buy-in.

Similarly, parents need to teach kids why it’s also vital to eat right and exercise, and then to model healthy behaviors — something that can be much more difficult than talking about them. “Children will do what their parents do,” Borzutzky says.

[See: 10 Concerns Parents Have About Their Kids’ Health.]

But, if you face health struggles of your own, instead of writing yourself off as a bad example for your kids — or as a hypocrite for not having it all together — experts say use your experience to inform your efforts to set your child on the right path. “I think some of it is doing a little self-reflection,” Borzutzky says. “The parents of our patients who have weight problems often have weight problems themselves, or have some of those consequences related to their weight, such as high blood pressure, high cholesterol or diabetes or osteoarthritis of their knees.” She encourages them to consider, “‘If I could do things differently when I was growing up, what would that have been?'” It’s a question any parent might mull over before setting about to rewrite the script for their child.

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Are Late Nights, Little Exercise and a Lack of Veggies Aging Your Kids? originally appeared on usnews.com