Late nights and lax bedtime routines can hamper young children's mental development according to a major study of more than 11,000 seven-year-olds.
Children who had no regular bedtime or who went to bed later than 9pm had lower scores for reading and maths. That led University College of London researchers to conclude that there was a significant correlation between lack of sleep and how well the brain learns new information.
Clear link between mental performance & lax bedtimes
Study lead Prof Amanda Sacker said that, even discounting for different family settings, the link between poorer mental performance and lax bedtimes was clear in the majority of children
"Often inconsistent bedtimes are a reflection of chaotic family settings and this can have an impact on cognitive performance in children," she explained However, even when we factored these [social] aspects into account, the link remained.
"The take-home message is really that routines really do seem to be important for children. Establishing a good bedtime routine early in childhood is probably best, but it's never too late."
Erractic bedtimes common at age three
Researchers gathered data on the children at the ages of three, five and then seven to find out how well they were doing with their learning and whether this might be related to their sleeping habits.
Erratic bedtimes were most common at three-years-old, when around one in five of the children went to bed at varying times.
By the age of seven, more than half the children had a regular bedtime of between 19:30 and 20:30.
Inter-related brain development factors
Overall, children who had never had regular bedtimes tended to fare worse than their peers in terms of test scores for reading, maths and spatial awareness.
Commenting on the findings, Dr Robert Scott-Jupp of the Royal College of Paediatrics and Child Health said: "At first glance, this research might seem to suggest that less sleep makes children less intelligent, however, it is clearly more complicated than that.
"While it's likely that social and biological brain development factors are inter-related in a complex way, in my opinion, for schoolchildren to perform their best, they should all, whatever their background, get a good night's sleep."