'He's my only son, so of course I was very worried,' Mrs Mazlina, now 34, said.

When Putera's breathing problems and snoring worsened, his parents took him to the National University Hospital (NUH).

He was diagnosed with obstructive sleep apnoea, a condition in which the nose and throat become blocked during sleep, causing breathing to stop temporarily.

About three per cent of children under seven here suffer from sleep apnoea, and that number appears to be on the rise. NUH paediatrician Chng Seo Yi said she saw 53 new cases last year.

Doctors are not sure why the numbers are on the rise. Some believe it could be driven by rising number of childhood asthma and obesity cases. They could also be a product of improved tests, which have led to more cases being caught.

Sleep apnoea in young children is usually caused by swollen tonsils or adenoids, whereas the majority of adult sleep apnoea cases are due to obesity. Children who are obese or have asthma are also at risk.

While not fatal, it prevents children from entering into deep sleep. If left untreated, the condition can lead to daytime drowsiness and behavioural problems in school.

To conclusively diagnose sleep apnoea, the child must undergo an overnight study that measures his breathing. For some, it is uncomfortable.

Fortunately, sleep apnoea is easily treated. Three-quarters of children recover after surgery to remove their tonsils or adenoids. The remaining 25 per cent have to don a mask-like respirator - called a continuous positive airway pressure device - while they sleep. They may have to wear it at night for the rest of their lives.

Now six, Putera has been using the machine for two years, his mother said he is snoring less.

Once overweight, he is now slimmer. 'He's actually getting much better,' said Mrs Mazlina.

caiwj@sph.com.sg