(New Scientist) — A lack of sleep doesn’t just turn children into a grumpy handful, it may also accelerate their cellular ageing – a process that could have long-term health effects.

Telomeres – the caps at the ends of our chromosomes – get shorter every time our cells divide, and when they get too short, it is thought that cells are no longer able to divide to repair and replenish the body – a sign of ageing. Some small studies in adults have suggested that sleep might be linked to telomere length.

To find out if it is also the case in children, Sarah James and Daniel Notterman at Princeton University and their team dug into a database. It included information on average sleep duration collected from 1567 9-year-old children from cities across the US. The team extracted DNA from saliva samples from the children, and examined the length of their telomeres.

They found that telomeres were shorter in children who slept less (The Journal of Pediatrics, doi.org/b87r). “Telomere length is 1.5 per cent shorter for each hour less that children sleep per night,” says James.