Studies suggest daytime napping may prevent children sleeping properly at night and impair mental performance.
Scientists in the US measured how well 27 kindergarten children could solve puzzles requiring planning and organisational skills. Children who took longer naps completed fewer puzzles successfully, and the later they went to bed the worse they performed, New Scientist magazine reported.
The team led by Dr Joe McNamara, from University of Florida, Gainesville, was one of a number of groups who presented similar findings at a meeting of the Associated Professional Sleep Societies in Minneapolis.
Dr John Harsh and colleagues from the University of Southern Mississippi found napping children found it more difficult to go to bed, slept badly and struggled to get up in the morning.
Dr Harsh said the findings posed a “chicken and egg” problem: “It could be that children are getting less sleep at night because they are napping, or they could be napping because they’re getting less sleep at night,” he said.
Dr McNamara said: “Napping is not a substitute for night-time sleep.”