Effects of Sleep Apnoea: Risks and Treatments

The effects of sleep apnoea extend far beyond feeling tired in the morning. This common condition, in which breathing repeatedly stops and starts during sleep, can affect the heart, blood pressure, metabolism and mental sharpness over time. Obstructive sleep apnoea (OSA) is the most prevalent form, and when left untreated it is associated with serious complications including hypertension, atrial fibrillation and impaired glucose control. Understanding what sleep apnoea does to the body, who is most at risk and what treatments are available on the NHS can help people seek timely diagnosis and protect their long-term health.

What does sleep apnoea actually do to your body?

Sleep apnoea repeatedly deprives the body of oxygen and fragments restorative sleep, causing daytime sleepiness, impaired concentration, disrupted glucose metabolism and elevated inflammatory markers across multiple organ systems.

Sleep apnoea causes repeated interruptions to breathing during sleep, depriving the body of oxygen and fragmenting the restorative sleep it needs to function well. In obstructive sleep apnoea (OSA), the most common form, the muscles at the back of the throat relax excessively, narrowing or completely blocking the airway.^[4][5] Each episode, which can last from a few seconds to over a minute, triggers a brief arousal from sleep as the brain detects falling oxygen levels and signals the body to resume breathing. Partial reductions in airflow, known as hypopnoeas, are counted alongside complete obstructions; together they form the apnoea-hypopnoea index (AHI), which clinicians use to classify severity as mild, moderate or severe.^[2][7]

Over time, these repeated cycles of oxygen deprivation and arousal place considerable strain on multiple organ systems. The immediate effects include daytime sleepiness, poor concentration, irritability and morning headaches, all of which reflect the disrupted sleep architecture rather than simply a short night. People with untreated sleep apnoea often report feeling unrefreshed regardless of how many hours they spend in bed.

Beyond tiredness, the condition has measurable effects on metabolism, immune function and hormonal regulation. Chronic sleep fragmentation is associated with impaired glucose metabolism and changes in appetite-regulating hormones such as leptin and ghrelin, which may contribute to weight gain and make weight management more difficult.^[1][8] The body's inflammatory response is also heightened, with elevated levels of markers such as C-reactive protein observed in people with moderate to severe disease.^[9] These associations are recognised in NICE guidance on obstructive sleep apnoea and hypopnoea syndrome in adults, and they explain why sleep apnoea is now understood as a condition with consequences that extend well beyond the bedroom.

How does untreated sleep apnoea affect your heart and blood pressure?

Untreated sleep apnoea causes repeated overnight blood pressure spikes that lead to sustained hypertension, and is associated with atrial fibrillation, heart failure and coronary artery disease. CPAP therapy can reduce nocturnal blood pressure.

Untreated sleep apnoea is associated with increased risk of high blood pressure, heart disease and stroke, making cardiovascular health one of the most important reasons to seek diagnosis and treatment. Each apnoeic episode triggers a surge in sympathetic nervous system activity, causing the heart rate and blood pressure to spike repeatedly throughout the night.^[10] Over months and years, this nightly pattern of cardiovascular stress is associated with sustained hypertension, even during waking hours.

Research consistently shows that people with moderate to severe obstructive sleep apnoea have a substantially higher prevalence of hypertension compared with the general population.^[11][1] The relationship is partly bidirectional: high blood pressure can worsen sleep apnoea, and sleep apnoea makes blood pressure harder to control, even with antihypertensive medication. NICE guidance on hypertension and on OSA both acknowledge the association, and clinicians are advised to consider sleep apnoea in patients with resistant hypertension.^[12][14]

The cardiac associations extend further. Untreated sleep apnoea is associated with an increased likelihood of atrial fibrillation, heart failure and coronary artery disease.^[10][1] The proposed mechanisms include oxidative stress from intermittent hypoxia, endothelial dysfunction and structural changes to the heart muscle caused by chronic pressure overload. People who have already experienced a cardiac event, particularly atrial fibrillation, and who also have sleep apnoea may face a higher risk of recurrence if the sleep disorder remains unaddressed, though the strength of evidence varies by outcome.

Effective treatment, most commonly continuous positive airway pressure (CPAP) therapy, has been shown to reduce nocturnal blood pressure and improve some markers of cardiovascular risk. Evidence on whether CPAP reduces major adverse cardiovascular events is more mixed, and the degree of benefit depends on consistent use and the severity of the underlying condition.

Who is most at risk of serious complications from sleep apnoea?

People with obesity, men over 50, those with type 2 diabetes or cardiovascular disease, smokers and regular alcohol users face the highest risk of serious complications from sleep apnoea.

People with obesity, particularly those with a body mass index above 30 kg per m², are at substantially higher risk of developing obstructive sleep apnoea and of experiencing its more serious complications. Excess adipose tissue around the neck and upper airway narrows the breathing passage and increases the likelihood of collapse during sleep. However, sleep apnoea also occurs in people of healthy weight, particularly when anatomical factors such as a recessed jaw, enlarged tonsils or nasal obstruction are present.

Several other groups face elevated risk:

• Men are diagnosed with sleep apnoea roughly twice as often as women, though the gap narrows after the menopause, suggesting a hormonal influence.^[17][18]

• People aged over 50 are at greater risk, as muscle tone in the upper airway tends to decrease with age.

• Those with type 2 diabetes have a high prevalence of sleep apnoea, and the two conditions appear to worsen each other's metabolic effects.

• People with cardiovascular disease, including hypertension, atrial fibrillation or a history of stroke, face compounded risk if sleep apnoea is also present.

• Smokers and regular alcohol users are at increased risk, as both substances relax upper airway muscles and worsen airway inflammation.

Pregnancy is another period of heightened vulnerability. Gestational sleep apnoea is associated with pre-eclampsia, gestational diabetes and adverse foetal outcomes, and should be assessed promptly if symptoms arise.^[20][21]

Driving safety is an important consideration. Excessive daytime sleepiness caused by untreated sleep apnoea can significantly impair the ability to drive safely. The DVLA requires drivers to tell them if they have OSA with excessive sleepiness that affects their ability to drive. Anyone who feels they may fall asleep at the wheel must stop driving and seek prompt medical advice. Guidance on notification requirements is available on the DVLA website under "Assessing fitness to drive".

People with any of these risk factors who experience loud snoring, witnessed apnoeas or excessive daytime sleepiness should speak to their GP, who can arrange a referral for a sleep study.

What treatments are available for sleep apnoea on the NHS?

CPAP therapy is the main NHS treatment for moderate to severe OSA; alternatives include mandibular advancement devices, positional therapy, lifestyle changes and, in selected cases, surgery. Referral is made by a GP to a specialist sleep service.

NHS treatment for sleep apnoea depends on the severity of the condition and any contributing factors, with CPAP therapy being the most widely used and evidence-based option for moderate to severe obstructive sleep apnoea. CPAP delivers a continuous stream of pressurised air through a mask worn during sleep, keeping the airway open and preventing apnoeic episodes. When used consistently, it reliably reduces daytime sleepiness, lowers nocturnal blood pressure and improves quality of life. Diagnosis is typically confirmed by a home sleep study (polygraphy) or, where indicated, an in-laboratory polysomnography, with the choice guided by clinical presentation and local service standards.

For people with mild sleep apnoea, or those who cannot tolerate CPAP, alternative options include:

• Mandibular advancement devices (MADs), custom-fitted dental appliances that hold the lower jaw slightly forward to keep the airway open. NICE recommends these as an alternative for people with mild to moderate disease who prefer them or cannot use CPAP.

• Positional therapy, for people whose apnoeas occur predominantly when sleeping on their back.

• Lifestyle modification, including weight loss in people who are overweight or obese (which can meaningfully reduce OSA severity), reducing alcohol intake, stopping smoking and treating nasal congestion.^[25][26] For people with severe obesity, NHS bariatric pathways may also be relevant where clinically appropriate.

• Surgery, in selected cases where a specific anatomical cause such as enlarged tonsils or adenoids is identified, though this is less commonly used in adults.

Referral is typically made by a GP to a specialist sleep service. Commissioning arrangements influence which services and devices are available locally. In England, this is the responsibility of Integrated Care Boards (ICBs); in Scotland, Wales and Northern Ireland, separate NHS commissioning structures apply, so provision can vary across the four nations.^[24] Anyone concerned about symptoms should contact their GP in the first instance rather than waiting, as untreated sleep apnoea carries meaningful long-term health risks.

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