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Sleep apnoea: a common condition that often goes undiagnosed

Plain information for patients in Singapore about obstructive sleep apnoea: what it is, the signs to look out for, how a sleep study diagnoses it, and why it is worth finding out.

Medically reviewed by Dr Lim Jia Yang, Family Physician and Primary Eye Care Physician, MBBS (Singapore), DRCOphth (UK), MRCOphth (UK), GDFM (Singapore). Last reviewed 13 October 2026.

What sleep apnoea is

In obstructive sleep apnoea, the airway at the back of the throat narrows or closes again and again during sleep. Each time, breathing becomes shallow or stops for a few seconds, the oxygen level in the blood drops, and the brain briefly wakes the body up to reopen the airway. This can happen many times an hour, usually without the person remembering it.^[1]

The result is sleep that is broken into pieces, even when it seems to last all night. That is why people with sleep apnoea often wake up unrefreshed however long they sleep.

Signs to look out for

Night-time signs, often noticed by someone else first:^[2]

• Loud, regular snoring
• Pauses in breathing noticed by a bed partner^[1], or sudden gasping or choking during sleep
• Restless sleep, and getting up often to pass urine at night

Daytime signs:

• Feeling sleepy or tired during the day, or nodding off when sitting quietly
• Morning headaches, and a dry mouth or sore throat on waking
• Poor concentration or memory

Not everyone who snores has sleep apnoea, and not everyone with sleep apnoea snores loudly. The only way to know is a sleep study.

Who is more likely to have it

• Being overweight, which is one of the strongest risk factors.^[1][2]
• Face and jaw shape. A smaller jaw or a set-back chin leaves less room for the airway. This matters in Asia: studies have found that Chinese patients with sleep apnoea tend to have more of this bony narrowing than Caucasian patients, so sleep apnoea is not only a condition of people who are heavy.^[3]
• Being male. Men are affected more often than women, although women are affected too.^[4]
• Large tonsils, alcohol in the evening, and sleeping pills, which relax the throat muscles further.^[2]

Why it so often goes undiagnosed

Sleep apnoea is common, and most people who have it do not know. In a community study of adults aged 21 to 79 in Singapore who had a sleep test at home, 30.5% had moderate to severe sleep-disordered breathing, and 91% of them had never been diagnosed.^[5] An older study of middle-aged adults in the United States found much the same: 82% of men and 93% of women with moderate to severe sleep apnoea had not been diagnosed.^[6]

There are understandable reasons for this. It happens while you are asleep. Snoring is often treated as a joke or a nuisance rather than a symptom. And tiredness, poor concentration and low mood creep up slowly, so they get put down to work, stress or age. Many people live with it for years before anyone suggests a sleep test.

How a sleep study diagnoses it

Sleep apnoea is diagnosed with a sleep study, which records your breathing and oxygen levels while you sleep. Questionnaires about snoring and sleepiness can show who is more likely to have it, but they cannot diagnose it on their own.^[7]

There are two kinds of sleep study:

• An overnight study in a sleep laboratory (polysomnography). You sleep in a hospital or sleep centre with sensors on your head, chest and finger, and staff watch the recording through the night. It records the widest range of signals.
• A home sleep apnoea test. You wear a smaller device at home, in your own bed, and return it afterwards. For adults with typical symptoms who are otherwise generally well, international guidelines accept home tests that meet set technical standards as a way to diagnose obstructive sleep apnoea.^[7] Those standards were written for devices that record breathing directly. Newer home devices, including some worn as a ring on the finger, use different sensors, such as oxygen level, pulse and movement, and are not covered by that recommendation in the same way. Some are designed to detect moderate to severe sleep apnoea and may miss milder cases. Your doctor will explain what your test can and cannot tell you.

The study gives a count of how many times an hour your breathing stops or becomes shallow. That number is used to say whether sleep apnoea is present, and whether it is mild, moderate or severe. A doctor goes through the result with you, together with your symptoms and your health.

A home test has limits, and it is right that you know them. It can slightly underestimate how severe sleep apnoea is. If the result is negative or unclear but the symptoms are strong, a laboratory study is the next step. A laboratory study is also advised instead of a home test for some people, such as those with significant heart or lung disease, neuromuscular conditions, a previous stroke, long-term use of opioid painkillers, or severe insomnia.^[7]

What it is linked to if left untreated

Repeated drops in oxygen and broken sleep night after night put strain on the heart, blood vessels and metabolism. Large long-term studies have linked untreated sleep apnoea with:

• High blood pressure. The more severe the sleep apnoea, the higher the chance of developing high blood pressure over the following years.^[8] It is especially common in people whose blood pressure stays high despite several medicines.^[9]
• Irregular heartbeat, in particular atrial fibrillation.^[10]
• Heart failure and coronary heart disease, most clearly in men.^[11]
• Stroke.^[12]
• Type 2 diabetes. Moderate to severe sleep apnoea is linked with a higher chance of developing diabetes.^[13]
• Road accidents, because of sleepiness at the wheel.^[14]
• Low mood and depression, and, in a study of older women, problems with memory and thinking.^[15][16]
• A higher risk of dying early in people with severe, untreated sleep apnoea.^[17][18]

These studies show that sleep apnoea and these conditions go together, and that the link grows stronger as sleep apnoea becomes more severe. They do not all prove that sleep apnoea causes each one. Large trials have not shown that CPAP treatment prevents heart attacks or strokes. What treatment does do reliably is improve sleepiness and quality of life, and it lowers blood pressure modestly.^[19][20]

How it is treated

Treatment depends on how severe the sleep apnoea is and how much it affects you. The main options in Singapore's national consensus statements are:^[21]

• CPAP (continuous positive airway pressure): a small machine that blows air gently through a mask while you sleep, keeping the airway open. It is recommended for people with sleep apnoea that causes symptoms, whatever its severity.
• Weight management for people who are overweight.
• An oral appliance, a mouthpiece made by a dentist that holds the lower jaw forward. It is an option for some people with mild to moderate sleep apnoea, or for people who cannot use CPAP.
• Surgery, considered for some people when other treatments have not worked.
• Cutting down on alcohol in the evening, and reviewing sleeping pills with your doctor.^[2]