Children who get less than the recommended 9-11 hours of sleep a night show signs of ageing faster at a cellular level, according to new research, underlining just how important it is for kids to be getting the right amount of shut-eye.
Researchers looked closely at the telomeres, the caps at the ends of chromosomes thought to signal cell ageing, and found telomere length averaged out at 1.5 percent shorter for each hour less that children slept a night.
The study of 1,567 kids, all 9 years of age, doesn't predict how this shorter telomere length might play out in later life, but the team from Princeton University told New Scientist that it "raises concerns" about how skipping sleep could hurt children's health as they grow up.
Short telomeres have in the past been linked to cancer, heart disease, and cognitive decline, and while these kids showed no signs of those major health problems, the researchers want to see long-term studies carried out to identify any links.
"This finding is consistent with a broader literature indicating that suboptimal sleep duration is a risk for increased physiological stress and impaired health," write the researchers.
No differences in telomere length were found based on the race, sex, or socioeconomic status of the kids.
Part of the role of telomeres is to protect our DNA code and to help cells divide – crucial in growing and repairing the body. These chromosome caps get shorter and shorter every time cells divide though, giving them a finite lifespan of usefulness.
When cells run out of telomeres they become inactive or die off, a process linked to ageing and various health problems – although we're still not sure if shortened telomeres are a cause of ageing or a sign of ageing (like grey hair).
Some special cells, including stem cells, can regenerate telomeres through an enzyme called telomerase, but broadly speaking you can think of telomeres like little biological clocks ticking down.
It's worth emphasising that this research didn't flag any scary medical issues in the children who slept less, but given the link between short telomeres and certain diseases, starting off life with a shorter supply is unlikely to be good news.
The researchers also note that some unmeasured factor may be affecting both sleep times and telomere length, and that sleep times were based on reports from mothers rather than direct measurements, so treat these as preliminary findings for now.
We'll have to wait for further studies to get a clearer picture, but until then you can teach your kids about telomeres the next time they complain about an early bedtime.
"Studying telomere length may be promising for understanding how health disparities are developed, maintained, or exacerbated over the life course," conclude the researchers.
The research has been published in The Journal of Pediatrics.