One in three Singaporeans suffers from moderate to severe obstructive sleep apnoea (OSA), with most of these cases undiagnosed, a recent study has found.
People with this sleep disorder stop breathing repeatedly in their sleep because of a complete or partial blocking in their airway.
This leads to low oxygen levels, which causes symptoms such as daytime fatigue, intellectual impairment and headaches upon waking.
The study by public healthcare group JurongHealth also found that one in 10 Singaporeans has severe sleep apnoea, in which they stop breathing for more than 30 times an hour during slumber.
The study, done between October 2014 and May last year among 250 randomly chosen subjects, was published in the international journal Respirology in March.
Its principal investigator, Dr Adeline Tan, described the high prevalence of the disorder among Singaporeans as worrying. About 90 per cent of the subjects found to have moderate to severe sleep apnoea were unaware of their condition.
Dr Tan, a consultant in respiratory medicine at Ng Teng Fong Hospital, said: "This could be due to low awareness of OSA. The public needs to know the signs so that they or their loved ones know when to seek medical help."
Signs include snoring, choking and gasping during sleep, and frequent urination at night.
Dr Kenny Pang, an ear, nose and throat specialist at Asia Sleep Centre and Mount Elizabeth Hospital, said he diagnoses 30 to 50 cases of sleep apnoea every month.
Patients' airways are blocked because of structural obstructions such as huge tonsils or tongues.
Dr Pang said there has been a huge leap in cases in the past decade, partly due to increased awareness of the condition.
"There is also an increased prevalence in obesity, a risk factor of the disorder," he noted, adding that over half of his sleep apnoea patients are obese or overweight. Those who are obese have more fat in the neck, which extends into their pharynx, or part of the throat, he explained.
Dr Tan's study also showed that Chinese and Malays here have higher rates of moderate to severe OSA, with their estimated population prevalence hitting 32.1 per cent and 33.8 per cent respectively.
Dr Pang said this is partly genetic.
"Asians in general have small jaws. When the face is narrow, the tongue has no space in the jaw and falls backwards during sleep, blocking the airway," he said.
Experts said that if left untreated, the condition could lead to hypertension, heart failure, poor job or academic performance and even an increased risk of traffic accidents.
There are three treatment options: surgery of the blocked air passage, wearing an oral appliance to pull out the lower jaw during sleep, or sleeping with a Continuous Positive Airway Pressure (CPAP) machine. This compresses atmospheric air and forces it into the airway through a facial or nasal mask.
Losing weight and avoiding smoking and alcohol help, said Dr Pang.
Sales manager Kenny Tang, 39, was diagnosed with sleep apnoea a year ago. "My wife and reservist bunk mates would say, 'You're not snoring, you're roaring.' "
He removed his left tonsil as it was so huge that it blocked half of his airway. His doctor also said he has a big tongue and small jaw.
Mr Tang, who is overweight, now sleeps with a CPAP machine. "I used to doze off when looking at my laptop in the office. Now I'm not so tired any more."