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.

Youngsters who had no regular bedtime or who went to bed later than 21:00 had lower scores for reading and maths.

Lack of sleep may disrupt natural body rhythms and impair how well the brain learns new information say the study authors.

The 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.

Establishing a good bedtime routine early in childhood is probably best, but it's never too late," they note.