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Removing roadblocks to a good night’s sleep

SINGAPORE — Sleep comes easily for Ms Shi Li Qian, 51, who can fall asleep anywhere and at any time of the day. She nods off while waiting for public transport and during downtime at work.

An increasing number of women are seeking help for obstructive sleep apnoea, a sleep disorder that occurs when the upper airway is blocked during sleep. Photo: Reuters

An increasing number of women are seeking help for obstructive sleep apnoea, a sleep disorder that occurs when the upper airway is blocked during sleep. Photo: Reuters

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SINGAPORE — Sleep comes easily for Ms Shi Li Qian, 51, who can fall asleep anywhere and at any time of the day. She nods off while waiting for public transport and during downtime at work.

“I can even fall asleep while standing in the bus or MRT,” she said. Despite getting so much sleep throughout the day, she continues to feel exhausted and sleepy.

Five years ago, Ms Shi discovered the reason for her excessive daytime sleepiness: Obstructive sleep apnoea (OSA), a sleep disorder that occurs when the upper airway is blocked during sleep. This reduces blood oxygen saturation levels and disrupts sleep.

According to a 2012 community study, it is estimated that a third of Singaporeans suffer from OSA, with one in 10 having a severe form, said Dr Shaun Loh, an associate consultant at Singapore General Hospital (SGH)’s department of otolaryngology.

Ms Shi’s condition, which was diagnosed and treated at SGH, causes her to stop breathing in her sleep five to seven times every hour.

“The sleepiness isn’t so bad if I am in the midst of doing something or working. But the moment I relax, I fall asleep easily. My friends have also told me I snore very loudly in my sleep,” said Ms Shi, who is currently unemployed due to a joint problem.



An increasing number of women are seeking help for OSA, a sleep disorder once perceived to be a more of a men’s health issue.

The number of female patients seeking treatment for the condition has risen by 30 per cent between 2013 and 2017 at SGH, which saw more than 3,800 OSA cases last year. Women made up more than a quarter (27 per cent) of the 1,800 cases of new patients presenting with symptoms suggestive of OSA.

At ear, nose and throat surgeon Kenny Peter Pang’s practice, the number of women seeking help for the condition has approximately doubled in the past decade. The typical female OSA patient Dr Pang sees at Asia Sleep Centre, at Paragon Medical in Orchard Road, is aged between 30 and 50, whose husband is disturbed by her loud snoring at night.

She may be aware that she gasps for air and struggles to breathe at night and/or complains of some form of sinus problem as well as sleepiness in the day, he said.

Dr Pang has encountered women who stop breathing over 40 to 50 times per hour, which translates to over 300 times during a six-hour sleep per night.

Women at a higher risk of OSA include those who have undergone menopause or are pregnant.

Also at risk are women who are obese or have obstructions of the upper airway due to nasal allergies, large adenoids (the mass of soft tissue behind the nasal cavity) and tonsils, or certain facial structures such as a small, receding chin, which narrows the size of the upper airway, said Dr Loh.



While OSA is generally more common in men, studies have shown that the ratio of men to women diagnosed and treated is “extremely skewed”, with men eight to 10 times more likely to be seen at a clinic compared to women, said Dr Loh.

“However, studies have reported that the actual male-to-female ratio for OSA sufferers should lie between 3:1 to 5:1. So, why is it that men are almost 10 times more likely to be diagnosed with OSA when, in actual fact, they should only be three times more likely to have the disease?” he said.

Subtler symptoms may be a reason why OSA is under-detected in women. For example, women are less likely to report loud, chronic snoring, which is one of the classic signs of the disease, said Dr Loh.

“Instead, many report non-specific symptoms like chronic fatigue, insomnia, disrupted sleep with multiple awakenings, morning headaches, anxiety, depression and restless legs,” said Dr Loh. These symptoms are often not specific to a disease, and may be wrongly ascribed to other disorders like depression and lead to a prescription of antidepressants and sedatives rather than onward referral for a sleep study for evaluation, he added.

Differences in social behavior between the genders could play a part.

“Information from a partner on sleep disturbances may not be as readily available for women compared to men. Many male patients we encounter only seek treatment because their bed partners are concerned after witnessing their breathing disturbances,” said Dr Loh.

For patients with OSA, the frequent drops in oxygen levels during sleep means that they wake up unrefreshed and go on to feel sleepy in the day. In a sleep clinic’s waiting room, it is not unusual to find them fast asleep.

“These patients are unarousable when their names are called and the nurses often have to go tap them to wake them up,” said Dr Loh, who has encountered women who leave their jobs due to reasons such as an inability to stay awake and focus at meetings.

“These patients are often frustrated by the impact their fatigue has on work, social and family functioning,” he said.

Left untreated, OSA can be deadly. It is linked to a higher risk of hypertension, heart attacks and stroke, said Dr Pang.

Some studies suggest that women suffer worse consequences. For instance, a neuroimaging study published in the journal Sleep in 2012 showed that female OSA sufferers suffer more white-matter damage than their male counterparts – possibly why mood and cognitive symptoms linked to OSA may affect women more than men, said Dr Loh.

Another study found that women sufferers have more marked damage seen in the endothelium, the innermost lining of the blood vessels, he added.

In pregnant women, OSA has been linked to conditions like gestational diabetes and pregnancy-related hypertension, among others, according to a review article in Sleep Breath in 2014.



Depending on what’s contributing to the OSA and its severity, treatment will vary. Experts say it is important for people who suspect that they have OSA to consult a sleep specialist for proper diagnosis and assessment.

For OSA to be diagnosed, a sleep study is required. Patients sleep with a device that monitors various sleep and breathing indices for a night, said Dr Loh. This may be carried out overnight in the hospital or via a home-based wrist-worn device.

A continuous positive airway pressure (CPAP) machine, which Ms Shi is currently on, is one of the commonly prescribed treatments for OSA. The bedside machine helps her to breathe better at night by sending pressurised air through the nose and preventing the upper airway in the throat and behind the tongue from closing up.

“I still feel very tired the next day if I don’t use the CPAP at night but my quality of life has improved ever since I started using it,” said Ms Shi, who currently weighs around 130 kg and is also trying to lose weight to better manage her OSA.

Patients who are able to use CPAP will experience immediate improvement in their sleep and daytime functions, said Dr Loh.

“They will wake up feeling refreshed with improvement in daytime sleepiness and are able to concentrate better. Because they are sleeping well, their overall mood also improves,” he said.

For patients who are unable to accept or get used to CPAP therapy, other options exist. They include in-office procedures for mild cases, oral appliances worn at night as well as surgery, which can provide long-lasting results.

Some studies show that patients on surgery have better survival rates than those on the CPAP, said Dr Pang.

World Sleep Day falls on March 16 and the SGH is organising a Sleep For Health public forum on March 17 from 9am to 12pm at the auditorium of the Academia building. Registration is required and those interested may call 6326 6621 or email gnrsdu [at]

Hospital versus home: Which sleep test works better?

A sleep study to diagnose obstructive sleep apnoea can be done in either the hospital or at home. Each method has its pros and cons.

“Patients (who undergo an in-laboratory sleep study, or polysomnogram) usually feedback about the cost and they find it very uncomfortable with so many monitoring equipment and instruments on them, said Dr Toh Song Tar, head of SingHealth Duke-NUS Sleep Centre and Director of the Sleep Disorders Unit at SGH. This year alone, more than 700 patients have undergone the in-laboratory sleep study at SGH’s Sleep Disorders Unit. A polysomnogram costs S$708 at SGH (subsidised).

With an ambulatory home sleep study, which SGH also offers, patients wear a device on their wrists. They generally feel that their sleep is more natural as it is done at home, with fewer instruments and monitoring devices, said Dr Toh.

“Having said that, patients who are not used to having anything on their hands or on their body, still feel that their sleep quality is affected. Hence for us, it is important to ask the patients if the sleep they had for the test feels ‘normal’,” said Dr Toh.

The SGH currently uses the WatchPAT ambulatory home sleep study — which is scientifically validated and less costly than a polysomnogram — for those who cannot or do not want to come to the hospital for an in-laboratory sleep test.

Asia Sleep Centre’s Dr Kenny Peter Pang also offers it.

According to Dr Toh, there are some limitations with the WatchPAT test compared to an in-laboratory sleep study, which is more comprehensive and can diagnose the majority of sleep disorders.

For example, the WatchPAT test can only be used to determine if a patient has OSA and other sleep-related breathing disorders, but cannot be used to diagnose other sleep disorders, said Dr Toh.

“Also, it is not recommended for patients with significant heart or lung diseases. While published studies generally show good agreement between the in-laboratory polysomnogram (and) the WatchPAT study, the correlation is not 100 per cent. Patients who have a milder category of OSA may not be diagnosed accurately. A trained sleep specialist can interprete the results,” he said.

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