By Sam Blanchard Senior Health Reporter For Mailonline
Published: 01:00 GMT, 9 January 2020 | Updated: 01:00 GMT, 9 January 2020
Doctors could tell whether a child is sleep-deprived simply by doing a blood test, according to scientists.
Children should get at least nine hours' sleep a night until they're 16 years old, and not getting enough could damage their health.
Too little sleep may stunt children's growth, make them less able to pay attention at school and up their odds of being overweight or diabetic.
It can be hard to tell how much sleep a child really gets because it depends on them, or their parents, remembering or telling the truth to a doctor.
Parents may not even have an accurate idea of how much sleep their child gets if they don't check on them during the night.
But scientists say they have now developed a blood test which can reveal the truth about a child's sleeping habits.
Children should get between 12 and nine hours sleep every night, depending on their age and declining steadily from the age of three, until they are 16, according to the NHS (stock image)
Researchers at the Institute of Food Sciences of the National Research Council in Italy created the test.
It works by picking up on molecules in the blood called microRNAs. MicroRNAs control which genes are most active in someone's body.
Scientists saw significant changes in the numbers of certain microRNAs, depending on how much sleep someone had had. It was not clear at what times the microRNAs were tested.
Looking at levels of two different microRNAs allowed them to differentiate between children who did or didn't sleep for nine hours a day.
For one microRNA, called miR-26b-3p, average levels were 15 per cent higher in the blood of children who did get