Late nights and lax bedtime routines can blunt young children’s minds, research suggests.
The findings on sleep patterns and brain power come from a UK study of more than 11,000 seven-year-olds.
Erratic bedtimes were most common at the age of three, 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.
Youngsters who had no regular bedtime or who went to bed later than 21:00 had lower scores for reading and maths.
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.
The impact was more obvious throughout early childhood in girls than in boys and appeared to be cumulative.
The children with late and erratic bedtimes came from more socially disadvantaged backgrounds and were less likely to be read to each night and, generally, watched more TV – often on a set in their own bedroom.
Sleep experts point to a particular problem due to technology in children’s bedroom – specifically the use of screens on smartphones or laptops late at night.
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."
There was no evidence that putting children to bed much earlier than 19:30 added anything in terms of brain power.
Lack of sleep is a serious physical barrier to learning. Research into sleep disorders and brain function has shown the importance of sleep in memory and consolidating information. Without sleep, the brain struggles to absorb and retain ideas.