It's after 10pm on a weekday, but the playgrounds can still be packed with young children at play.

They should be in bed by then, say doctors, who warn that insufficient sleep could affect the children's long-term health and academic abilities.

A study of 372 children aged from two to six by six paediatricians from the National University Hospital found that their snooze time is less than that of children in Switzerland, which has also done a study of the sleep patterns of children aged two and older.
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Two-year-olds here sleep about 11.3 hours a day, including naps - almost two hours less than the sleep time logged by Swiss children of that age. The toddlers had only nine hours of night-time sleep - 2.4 hours less than what Swiss children had.

Six-year-olds here had 8.8 hours of night-time sleep and about 10.4 hours including naps. The researchers did not give the length of time that Swiss children of that age slept, though they said they had more sleep at all ages.

The findings were published in the latest edition of the Annals, the journal of the Academy of Medicine, which is a society of medical specialists.

The paediatricians said there is no evidence that taking naps in the day is as good as uninterrupted sleep at night.

They were surprised with the large number of children over the age of two who were still taking naps in the daytime - more than 76 per cent, compared with just 5 per cent among Swiss children.

They said that is likely to be a 'reflection of inadequate night-time sleep', though they conceded that it could be due to cultural differences and schooling practices here.

The study found 44 per cent of children here had difficulty waking up in the morning and 40 per cent woke up tired - both symptoms of inadequate sleep.

The paediatricians said their findings were a 'cause for concern' since children with later or irregular bedtimes, short sleeping times and daytime sleepiness have 'lower academic achievements'.

They added: 'Sleep deprivations are associated with the increased incidence of learning disorders, unintentional injuries, obesity, impaired immunity and mood and anxiety disorders.'

What they found equally worrying is that a vast majority of parents think their children are sleeping enough.

About 84 per cent of parents said their children had enough sleep, 90 per cent said they had no sleep problems and even the 10 per cent who said there were problems felt the child would grow out of it.

The authors said there is a need to educate parents on the amount of sleep their children require.

One of them, Associate Professor Stacey Tay, told The Straits Times: 'My personal experience is that many children and teenagers are quite sleep-deprived. They see me in the clinic for headaches, dizziness and poor attention in class.'

But once they started sleeping longer, many of their physical problems improved, she said, adding that some children showed 'markedly improved academic ability'.

The study also noted that four in five children share the same room or bed with another person. This could lead to disruptions in sleep, even if the child gets the required number of hours.

The authors said: 'Both quantity and quality of sleep are important for the normal developmental growth of children.'

They concluded: 'The significantly shorter duration of sleep that Singaporean preschoolers obtain may have implications on their long-term health and academic performance.'

http://www.straitstimes.com/STI/STIMEDIA/pdf/20120419/ST_IMAGES_SKKIDS_LAST.pdf