Sleep Apnoea and the Gastric Sleeve: CPAP Before Surgery, and Whether It Goes Away

Obstructive sleep apnoea is a condition where the airway narrows during sleep so that breathing repeatedly stops and starts, and it is common enough in people heading for a gastric sleeve that most bariatric teams screen for it before they will book a date; if you have it, CPAP usually comes first, and whether you can give the machine up later is decided by a repeat sleep study, not by how rested you feel. It is one of the least talked about parts of the pre-op process, and one of the most useful.

I scored low on the screening questionnaire before my own surgery and thought no more about it. Then I sat in a support group a few months later and listened to three different people describe the same story: a referral they did not expect, an overnight study they resented, a mask they hated for a fortnight, and then the strange discovery that they had not slept properly in years. This is what I wish I had been able to give them beforehand.

What sleep apnoea is, and why it matters before a sleeve

Sleep apnoea happens when the airway becomes too narrow while you sleep, so breathing stops and starts through the night, often with loud snoring, gasping or choking sounds, and broken sleep that leaves you tired the next day. The NHS lists obesity, a large neck, older age, alcohol, smoking and sleeping on your back among the things that make it more likely¹.

Excess weight matters because fat around the neck and upper airway narrows the space air has to pass through, and fat around the abdomen reduces lung volume, so the airway collapses more easily when the muscles relax in sleep. That is why sleep apnoea and the conditions that qualify people for surgery so often travel together. UK guidance on weight loss surgery treats obesity related conditions, including breathing problems, as part of the case for an operation²³.

The reason a surgical team cares so much is the anaesthetic. A general anaesthetic, and the strong pain relief used afterwards, both relax the muscles that hold the airway open. In someone with untreated sleep apnoea, that makes the airway harder to manage during the operation and more likely to collapse in the first nights on the ward. Knowing beforehand lets the anaesthetist plan for it and lets you arrive already treated.

How the screening and sleep study work

Screening usually starts with a handful of questions at your pre-op assessment about snoring, whether anyone has seen you stop breathing, daytime sleepiness, blood pressure and neck size, and anyone who scores high is referred for an overnight sleep study. Many units use a short standardised questionnaire for this; the questions are simple, and the honest answer is the useful one.

The study itself is far less of an ordeal than people expect. You wear small devices overnight that record your breathing, oxygen levels and heartbeat, and the NHS notes that you can usually do this at home, though sometimes you may need to stay in a clinic overnight¹. A sensor on the finger, a band around the chest, and a soft tube under the nose is the usual kit.

The result is given as an apnoea hypopnoea index, or AHI, which is the average number of times an hour your breathing stops or becomes very shallow. The NHS grades it like this¹:

• AHI 5 to 14: mild sleep apnoea
• AHI 15 to 30: moderate sleep apnoea
• AHI over 30: severe sleep apnoea

A mild result may not change much about your surgery plan. A moderate or severe one almost always means treatment before the operation.

CPAP before surgery, and the delay it can cause

If the sleep study is positive, most bariatric teams want you on CPAP for a period before surgery, which can push the date back while you get used to it. CPAP stands for continuous positive airway pressure: a small machine by the bed gently pumps air through a mask, which holds the airway open while you sleep. The NHS notes it is free on the NHS if you need it¹.

Nobody I have spoken to liked it at first. The mask feels claustrophobic, the air feels odd, and the first week of nights can be worse rather than better. The tips that come up again and again are dull and effective: try more than one mask style, wear it for short spells while awake reading or watching television, use the humidifier if the air dries your mouth, and ring the sleep clinic about leaks rather than giving up. Many people say the turning point arrives within the first few weeks, often marked by noticing that the afternoon slump has gone.

How long you need to be on it before surgery is your team’s call. It depends on the severity and on unit policy, and the preparing for surgery guide covers how it fits around the liver shrink diet and the other pre-op steps. A delay is frustrating when you have waited a long time already. It is also one of the more sensible delays in the whole process.

Using CPAP in hospital and the first weeks at home

Most hospitals ask you to bring your CPAP machine, mask and tubing on the day and to use it from the first night after surgery, because that is when the airway is most vulnerable. The effects of the anaesthetic, the pain relief, and lying in a hospital bed all work against you, and the machine is the simplest protection there is. Label everything, pack it in the main bag, and make sure the nurses know you use it.

At home the same logic applies for the first weeks while you are still taking stronger painkillers. The day of surgery guide covers what the ward routine looks like; CPAP just becomes part of the bedtime routine alongside sips of water and getting up to walk.

Two practical points catch people out. A new sleeve means you are sipping small amounts all day, so a dry mouth from the mask can feel worse than before; the humidifier setting helps. And because the face changes quickly as weight falls, a mask that fitted in month one may leak by month four. Leaks are a reason to ask for a refit, not a sign the treatment has stopped working.

Does sleep apnoea go away after a gastric sleeve?

For many people sleep apnoea improves a great deal as the weight comes off, and some no longer need CPAP after a substantial loss, but it does not resolve for everyone, and only a repeat sleep study can tell you which group you are in. Weight is a major driver of the condition, and losing it reduces the narrowing around the airway, which is why the NHS lists losing weight among the first things that help¹.

Weight is not the only driver, though. Jaw shape, the structure of the neck and throat, older age, alcohol and smoking all play a part, so someone can lose a great deal of weight and still have apnoea. The pattern I have seen most often is improvement over the first year, a repeat study somewhere along the way, and either a lower pressure setting or the machine going back. Your expected weight loss gives a rough sense of the timeline, but the study is the decision point.

The commonest mistake is stopping because you feel better. Feeling less tired is partly the CPAP working and partly better sleep overall; it does not prove the apnoea has gone. Untreated sleep apnoea is linked to high blood pressure and other long-term problems, so the sensible route is to keep using the machine until your sleep service has retested you and said you can stop. If you think you no longer need it, that is the conversation to ask for.

Alcohol deserves a mention because it relaxes the airway muscles and makes apnoea worse. After a sleeve it also hits much harder than before, which the alcohol guide covers, so the two reasons to be careful with it stack together.

Driving, work, and the DVLA

The NHS advises that you may need to tell the DVLA if you have sleep apnoea, and that if excessive sleepiness has been confirmed you must not drive until symptoms like feeling very tired are under control. The full rules sit on GOV.UK and depend on how severe the condition is and whether it affects your driving¹.

In practice, most people who are diagnosed and using CPAP well find the sleepiness lifts, and that is what the rules are concerned with. If you drive for a living, ask your sleep clinic early what applies to you, because professional licences have their own requirements. Being diagnosed is not the problem; driving while sleepy and untreated is.

What I would tell anyone who has just been referred

A sleep study referral before a sleeve is not an obstacle put in your way; it is one of the few parts of the process that can make the operation safer and your life better at the same time. Answer the screening questions honestly, do the study, give CPAP a proper three weeks before deciding you hate it, take it into hospital, and keep using it until someone with a repeat study tells you otherwise⁴.

If you are still deciding whether surgery is right for you, sleep apnoea is one of the conditions that can count towards eligibility, which the candidacy guide explains.

This guide is general information and one person’s experience, not medical advice. Whether you need a sleep study, how long to use CPAP before surgery, and when it is safe to stop are decisions for your bariatric team and your sleep service, who know your results.