Scientists at University College London investigating the effects of bedtime routine on child development asked children to complete a number of tests including basic number skills, reading out word cards, and constructing designs from flat or solid shapes. Although the hour that children went to bed had little or no effect on their performance, having no set bedtime often led to lower scores. The effect was most striking in three-year-olds, where boys and girls scored lower on reading, maths and spatial skills tests than children of the same age who kept to a more rigid schedule.