Sleep apnoea

Obstructive sleep apnoea is a condition in which the airway narrows or closes repeatedly during sleep. Each time it does, breathing stops or becomes very shallow for ten seconds or more, blood oxygen falls, and the brain rouses just enough to reopen the airway and start breathing again.

That cycle can repeat dozens or hundreds of times a night, and the person it is happening to generally remembers none of it. What they notice is waking unrefreshed after what should have been a full night, and being exhausted all day without knowing why.

It is common, it is substantially underdiagnosed, and it responds extremely well to treatment. It is also the one sleep condition that carries legal obligations about driving, which are set out below.

Why it matters beyond being tired

Untreated, the repeated drops in oxygen and the repeated rousing put strain on the cardiovascular system. The established associations are with raised blood pressure that is often hard to control, with heart disease and stroke, with atrial fibrillation, and with type 2 diabetes. Sleep apnoea does not simply coexist with those things; treating it improves blood pressure control.

The more immediate risk is accidents. Daytime sleepiness from untreated sleep apnoea measurably raises the chance of a road collision, and that is the reason for the driving rules rather than an abstract caution.

Who gets it

Carrying excess weight is the strongest modifiable factor, particularly weight around the neck and upper body. Beyond that: a larger neck circumference, being male, middle age and older, a family history, smoking, alcohol or sedatives in the evening, nasal obstruction, large tonsils or adenoids, a small or set-back jaw, and the menopause.

One point deserves emphasis because it is the commonest reason the condition is missed. It is substantially under-recognised in women, who more often present with insomnia, fatigue, morning headache and low mood than with the textbook picture of thunderous snoring and a partner describing pauses. A woman reporting exhaustion and poor sleep is more likely to be assessed for depression or an underactive thyroid than for sleep apnoea, and the condition is frequently found years late.

It also occurs in people who are not overweight, and in children, where enlarged tonsils are the usual cause.

What it looks like

At night: loud snoring, often with pauses followed by a gasp, snort or choke. Restless sleep, sweating, waking suddenly, needing to pass urine more than once.

By day: waking unrefreshed, a dry mouth or sore throat on waking, morning headache, and sleepiness that is not ordinary tiredness — falling asleep while reading, watching television, in a meeting, or at traffic lights. Alongside that, poor concentration and memory, irritability, low mood and reduced libido.

Snoring on its own is not sleep apnoea, and plenty of people with sleep apnoea do not snore dramatically. The combination that should prompt assessment is unrefreshing sleep plus daytime sleepiness, especially with witnessed pauses in breathing.

What a partner can and cannot do

A bed partner usually notices first, and what they observe is genuinely valuable — the pauses, the gasping, how often, whether it is worse lying on the back, whether it has worsened over time. Taking those observations to an appointment makes the consultation much more useful, and a phone recording of the breathing can be convincing.

What that is not is a diagnosis. Older advice suggests a partner can establish the condition with a notepad and a count of interruptions, and the distinction matters because counting events at home is exactly what leads people to conclude they have a mild version of something and need do nothing further. Severity is measured by a test, and the number that matters cannot be arrived at by observation.

How it is actually diagnosed

A GP assessment usually starts with the Epworth Sleepiness Scale, a short questionnaire scoring how likely a person is to doze in various everyday situations. It measures sleepiness rather than sleep apnoea, and a high score is a reason to investigate.

Diagnosis is then made by a sleep study, and in the UK this is usually done at home rather than in a hospital. Overnight oximetry records oxygen levels through a finger probe; respiratory polygraphy adds airflow, breathing effort and sometimes position and sound. Full in-laboratory polysomnography exists and is reserved for complicated cases.

The result is expressed as an apnoea-hypopnoea index — the average number of breathing events per hour of sleep — which places the condition as mild, moderate or severe and determines what is offered.

Three things that are not how it is diagnosed, and which older writing suggests: nasal endoscopy, an X-ray, and a CT scan of the head and neck. Those have a place in looking at anatomy before surgery. They do not establish sleep apnoea, because the condition is defined by what happens to breathing during sleep.

Treatment

Continuous positive airway pressure is the main treatment and the effective one. A small bedside unit delivers a gentle stream of pressurised air through a mask, which holds the airway open mechanically. UK guidance recommends it for moderate and severe disease, and also for mild disease where symptoms are affecting daytime life.

It is not a cure — the apnoea returns on any night it is not used — and the honest difficulty with it is tolerance. Masks leak, air feels cold or drying, and a proportion of people give up in the first weeks. That is a solvable problem rather than a verdict: mask type, humidification and pressure settings can all be adjusted, and sleep services expect to do exactly that. People who persist through the first fortnight frequently describe the effect on their daytime life as the most dramatic improvement they have had from any treatment.

A mandibular advancement splint is the main alternative, recommended at any severity for people who decline CPAP or cannot tolerate it. It holds the lower jaw slightly forward overnight. The important detail is that an effective one is custom-made or semi-custom, fitted by a dentist — the boil-and-bite mouthguards sold for snoring are not the same device and are not what the guidance refers to.

Weight, where excess weight is part of the picture, is genuinely effective: a relatively modest reduction can lower the index substantially, and in mild cases can resolve it. Newer weight-loss treatments have changed what is achievable here. This is support for treatment rather than a replacement for it, and in moderate or severe disease nobody should be waiting on weight loss before starting CPAP.

Also useful: avoiding alcohol and sedatives in the evening, since both relax the airway; stopping smoking; treating nasal obstruction; and, for people whose apnoea occurs mainly on their back, measures to stay off it. Surgery has a role in selected cases, principally children with large tonsils, and is not a routine adult treatment.

One correction to the older advice on this subject. It stated that someone diagnosed with sleep apnoea "can self-treat", with weight loss as the most effective method. The lifestyle measures above all help. They are not an alternative to CPAP in moderate or severe disease, and treating them as one is a large part of why people stay untreated for years.

Driving, and what the law requires

This section is the reason the article exists, and it is absent from almost all older writing on the subject.

Nobody should drive while excessively sleepy. Under UK rules, driving must stop until the sleepiness has gone, or until symptoms are under control and any necessary treatment is being followed properly.

The DVLA must be told in these circumstances:

• Confirmed moderate or severe obstructive sleep apnoea syndrome with excessive sleepiness.
• Narcolepsy or cataplexy, or both.
• Any other sleep condition that has caused excessive sleepiness for three months or more — which includes suspected as well as confirmed mild sleep apnoea syndrome.

The route differs by licence. A car or motorcycle licence is reported online or on form SL1. A bus, coach or lorry licence uses form SL1V.

Not declaring a condition that affects driving carries a fine of up to £1,000, and prosecution is possible where someone is involved in an accident as a result.

Two things worth saying alongside that, because fear of losing a licence is a real reason people avoid being assessed. Telling the DVLA is not the same as losing the licence — most people with treated sleep apnoea continue to drive, and the declaration is part of a process rather than the end of one. And the risk being managed is not hypothetical: falling asleep at the wheel is the outcome the rules exist to prevent, and it happens.

When to ask for an assessment

• Snoring with witnessed pauses, gasping or choking.
• Waking unrefreshed most mornings, with sleepiness during the day that is not explained by short nights.
• Falling asleep when inactive — reading, watching something, as a passenger, or worst of all while driving or operating machinery.
• High blood pressure that is difficult to control, which is a recognised reason to look for sleep apnoea.
• Exhaustion and poor sleep in a woman that has been attributed to something else and has not improved with that something else being treated.
• A child who snores heavily with pauses, is restless at night, breathes through the mouth, or is unusually tired or badly behaved by day.

And immediately, rather than at the next convenient appointment, for anyone who has felt themselves becoming drowsy at the wheel.